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WO2025237702A1 - Appareil et procédé d'insertion de dispositif intracrânien et de fixation de crâne - Google Patents

Appareil et procédé d'insertion de dispositif intracrânien et de fixation de crâne

Info

Publication number
WO2025237702A1
WO2025237702A1 PCT/EP2025/062104 EP2025062104W WO2025237702A1 WO 2025237702 A1 WO2025237702 A1 WO 2025237702A1 EP 2025062104 W EP2025062104 W EP 2025062104W WO 2025237702 A1 WO2025237702 A1 WO 2025237702A1
Authority
WO
WIPO (PCT)
Prior art keywords
guide
tool
instrument
datum
stop
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/EP2025/062104
Other languages
English (en)
Inventor
Steven Streatfield Gill
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Neurochase Technologies Ltd
Original Assignee
Neurochase Technologies Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Neurochase Technologies Ltd filed Critical Neurochase Technologies Ltd
Publication of WO2025237702A1 publication Critical patent/WO2025237702A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
    • A61B90/10—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges for stereotaxic surgery, e.g. frame-based stereotaxis
    • A61B90/11—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges for stereotaxic surgery, e.g. frame-based stereotaxis with guides for needles or instruments, e.g. arcuate slides or ball joints
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B17/34—Trocars; Puncturing needles
    • A61B17/3468—Trocars; Puncturing needles for implanting or removing devices, e.g. prostheses, implants, seeds, wires
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B17/16—Instruments for performing osteoclasis; Drills or chisels for bones; Trepans
    • A61B17/1655—Instruments for performing osteoclasis; Drills or chisels for bones; Trepans for tapping
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B17/16—Instruments for performing osteoclasis; Drills or chisels for bones; Trepans
    • A61B17/1695—Trepans or craniotomes, i.e. specially adapted for drilling thin bones such as the skull
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B17/16—Instruments for performing osteoclasis; Drills or chisels for bones; Trepans
    • A61B17/17—Guides or aligning means for drills, mills, pins or wires
    • A61B17/1739—Guides or aligning means for drills, mills, pins or wires specially adapted for particular parts of the body
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B2017/00477—Coupling
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods
    • A61B17/34—Trocars; Puncturing needles
    • A61B17/3417—Details of tips or shafts, e.g. grooves, expandable, bendable; Multiple coaxial sliding cannulas, e.g. for dilating
    • A61B2017/3454—Details of tips
    • A61B2017/3458—Details of tips threaded
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B34/00—Computer-aided surgery; Manipulators or robots specially adapted for use in surgery
    • A61B34/20—Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
    • A61B2034/2046—Tracking techniques
    • A61B2034/2055—Optical tracking systems
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B34/00—Computer-aided surgery; Manipulators or robots specially adapted for use in surgery
    • A61B34/20—Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
    • A61B2034/2072—Reference field transducer attached to an instrument or patient
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
    • A61B90/03—Automatic limiting or abutting means, e.g. for safety
    • A61B2090/033—Abutting means, stops, e.g. abutting on tissue or skin
    • A61B2090/034—Abutting means, stops, e.g. abutting on tissue or skin abutting on parts of the device itself
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
    • A61B90/03—Automatic limiting or abutting means, e.g. for safety
    • A61B2090/033—Abutting means, stops, e.g. abutting on tissue or skin
    • A61B2090/036—Abutting means, stops, e.g. abutting on tissue or skin abutting on tissue or skin
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
    • A61B90/06—Measuring instruments not otherwise provided for
    • A61B2090/062—Measuring instruments not otherwise provided for penetration depth
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
    • A61B90/08—Accessories or related features not otherwise provided for
    • A61B2090/0807—Indication means
    • A61B2090/0811—Indication means for the position of a particular part of an instrument with respect to the rest of the instrument, e.g. position of the anvil of a stapling instrument
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
    • A61B90/10—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges for stereotaxic surgery, e.g. frame-based stereotaxis
    • A61B2090/103—Cranial plugs for access to brain
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B34/00—Computer-aided surgery; Manipulators or robots specially adapted for use in surgery
    • A61B34/30—Surgical robots
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
    • A61B90/10—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges for stereotaxic surgery, e.g. frame-based stereotaxis
    • A61B90/14—Fixators for body parts, e.g. skull clamps; Constructional details of fixators, e.g. pins
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/02—Details
    • A61N1/04—Electrodes
    • A61N1/05—Electrodes for implantation or insertion into the body, e.g. heart electrode
    • A61N1/0526—Head electrodes
    • A61N1/0529—Electrodes for brain stimulation
    • A61N1/0539—Anchoring of brain electrode systems, e.g. within burr hole

Definitions

  • the present invention relates to systems and methods for use in neurosurgery. More particularly, the invention relates to a system for forming a profiled hole in the skull for the insertion and fixation of medical devices for use in neurotherapeutics and neurodiagnostics.
  • Medical devices with skull fixation are used to treat or monitor a broad range of neurological diseases. Examples include the implantation of Deep Brain Stimulating (DBS) and recording leads for the treatment of movement disorders, neuropsychiatric disorders, chronic pain and epilepsy; insertion of Stereoelectroencephalography (SEEG) leads for the localisation of an epileptic focus; implantation of catheters into ventricles or cysts for the drainage of fluid; the insertion or implantation of intraparenchymal cannulas for drug delivery to the brain for the treatment of neurodegenerative diseases and brain tumours; insertion of an intracranial pressure sensor to monitor brain injury; insertion of a laser ablation or stimulation probe, implantation of brachytherapy devices, implantation of a cochlear implant, and implantation of a bone anchored port for the delivery or withdrawal of fluid or connection to an electrical recording or stimulation device (brain-computer interface).
  • DBS Deep Brain Stimulating
  • SEEG Stereoelectroencephalography
  • Insertion or implantation of devices to targets in the brain requires a high level of accuracy, preferably sub millimetre, to avoid damage to eloquent neural structures and vessels along the trajectory, to minimise off target side-effects, and to maximise therapeutic benefit.
  • This level of accuracy can be achieved with radiological image-guided stereotactic procedures.
  • targets within the brain and trajectories to them are identified on radiological images and their image-based 3D coordinates are co-registered with the 3D coordinate system of a surgical targeting instrument or stereotactic instrument This registration is conventionally achieved with reference to fiducials, visible on radiological images that are attached to a base frame fixed to the patient’s head.
  • the derived target and trajectory coordinates are set in the stereotactic instrument which is then kinematically fixed to the base frame and instruments guided to the target.
  • so-called frameless registration can be achieved by mechanical means using an arm with position sensors or optically or electromagnetically tracked instruments to locate the position of radio-opaque markers that were fixed to the patient’s head during image acquisition or to trace the patient’s facial profile with their head fixed to an operating table.
  • Stereotactic instruments in this broader context in which an instrument guide can be fixed in alignment with the image derived coordinates of a target trajectory may include an instrument guide on a moveable and lockable multi-joint arm and a surgical robot
  • Targets in the brain can include anatomical structures or pathological structures such as tumours.
  • the limitations of current methods for stereotactically delivering and securing long term implantable devices to the skull, such as electrode leads and catheters, may include one or more of: 1) a complex workflow that adds to procedure time, anaesthetic risk and the risk of human error, 2) requirement for a large burr hole for device implantation which increases the wound size, the risk of bleeding and the risk of perioperative pneumocephalus with brain shift, 3) excessive device handling with increased risk of infection, 4) movement of the device from the target when it is being secured, 5) inadequate fixation of the device resulting in its intracranial migration, 6) failure to seal around the implant as it passes through a hole in the skull which leaves a conduit for cerebrospinal fluid (CSF) to leak out or bacteria to enter the cranial cavity, 7) excessive protuberance of the device above the skull surface increasing the risk of scalp erosion and/or being cosmetically unacceptable, 8) inability to replace the device without repeating a full stereotactic procedure.
  • CSF cerebrospinal fluid
  • the stereotactic insertion of DBS electrodes to brain targets and securing them to the skull using image-guided stereotactic neurosurgery typically involves the following:
  • the patient’s head is fixed relative to a stereotactic instrument and its instrument guide is aligned with the trajectory to an intracranial target that has been defined from radiological images.
  • a skull entry point is identified along the trajectory, and a burr hole made at the entry site through a scalp incision after moving the stereotactic instrument away from the operative field.
  • the burr hole is frequently made with a 14mm diameter skull perforator which will accommodate commercially available DBS lead fixation devices such as the Stim lockTM Burr Hole Cover (Medtronic Inc.), the Sure TekTM Burr Hole Cover (Boston Scientific) or the GuardianTM Burr Hole Cover (Abbott/ St Jude Medical)
  • DBS lead fixation devices such as the Stim lockTM Burr Hole Cover (Medtronic Inc.), the Sure TekTM Burr Hole Cover (Boston Scientific) or the GuardianTM Burr Hole Cover (Abbott/ St Jude Medical)
  • burr hole covers comprise three components: a base ring that is fixed around the burr hole with screws; a lead retaining clip which is positioned in the ring and around the implanted DBS lead; and a cap that snap-fits into the ring and compresses the lead onto features on the retaining clip, after the lead is bent 90°over the clip.
  • a base ring that is fixed around the burr hole with screws
  • a lead retaining clip which is positioned in the ring and around the implanted DBS lead
  • a cap that snap-fits into the ring and compresses the lead onto features on the retaining clip, after the lead is bent 90°over the clip.
  • Burr Hole Covers proves effective in minimising lead migration their design and method of insertion are otherwise subject to all the aforementioned limitations.
  • PCT/GB2022/051104 publication number WO2022/229662A1
  • PCT/GB2022/051104 publication number WO2022/229662A1
  • PCT/GB2022/051104 publication number WO2022/229662A1
  • WO2022/229662A1 teaches the use of a Guide Hub inserted in a profiled hole made through the skull made along a trajectory to a brain target.
  • the Guide Hub comprises a through-bore for delivering a device therethrough and along the trajectory; at least one first formation on an external surface for securing the hub within the aperture in a skull; and at least one second formation on the surface of the through-bore for securing a guide device, an implantable device, or a cap to the hub.
  • the Guide Hub is compact and low profile and fixes devices at the level of the skull surface, which greatly reduces the risk of mechanical dislodgement and enables the scalp to be closed over the hub with a low risk of skin erosion
  • the inserted Guide Hub provides a datum surface at skull surface level, which in combination with a bore, sized to be a close fit and coaxial with the trajectory of the device to be implanted, augments the accuracy of device insertion and fixation. These features also facilitate the redelivery of devices to brain targets without the need for more extensive stereotactic targeting procedures. This may be useful when replacing obstructed catheters, faulty DBS electrodes, or repeated dosing of gene therapies, chemotherapeutics or repeating lesioning procedures.
  • a further advantage described is the robust mechanical fixation of devices that the Guide Hub affords in addition to providing a fluid seal around the implanted devices to prevent the leakage of CSF and impede the intracranial ingress of bacteria
  • the Guide Hub may also be used advantageously for the fixation of stereotactically inserted devices into the brain for short term neurodiagnostic or therapeutic purposes. It is often desirable to insert several SEEG electrodes or cannulas for drug delivery in the operating theatre and then monitor the patient awake on the ward over a day or more during the investigation or treatment before removing the electrodes or cannulas.
  • the low-profile fixation of the flexible electrode leads or cannulas enables the scalp to be closed over their insertion site and for them tunnelled subcutaneously. This reduces the likelihood of their inadvertent mechanical displacement and the risk of infection
  • the cutting tools described in PCT/GB2022/051104 are 1) a Facing Tool to make a flat on the curved skull surface to reduce the likelihood of a pilot drill skiving, 2) a Pilot Drill to form a hole through the skull along the chosen trajectory, 3) a Core Drill to make a profiled hole in the skull to accept the Guide Hub, and 4) a Guide Hub Delivery Tool to insert the Hub, which may have a self-tapping thread, into the profiled hole.
  • each cutting tool is required to cut the skull to a predetermined depth from the skull surface and from the stereotactic instrument guide datum
  • all the tool lengths are advantageously set in a jig.
  • the jig aligns the tools in a rectangular frame with vertical channels in an upper crossbeam whose top surface represents the stereotactic instrument guide datum (the Representative Datum).
  • a lower crossbeam (the Reference Guide), moveable with respect to the Representative Datum, has a datum surface that is representative of the skull surface
  • the prescribed depth of insertion of each tool below the skull surface is represented in the jig by an offset in the surface of the Reference Guide
  • a Datum Tool In use, when the stereotactic instrument's guide is aligned with the brain target, a Datum Tool, a cylindrical rod with a distal conical tip, is inserted through the stereotactic instrument guide and brought into contact with the skull surface. A collar clamp on the Datum Tool is used to lock-off the distance from the Instrument Guide’s datum surface to the skull surface. The Datum Tool is then transferred to the Jig where the collar clamp is located on the Representative Datum and the datum surface on the Reference Guide is moved to contact the tip of the Tool and its position is fixed. When moving the Reference Guide all the tools located in its offsets are moved with it. Collar-clamps on each of the tools are locked, which precisely sets the tools without the need for individual setting against measurement scales.
  • the depth of insertion of the pilot drill is manually set to ensure that it will penetrate through the inner table of the skull, a distance derived from surgical planning images.
  • the pre-set tools for forming a profiled hole in the skull and inserting the Guide Hub are now removed sequentially from the Jig and deployed via the Stereotactic Instrument Guide.
  • the distance from the Stereotactic Instrument Datum to the target is known.
  • the jig described in PCT/GB2022/051104 may also have a third cross beam representing the target.
  • the Target Datum is positioned at the known Stereotactic Instrument Datum to target distance from the Representative Datum, and the moveable Reference Guide is positioned between them.
  • the Reference Guide to Target Datum distance is also established and fixed. This equals the skull surface to target distance.
  • the datum surface of the Reference Guide has features to receive the proximal end of the device to be inserted that will be fixed in the Guide Hub and the tools required to insert it.
  • the depth of the device or tool to be inserted is set by advancing its distal end to the Target Datum and locking off the length, or in some cases cutting the device to the required length using a cutting jig set in the Target Datum crossbeam.
  • the device delivery tools may now be used to insert the device to the brain target via the Guide Tube in which the device is then secured.
  • a system for use in stereotactic neurosurgery comprising a guide and a reference tool, wherein: the guide is configured to receive a surgical tool for use in stereotactic surgery; the guide comprises an instrument guide stop configured to engage with a datum surface of a stereotactic instrument; a position of the instrument guide stop on the guide is adjustable; a distal end of the reference tool is configured to engage with a skull; and the guide is configured to rigidly engage with the reference tool such that a distance between a proximal end of the guide and the distal end of the reference tool is equal to a predetermined reference length.
  • the use of the guide and reference tool with the adjustable instrument guide stop allows the guide to be set into the stereotactic instrument such that the proximal end of the guide always adopts a known position relative to the skull surface. This can be achieved regardless of the configuration of the stereotactic instrument.
  • tools can be standardised for use with the guide without having to adjust each tool individually based on the configuration of the stereotactic instrument, as is necessary with the system disclosed in PCT/GB2022/051104
  • the guide is configured to engage with the stereotactic instrument such that the surgical tool is aligned along a trajectory to a surgical target when it is received in the guide
  • the guide can also be used with tools for implanting devices into the brain, not only with tools for processing the skull surface
  • the instrument guide stop comprises a collar clamp This is a convenient type of adjustable clamp that is readily available and adaptable to the guide
  • the instrument guide stop comprises a proximal portion and a distal portion, the distal portion having a diameter less than a diameter of the proximal portion. This allows the guide stop to engage more securely with the stereotactic instrument by having a distal portion that inserts into the appropriate part of the stereotactic instrument.
  • the proximal portion is configured to engage with the datum surface of the stereotactic instrument. This provides an accurate correspondence of the position of the proximal end of the guide relative to the stereotactic instrument.
  • the guide is a tool guide and the reference tool is a datum tool
  • engagement of the distal end of the datum tool with the skull comprises contacting a surface of the skull with the distal end of the datum tool.
  • the engagement of the datum tool with the tool guide comprises one or both of: a) engagement of a proximal stop of the datum tool with a proximal end of the tool guide; and b) engagement of corresponding fastening mechanisms on the tool guide and the datum tool, optionally wherein the fastening mechanisms comprise screw threads or bayonet fittings. Fastening mechanisms in particular can prevent the datum tool moving relative to the tool guide during the positioning and securing of the instrument guide stop.
  • the tool guide is configured to receive the surgical tool and/or the datum tool in a throughbore of the tool guide. This provides a secure and reproducible method for positioning the datum tool and surgical tool relative to the tool guide.
  • the datum tool comprises one or more tracking fiducials for tracking of the position of the datum tool, optionally wherein the fiducials comprise a plurality of optical tracking fiducials. This allows for registration of the datum tool and tool guide on guidance imaging during surgery
  • the tool guide has a length shorter than the predetermined reference length, optionally at least 2 cm shorter, optionally at least 5 cm shorter. This provides a working space between the distal end of the tool guide and the skull surface, for example for removal of debris when drilling.
  • a length of the tool guide is between 100mm and 200mm, optionally approximately 150mm. These dimensions are convenient for ease of handling and compatibility with typical stereotactic instruments and surgical tools
  • the tool guide further comprises a target depth stop located proximally of the instrument guide stop, optionally wherein the target depth stop comprises a collar clamp.
  • a target depth stop located proximally of the instrument guide stop, optionally wherein the target depth stop comprises a collar clamp.
  • a distance between a surface of the target depth stop and the distal end of the datum tool when the datum tool is engaged with the tool guide is equal to a distance between the datum surface of the stereotactic instrument and the surgical target.
  • this can be used for setting the length of an implantable device intended to reach the target from the skull surface.
  • a position of the target depth stop on the tool guide is adjustable This allows the tool guide to be adjusted for use with different stereotactic instruments that have different distances between the datum surface and the surgical target
  • the system in which the guide is a tool guide and the reference tool is a datum tool may be provided as part of a kit for use in stereotactic neurosurgery further comprising a bone machining tool, wherein the bone machining tool comprises a proximal stop configured to engage with the proximal end of the tool guide; a distance between the proximal stop of the bone machining tool and a distal end of the bone machining tool is greater than the reference length by a machining distance by which the bone machining tool is intended to penetrate the skull surface during the stereotactic neurosurgery This allows the bone machining tool to be inserted to the correct depth by straightforwardly engaging it with the tool guide, without having to adjust the bone machining tool itself.
  • the engagement of the alignment instrument with the device guide comprises engagement of a proximal clamp of the device guide with a proximal region of the alignment instrument This allows the relative position of the device guide and alignment instrument to be fixed to prevent relative movement while setting up the device guide.
  • the device guide is configured to receive the surgical tool and/or the alignment instrument in a throughbore of the device guide. This provides a secure and reproducible method for positioning the alignment instrument and surgical tool relative to the device guide.
  • the system further comprises a conical guide configured to removably engage with a distal end of the device guide, the conical guide reducing the diameter of a distal end of the throughbore to at most 2mm, optionally at most 1 mm, optionally at most 0 5mm This allows for more precise guidance of narrow surgical tools or devices such as DBS leads when implanting them into the brain.
  • a distal region of the device guide comprises an aperture providing access to the throughbore of the device guide. This allows access close to the skull surface, which may be useful when the device to be implanted has a larger diameter portion such as a connector or filter that would not fit through the throughbore of the device guide.
  • the distal end of the alignment instrument comprises a bayonet fitting for engagement with the guide hub This ensures secure engagement while also fixing the rotational alignment of the device guide and guide hub.
  • the system in which the guide is a device guide and the reference tool is an alignment instrument may be provided as part of a kit for use in stereotactic neurosurgery further comprising a surgical tool, wherein the surgical tool comprises a proximal stop configured to engage with the proximal end of the device guide; the surgical tool further comprises one or more alignment features configured to engage with the alignment feature of the device guide such that the surgical tool and the device guide adopt a predetermined relative rotational alignment when the surgical tool is engaged with the device guide.
  • This allows the surgical tool to be inserted to the correct depth with an appropriate alignment by straightforwardly engaging it with the device guide, without having to adjust the surgical tool itself.
  • a tool guide for use in stereotactic neurosurgery comprising: a throughbore configured to receive a surgical tool or a datum tool for use in stereotactic surgery; and an instrument guide stop configured to engage with a datum surface of a stereotactic instrument, wherein one or both of: a) the tool guide further comprises a target depth stop located proximally of the instrument guide stop; and b) the proximal end of the tool guide further comprises a fastening mechanism for engagement with a corresponding fastening mechanism on the surgical tool or datum tool.
  • This tool guide allows for convenient alignment of surgical tools by using the known position of the target depth stop, or for secure engagement with the datum tool for more reliable setup of the tool guide.
  • a method of using the system of the first aspect of the invention comprising: inserting the guide rigidly engaged with the reference tool into an instrument guide of the stereotactic instrument until the distal end of the reference tool engages a skull; adjusting the position of the instrument guide stop such that the instrument guide stop engages with the datum surface of the stereotactic instrument
  • the method further comprises disengaging the reference tool from the guide; and inserting the surgical tool into the guide. This provides the guide adjusted ready to receive a tool for operation without requiring specific setup of the tool.
  • FIGURES Fig 10 shows the tools of Fig 9A to Fig. 9E in a cranial preparation tool holder
  • Fig 11 A and Fig. 11 B show a guide hub and guide hub locking cap
  • Fig 12 shows an embodiment of a device preparation jig for use in delivering a DBS lead
  • Fig 13A to Fig. 13C show device delivery tools for use in delivering a DBS lead
  • Fig 14A to Fig. 14C show a cannula assembly
  • Fig 15 shows an embodiment of a device preparation jig for use in delivering a cannula assembly
  • Fig 16A to Fig. 16D show a guide tube track forming instrument
  • Fig 17A and Fig 17B show a cannula delivery instrument
  • Fig 18 shows a cutting tool
  • Fig 19A and Fig. 19B show the use of the cutting tool of Fig. 18 for cutting a guide tube
  • Fig 20A and Fig. 20B show the use of the cutting tool of Fig. 18 for cutting the guide tube in situ in the device preparation jig;
  • Fig 21 shows the device preparation jig of Fig. 15 during the setting of the insertion depth of a probe of the guide tube delivery instrument
  • Fig 22A and Fig. 22B show the use of the cutting tool of Fig. 18 for cutting the cannula in situ in the device preparation jig;
  • Fig 23A and Fig. 23B show the priming of the cannula in the device preparation jig
  • Fig 24 shows the cannula delivery instrument with attached conical guide ready for delivery of the cannula
  • Fig 25 shows the cannula delivery instrument of Fig. 24 at a later stage of delivery of the cannula
  • Fig 26A to Fig. 26D shows the engagement of the cannula with the guide hub and subsequent disengagement of the cannula delivery instrument from the guide hub and cannula;
  • Fig 27 shows the delivered cannula in situ on the skull.
  • the present invention relates to systems and methods for use in stereotactic neurosurgery. More particularly, the invention relates to a system for forming a profiled hole in the skull for the insertion and fixation of medical devices for use in neurotherapeutics and neurodiagnostics. Also disclosed is a jig for setting the depth of insertion of neurosurgical tools or devices into a patient during surgery. The system and jig are particularly useful in image-guided stereotactic neurosurgery where accurate and reproducible targeting is required.
  • the system for use in stereotactic neurosurgery comprises a guide and a reference tool.
  • the guide and reference tool may take different forms depending on the specific aspect of the surgery in which they are designed to assist Fig. 1 and Fig. 2 show a specific example in which the guide is a tool guide 1 and the reference tool is a datum tool 3. This and other examples will be discussed in more detail below.
  • the purpose of the guide and reference tool is to provide a well-defined, standardised reference point relative to a skull surface or a surgical target from which surgical tools and devices can be deployed.
  • surgical tools can be standardised and reduces the number of operations required to set individual surgical tools and devices compared to current systems.
  • the system also allows some setting operations to be performed by simple mechanical engagement of parts, rather than by manual manipulation, for example, against measuring scales. This reduces the time and complexity for performing neurosurgical procedures and reduces the chance of human error.
  • the guide is configured to receive a surgical tool for use in stereotactic surgery.
  • the surgical tool may be any tool typically used in neurosurgery Specific examples of surgical tools will be discussed in detail below, but can include bone machining tools for drilling holes in a patient’s skull, probes for creating tracks in the brain, delivery tools for inserting cannulas or DBS leads into the brain, and so forth
  • the guide comprises an instrument guide stop 5 configured to engage with a datum surface of a stereotactic instrument.
  • the datum surface may be provided by an instrument guide 7 of the stereotactic instrument, as shown in Fig. 1 .
  • the stereotactic instrument may be any suitable stereotactic instrument such as those commonly used in this type of surgical procedure.
  • Examples include a target-centred stereotactic frame, a frame set to polar coordinates such as the Brown- Roberts-Wells (BRW) frame, an MRI conditional frame, a surgical robot operating in a stereotactic coordinate system, or an image-guided lockable arm carrying an instrument guide 7 that is manually aligned with an image-defined trajectory.
  • a target-centred stereotactic frame a frame set to polar coordinates such as the Brown- Roberts-Wells (BRW) frame, an MRI conditional frame, a surgical robot operating in a stereotactic coordinate system, or an image-guided lockable arm carrying an instrument guide 7 that is manually aligned with an image-defined trajectory.
  • BRW Brown- Roberts-Wells
  • the instrument guide stop 5 may be an integral part of the guide, or may be separable from the guide.
  • the instrument guide stop 5 acts to provide a fixed measure of the distance from the guide’s proximal end to the datum of the stereotactic instrument. This allows the proximal end of the guide to be placed a known distance away from the skull surface or a surgical target, regardless of a position of the datum surface.
  • the guide may be configured to engage with the stereotactic instrument such that the surgical tool is aligned along a trajectory to a surgical target when it is received in the guide. This is convenient for situations where the surgical tool will be used to form tracks in the brain or implant a device along the trajectory.
  • the engagement of the instrument guide stop 5 with the datum surface may be by direct contact with the datum surface of a surface of the instrument guide stop 5 that is transverse to the length of the guide.
  • the guide can be aligned relative to the stereotactic instrument by simple mechanical placement before optionally being secured by other means such as a fastening mechanism. This removes the need for fine manual placement of the guide, for example against a graduated scale or similar, that might be required in existing solutions and which is prone to user error
  • a position of the instrument guide stop 5 on the guide is adjustable.
  • the position of the instrument guide stop 5 can be secured or locked to prevent the position changing once it is set.
  • the securing may be provided by any suitable mechanism.
  • the instrument guide stop 5 may comprise a collar clamp, as shown in Fig. 1 and Fig. 2.
  • the collar clamp is positioned around the guide and engages with the stereotactic instrument's datum surface.
  • the collar clamp can be tightened using the appropriate screw when in position.
  • other securing mechanisms may alternatively be used, such as a grub screw pressing onto the shaft of the guide.
  • the instrument guide stop 5 is illustrated in cross-sectional view in Fig 3.
  • the instrument guide stop 5 may be a cylinder with a through-bore through which the guide is inserted.
  • the instrument guide stop 5 may comprise a proximal portion 6 and a distal portion 8, the distal portion 8 having a diameter less than a diameter of the proximal portion 6.
  • the outer diameter of the instrument guide stop 5 may step down acutely from the proximal portion 6 to the distal portion 8.
  • the proximal portion 6 provides the securing mechanism to secure the instrument guide stop to the guide.
  • the proximal portion 6 is configured to engage with the datum surface of the stereotactic instrument. More specifically, the distal face of the proximal portion 6 where the diameter steps down from the proximal portion 6 to the distal portion 8 acts as a depth-stop and datum surface when it engages with the stereotactic instrument’s datum surface.
  • the outer diameter of the distal portion 8 is provided to fit closely within the instrument guide of different commercially available stereotactic instruments, such as stereotactic surgical robots and other image guided targeting devices.
  • a distal end of the reference tool is configured to engage with a skull.
  • the engagement may be direct, for example where the distal end of the reference tool contacts the skull surface This is the case for the example in which the reference tool is a datum tool 3 shown in Fig. 1 and Fig. 2.
  • the engagement may be indirect, for example where the reference tool engages with an implant or other body that is secured to the skull.
  • the guide is configured to rigidly engage with the reference tool such that a distance between a proximal end of the guide and the distal end of the reference tool is equal to a predetermined reference length, shown as length d in the example of Fig. 1.
  • a predetermined reference length shown as length d in the example of Fig. 1.
  • This provides the standardised length for surgical tools to be used with the system.
  • the position of the instrument guide stop 5 can then be adjusted and secured such that the instrument guide stop 5 engages with the datum surface of the stereotactic instrument.
  • the reference tool can be removed from the guide and the guide can subsequently be quickly and repeatedly replaced in the instrument guide 7 of the stereotactic instrument such that its proximal end is still located the predetermined reference length d from the skull surface
  • Fig. 1 and Fig 2 show an example in which the guide is a tool guide 1 and the reference tool is a datum tool 3.
  • engagement of the distal end 17 of the datum tool 3 with the skull comprises contacting a surface of the skull with the distal end 17 of the datum tool 3
  • the tool guide 1 and datum tool 3 may in particular be used as part of a tool kit for use in stereotactic neurosurgery to form a profiled hole in the skull along a trajectory, deliver a device to a target therethrough, and secure the device to the skull
  • the tool guide 1 is shown in more detail in Fig. 3 and Fig. 4.
  • the tool guide 1 comprises a throughbore configured to receive a surgical tool or the datum tool 3 for use in stereotactic surgery. Thereby, the tool guide 1 is configured to receive the surgical tool and/or the datum tool 3 in the throughbore.
  • the proximal end 2 of the tool guide 1 may further comprise a fastening mechanism 15 for engagement with a corresponding fastening mechanism on the surgical tool or datum tool 3.
  • the fastening mechanism 15 ensures that the surgical tool or datum tool 3 is securely held at the correct position along the length of the tool guide 1 when received in the throughbore For example, when the datum tool 3 is inserted into the tool guide 1, this prevents the datum tool 3 from moving proximally when the combined tool guide 1 and datum tool 3 are advanced distally such that the distal end 17 of the datum tool 3 contacts the skull surface.
  • the diameter of the throughbore of the tool guide 1 may be at least 5mm, and/or may be at most 10mm.
  • the throughbore may have a diameter of approximately 7 mm.
  • the length of the tool guide 1 may be between 100mm and 200mm, optionally approximately 150mm
  • the tool guide 1 has a length shorter than the predetermined reference length, optionally at least 2 cm shorter, optionally at least 5 cm shorter. This difference in length between the predetermined reference length and the tool guide 1 provides a working distance w between the distal end of the tool guide 1 and the skull surface, as shown in Fig 1 and Fig. 4.
  • the working distance w enables the operator to visualise the tools and devices being inserted into the cranium and, for example, suck away bone chippings generated from cutting tools.
  • the tool guide 1 further comprises a target depth stop 9 located proximally of the instrument guide stop 5
  • the target depth stop 9 provides a tool guide reference datum that provides a reference related to the datum -to-target distance of the stereotactic instrument. Specifically, a distance between a surface of the target depth stop 9 and the distal end 17 of the datum tool 3 when the datum tool 3 is engaged with the tool guide 1 is equal to a distance between the datum surface of the stereotactic instrument and the surgical target.
  • the distance from the distal face of the target depth stop 9 to the distal face of the instrument guide stop 5 equals the skull surface to target distance.
  • a position of the target depth stop 9 on the tool guide 1 may be adjustable.
  • the target depth stop 9 may comprise a collar clamp applied to the tool guide 1 , similar in construction to the proximal portion 6 of the instrument guide stop 5
  • the surface of the target depth stop 9 is the distal face in this example, but could equally be the proximal face of the clamp.
  • An adjustable target depth stop 9 allows the tool guide 1 to be used with different stereotactic instruments that may have different datum-to-target distances. However, this is not essential, and in other examples the position of the target depth stop 9 on the tool guide 1 may be fixed. The position may be chosen for compatibility with a specific stereotactic instrument with which the tool guide 1 is to be used
  • the target depth stop 9 may be the most proximal end of the tool guide 1 .
  • the target depth stop 9 may be the distal face of an acute step-down in the outer diameter of a proximal portion of the tool guide 1.
  • Fig 5 shows an example of the datum tool 3 in more detail.
  • the datum tool 3 is configured to be inserted into the throughbore of the tool guide 1 .
  • the datum tool 3 has an outer diameter sized to closely fit the diameter of the throughbore of the tool guide 1.
  • the datum tool 3 may comprise a 10mm diameter shaft
  • the datum tool 3 is used to position the proximal end 2 of the tool guide 1, guided by the instrument guide 7 of a stereotactic instrument, at the reference length d from the skull surface, preferably coaxial with a trajectory to an intracranial target.
  • the datum tool 3 is an elongated cylinder with a proximal stop 13.
  • Engagement of the datum tool 3 with the tool guide 1 during use comprises engagement of the proximal stop 13 with the proximal end 2 of the tool guide 1
  • the position of the proximal stop 13 relative to the distal end 17 of the datum tool 3 defines the predetermined reference length d More specifically, a distance between the distal end 17 of the datum tool 3 and a distal face of the proximal stop 13 is equal to the reference length d.
  • the datum tool 3 of Fig. 5 comprises a fastening mechanism 15 immediately distal to its proximal stop 13. Thereby, engagement of the datum tool 3 with the tool guide 1 during use further comprises engagement of corresponding fastening mechanisms 15 on the tool guide 1 and the datum tool 3, as discussed above in connection with the tool guide 1. By this means the datum tool 3 can be reproducibly and securely coupled to the tool guide 1.
  • the datum tool 3 comprises a handle 11 at its proximal end to allow easy handling by the user.
  • a distal region of the datum tool 3 has a reduced diameter relative to the proximal portion of the datum tool 3.
  • the distal region has a conical shape with its point at the distal end 17 of the datum tool 3. This ensures a consistent single contact point between the distal end 17 of the datum tool 3 and the skull surface.
  • the datum tool 3 may comprise one or more tracking fiducials for tracking of the position of the datum tool 3.
  • the fiducials may comprise a plurality of optical tracking fiducials.
  • optical tracking fiducials include passive retroreflective spheres or active infrared emitting diodes.
  • the fiducials enable tracking of the position and orientation of the datum tool 3 in space, for example with the optical position sensors of an image-guided, computer-assisted surgical navigation system.
  • the fiducials may be arranged in a known geometric arrangement to make them easily recognisable in an optical tracking system.
  • the fiducials may be located proximal to the proximal stop 13 so that they are not obscured when the datum tool 3 is engaged with the tool guide 1.
  • the fiducials may be provided as a permanent or integral part of the datum tool 3 during manufacture, or the fiducials may be kinematically coupled to coupling features on the datum tool 3.
  • the datum tool 3 When the datum tool 3 is registered to the surgical navigation system's 3D coordinate space, it may be used to register the position of a patients head within the same coordinate space. This can be achieved by fixing three or more fiducials directly onto the patient’s head that are visible on radiological images acquired preoperatively or intraoperatively, wherein the distal end 17 of the tracked datum tool 3 may be brought into contact with the datum on each fiducial on the patient’s head to establish their geometric relationship in the surgical navigation system’s 3D coordinate space and coregister these with their positions defined in 3D image coordinates.
  • the position of the stereotactic base frame, and thus the head can be established in the surgical navigation system’s 3D coordinate space by kinematically coupling optical tracking fiducials to the frame that have a known relationship to it This facilitates co-registration of the 3D radiological images of the patients head in the stereotactic 3D coordinate system with the registered datum tool 3 position that can be tracked and displayed in the surgical navigation system.
  • the surgical navigation system may then be used in “real time” to independently verify the setting of target trajectories in stereotactic instruments using the optically tracked datum tool 3.
  • the optically-tracked datum tool 3, as described, coupled with the tool guide 1 and instrument guide stop 5, can be positioned in the instrument guide of a multi-joint lockable arm or a haptic robot and moved to align the trajectory to a target in a patient’s head that is co-registered with, and displayed in a surgical navigation system.
  • the position of the instrument guide is then locked.
  • the position on the tool guide 1 of the instrument guide stop 5 that is in contact with the datum surface of the instrument guide is then also locked.
  • the system described above may be provided as part of a kit for use in stereotactic neurosurgery that further comprises at least one bone machining tool.
  • the bone machining tool is an example of a surgical tool that the guide is configured to receive
  • the kit may further comprise one or more device delivery tools as will be described further below
  • the bone machining tool comprises a proximal stop 13 configured to engage with the proximal end of the tool guide 1. Similar to the proximal stop 13 of the datum tool 3, this ensures that the bone machining tool adopts a known position relative to the tool guide 1 when received by the tool guide 1. This in turn allows the position of the bone machining tool relative to the skull surface to be reliably and easily set once the tool guide 1 has been set up as described above, without needing to adjust any settings of the bone machining tool itself.
  • a distance between the proximal stop 13 of the bone machining tool and a distal end of the bone machining tool is greater than the reference length by a machining distance by which the bone machining tool is intended to penetrate the skull surface during the stereotactic neurosurgery.
  • the intended machining of the skull can easily be carried out by inserting the bone machining tool into the tool guide 1 until the proximal stop of the bone machining tool engages the proximal end of the tool guide 1.
  • the step of inserting the surgical tool into the guide may comprise inserting and removing one or more bone machining tools into the guide sequentially to perform a bone machining operation.
  • Fig 9A to Fig. 9D show a plurality of cylindrical bone machining tools used to form a profiled hole in the skull
  • Each tool has a proximal stop 13 and a length between the proximal stop 13 and its distal end that is greater than the predetermined reference length d by the length by which it will penetrate the bone surface to form the profiled hole
  • the bone machining tools have proximal features 29 for attachment to surgical power tools.
  • Each bone machining tool may have a replaceable distal tip 31 that performs its machining operation. The replaceable tips make it straightforward to change the device for machining different sizes of profiled hole and for sterilisation of the tools.
  • Fig. 9A Four bone machining tools are shown in the example of Fig. 9A to Fig. 9D. These are i) a facing tool 19 (Fig 9A), ii) a pilot drill 21 (Fig. 9B), iii) a core drill 23 (Fig 9C), and a tapping tool 25 (Fig. 9D)
  • Fig. 9E also shows a device delivery tool, the guide hub delivery tool 27 with an attached guide hub 71.
  • the kit may further comprise a cranial preparation tool holder 41, as shown in Fig. 10.
  • the cranial preparation tool holder 41 is a rectangular frame which has parallel grooves in the anterior face of its upper and lower cross beams that align the tools required to form the profiled hole and insert the guide hub 71. The tools are aligned in the tool holder in order of use.
  • the datum tool 3 is held in the cranial preparation tool holder 41 within the tool guide 1
  • the tools have proximal stops 13 or other features that engage with the top surface of the cranial preparation tool holder's upper cross beam. Grooves on the lower cross beam accommodate the distal ends of the tools and are of different lengths. The length of each tool beyond the length of the datum tool 3 defines the length that it will penetrate the skull surface
  • the facing tool 19 is used to create a flat area on the generally curved surface of the skull that is orthogonal to the facing tool’s trajectory. This helps to ensure that subsequent cutting tools delivered along the same trajectory will engage the bone surface orthogonal to the trajectory, thereby minimising the likelihood of other bone machining tools skiving off axis, which could result in targeting inaccuracy.
  • the pilot drill 21 drills an initial, narrow-diameter hole to guide the core drill 23
  • the tool length of the pilot drill 23 distal to its proximal stop 13 may be independently adjusted to be greater than the predetermined reference length d by the distance from the skull surface to the inner table of the skull, or the dura along the planned trajectory. This distance can be determined from radiological images used in the planning process.
  • the core drill 23 creates the profiled hole to accommodate a device or a part thereof.
  • the core drill 23 has a coaxial pin at its distal end that is guided by the pilot hole to maintain its concentricity during cutting
  • the profiled hole may step down in diameter, to form a proximal datum surface in the bone to control the depth of insertion of devices with a rim.
  • the core drill 23 may have a step in diameter to create the step down in diameter of the profiled hole..
  • Inserted devices may be fixed in the profiled hole with an interference fit or the device may have external features that cut into the wall of the profiled hole such as a self-tapping thread or broaching teeth.
  • other bone machining tools may be delivered through the tool guide 1 such as a broaching tool or a tapping tool to cut attachment features in the wall of the profiled hole to accommodate broaching teeth or a thread on the external surface of the device.
  • the kit of Fig. 9A to 9E includes a tapping tool 25 to cut such attachment features.
  • the tapping tool 25 When the tapping tool 25 is delivered through the tool guide 1, the depth of the tap will be controlled by the engagement of the proximal stop 13 of the tapping tool 25 with the proximal end 2 of the tool guide 1. However, if the operator continues to forcibly rotate the tapping tool 25 once its proximal stop 13 contacts the proximal end 2 of the tool guide 1, then the threads cut in the bone may be stripped. To prevent this, the tapping tool 25 comprises a fastening mechanism 15 immediately distal to its proximal stop 13. This fastening mechanism 15 of the tapping tool 25 is configured to engage the corresponding fastening mechanism 15 of the tool guide 1.
  • the fastening mechanism 15 of the tapping tool 25 is a threaded section that has a matching thread pitch to the cutting threads at the distal end of the tapping tool 25.
  • the kit may further comprise one or more device delivery tools.
  • One or more devices may be inserted into the profiled hole with a corresponding device delivery tool, guided along the insertion trajectory by the tool guide 1 .
  • Fig. 9E shows a guide hub insertion tool 27, which may be used to insert the guide hub of PCT/GB2022/051104, or a similar device with a throughbore which provides a conduit and fixation means for a second device to be inserted into the brain, into the profiled hole.
  • the depth of insertion is controlled by the length of the device delivery tool between its distal end and its proximal stop 13, wherein the proximal stop 13 engages with the proximal end 2 of the tool guide 2
  • the device will be inserted by a distance equal to the length by which the length of the device delivery tool between its distal end and its proximal stop 13 exceeds the predetermined reference length.
  • the depth of insertion of the device may be controlled by a datum surface created when forming the profiled hole onto which a feature of the device, such as a rim, engages
  • a device such as a DBS lead or catheter may be inserted to its brain target through a fixation device, such as the guide hub located in the profiled hole, and then secured within it
  • the depth of device insertion may then be controlled by one or more of the engagement of the proximal stop 13 of the device delivery tool with the proximal end 2 of the tool guide 1 , a datum surface on the fixation device, or a depth stop applied to the device that engages with the proximal end of a tubular delivery tool, located in the tool guide 1 , through which it is delivered
  • Devices delivered to brain targets may also be directly fixed in the profiled hole if they have a profiled feature that is part of the device or applied to it and acts as a depth stop upon its insertion.
  • Fig 6 to Fig. 8 show an example in which the guide is a device guide 51 and the reference tool is an alignment instrument 53.
  • engagement of the distal end 17 of the alignment instrument 53 with the skull comprises engagement of the distal end 17 of the alignment instrument 53 with a guide hub 71 implanted in a skull surface
  • the device guide 51 and alignment instrument 53 may in particular be used as part of a tool kit for use in stereotactic neurosurgery to form a profiled hole in the skull along a trajectory, deliver a device to a target therethrough, and secure the device to the skull.
  • Fig 6 shows the device guide 51 with attached instrument guide stop 5.
  • Fig. 8A shows a further view of the device guide 51 with the instrument guide stop 5 removed.
  • the device guide 51 is a tube with a through-bore.
  • the device guide 51 is configured to receive a surgical tool and/or the alignment instrument 53 in the throughbore.
  • the throughbore of the device guide 51 may have a diameter of at least 5mm, optionally at least 7mm, optionally approximately 10mm.
  • the throughbore of the device guide 51 may have a diameter of at most 15mm, optionally at most 12mm.
  • the engagement of the alignment instrument 53 with the device guide 51 may comprise engagement of a proximal clamp 52 of the device guide 51 with a proximal region of the alignment instrument 53.
  • the proximal clamp 52 of the device guide 51 can also be used to fix the position of other surgical tools or devices in its bore.
  • a distal region of the device guide 51 may comprise an aperture 57 providing access to the throughbore of the device guide 51.
  • the distal end of the device guide 51 may have opposing sections of its wall removed to facilitate access to the throughbore. This can be useful if access is required to a device delivered using the device guide 51 at the skull surface during the I mp lantation/insertion procedure.
  • the distal end of the device guide 51 may comprise circumferential features for engagement with removable adapters that adapt the distal end of the device guide 51 for delivery of specific devices or surgical tools.
  • an example of such a removable adapter is the conical guide 87.
  • the system may further comprise the conical guide 87 configured to removably engage with a distal end of the device guide 51
  • the conical guide 87 reduces the diameter of a distal end of the throughbore of the device guide 51 . This may be useful during insertion of narrow devices such as a cannula 75, as will be described in more detail below, to prevent the narrow device wandering away from the centre of the profiled hole into which it is to be inserted.
  • the conical guide may reduce the diameter of the distal end of the throughbore of the device guide 51 to at most 2mm, optionally at most 1mm, optionally at most 0 5mm.
  • the conical guide 87 is split across its diameter along its axis. The two halves are held together with a sprung hinge that can be rotated to separate the halves with a finger operated actuator.
  • Fig 8B shows the alignment instrument 53.
  • the alignment instrument 53 is configured to be inserted into the throughbore of the device guide 51 .
  • the alignment instrument 53 is used to position the proximal end 2 of the device guide 51 , guided by the instrument guide 7 of a stereotactic instrument, at the reference length d from the skull surface, preferably coaxial with a trajectory to an intracranial target
  • the alignment instrument 53 further ensures that the device guide 51 adopts a known orientation relative to the guide hub 71.
  • the alignment instrument 53 is an elongated cylinder with a proximal stop 13 Engagement of the alignment instrument 53 with the device guide 51 during use comprises engagement of the proximal stop 13 with the proximal end 2 of the device guide 51
  • the position of the proximal stop 13 relative to the distal end 17 of the alignment instrument 53 defines the predetermined reference length d. More specifically, a distance between the distal end 17 of the alignment instrument 53 and a distal face of the proximal stop 13 is equal to the reference length d.
  • the proximal stop 13 engages with the proximal end 2 of the device guide 51 to prevent the alignment instrument 53 advancing further into the throughbore
  • the alignment instrument 53 has an outer diameter sized to closely fit the diameter of the throughbore of the device guide 51.
  • the alignment instrument 53 may comprise a 10mm diameter shaft.
  • the distal end 17 may be tapered to allow better visualisation of the engagement with the guide hub 71
  • the engagement of the distal end 17 of the alignment instrument 53 with the guide hub is such that the alignment instrument 53 and the guide hub 71 adopt a predetermined relative rotational alignment
  • the distal end 17 of the alignment instrument 53 comprises engagement features configured to engage with the guide hub 71 at the known relative rotational alignment.
  • the distal end of the alignment instrument 53 may comprise a bayonet fitting for engagement with the guide hub 71
  • the bayonet features engage with corresponding bayonet features in the bore of the guide hub 71
  • bayonet fittings are used in this example, and for engagement of other device delivery tools with the guide hub 71 that are discussed below, this is not essential.
  • the guide hub 71 and the tools, instruments, and other devices with which it engages may use any suitable engagement features that create a known rotational alignment between the guide hub 71 and the tool, instrument, or device when the corresponding engagement features are engaged with one another.
  • the alignment instrument 53 and the device guide 51 comprise corresponding alignment features 55.
  • the alignment features 55 are such that the alignment instrument 53 and the device guide 51 adopt a predetermined relative rotational alignment when the alignment instrument is engaged with the device guide
  • the throughbore of the device guide 51 has a channel in its wall that is aligned along the long axis of the device guide 51 .
  • the alignment instrument 53, and other surgical tools or devices configured for use with the device guide 51 comprises a rail projecting from one side of its outer diameter that fits in and is guided by the channel in the device guide 51. Thereby, the cooperation of the channel and rail acts to align cylindrical tools that are passed through the throughbore of the device guide 51.
  • the use of a rail is not essential, and other suitable features may be used on the tool. For example, one or more alignment pins may be provided on the outer diameter that fit into the channel.
  • the channel in the throughbore of the device guide 51 stops short of the distal end of the device guide 51 . This limits the depth of insertion of the alignment instrument 53 or other surgical tool or device when it is passed through the device guide 51 from the proximal end to the distal end. When the alignment instrument 53 or other surgical tool or device is inserted to the end of the channel, it projects a fixed distance from the distal end of the device guide 51.
  • the cooperating alignment features 55 establish a fixed relative rotational alignment between the alignment instrument 53 and the device guide 51.
  • the device guide 51 with its instrument guide stop 5 and engaged with the alignment instrument 51 , is then inserted into the instrument guide 7 of the stereotactic instrument.
  • the engagement features at the distal end 17 of the alignment instrument 53 are then engaged with the corresponding features on the guide hub 71 , establishing a fixed relative rotational alignment between the alignment instrument 53 and the guide hub 71. Consequently, the relative rotational alignment of the device guide 51 and the guide hub 71 is fixed, in addition to the distance of the proximal end 2 of the device guide 51 being set relative to the skull surface.
  • the position of the instrument guide stop 5 on the device guide 51 is then secured, and the instrument guide stop 5 secured in the instrument guide 7 of the stereotactic instrument Thereby, the rotational relationship between the device guide’s alignment features 55 and the guide hub 71 becomes fixed.
  • the alignment instrument 53 is subsequently withdrawn from the fixed device guide 51, other surgical tools and devices that have alignment features can be inserted into the device guide 51 These will be similarly orientated by the device guide’s alignment features 55 relative to the guide hub 71
  • the system in which the guide is a device guide 51 and the reference tool is an alignment instrument 53 may be provided as part of a kit for use in stereotactic neurosurgery.
  • the kit further comprises a surgical tool, wherein the surgical tool comprises a proximal stop 13 configured to engage with the proximal end 2 of the device guide 51 .
  • the surgical tool further comprises one or more alignment features 55 configured to engage with the alignment feature 55 of the device guide 51 such that the surgical tool and the device guide 51 adopt a predetermined relative rotational alignment when the surgical tool is engaged with the device guide 51
  • the system can be used in a method for preparing the guide for use in surgery.
  • the method comprises inserting the guide rigidly engaged with the reference tool into an instrument guide 7 of the stereotactic instrument until the distal end of the reference tool engages a skull.
  • the instrument guide 7 guides the guide rigidly engaged with the reference tool along a trajectory towards an intracranial target.
  • the guide is a tool guide 1 and the reference tool a datum tool 3
  • the distal end 17 of the datum tool 3 is passed through the throughbore of the tubular tool guide 1 until its proximal stop 13 engages the proximal end 2 of the tool guide 1.
  • the datum tool 3 coupled to the tool guide 1 is guided by the instrument guide 7 of the stereotactic instrument until the distal end 17 of the datum tool 3 engages the skull surface. Once the distal end 17 of the datum tool 3 contacts the skull surface, the proximal end 2 of the tool guide 1 will be located away from the skull surface by the predetermined reference length d.
  • the method further comprises, once the distal end of the reference tool engages the skull, adjusting the position of the instrument guide stop 5 such that the instrument guide stop 5 engages with the datum surface of the stereotactic instrument.
  • the instrument guide stop 5 is then secured or locked such that the position of the instrument guide stop 5 on the guide becomes fixed. This may be achieved using any suitable mechanism, such as the collar clamp discussed above.
  • the instrument guide stop 5 acts as a stop and provides a fixed measure of the distance from the proximal end of the guide to the datum surface of the stereotactic instrument provided by the instrument guide 7 of the stereotactic instrument.
  • the method further comprises, once the instrument guide stop 5 is secured, disengaging the reference tool from the guide.
  • the reference tool can then be removed from the guide, leaving the guide engaged with the instrument guide 7 of the stereotactic instrument, aligned coaxial with a target trajectory and with the proximal end of the guide fixed at a distance 5 from the skull surface.
  • the tool guide 1 may be shorter than the predetermined reference length d. Therefore, a space is provided between the distal end of the tool guide 1 and the skull surface by the working distance w once the datum tool 3 is removed.
  • the method further comprises, once the reference tool is disengaged from the guide, inserting the surgical tool into the guide. This allows the surgical procedure to proceed.
  • the depth of insertion of devices from the skull surface to a brain target along the planned trajectory may be determined from the surgical planning software.
  • the distance from the proximal end 2 of the tool guide 1 to the target is therefore equal to the predetermined reference length d plus the skull surface to target distance.
  • the length of track forming probes and devices required to reach their target may be adjusted with respect to a device delivery tool with a depth stop, or in the case of cannulas and catheters they may be cut to the required length to reach the target prior to their insertion
  • the kit and system described above can be used in conjunction with a device preparation jig Together, these permit the use of the relationship between the datum surfaces of the target depth stop 9, the instrument guide stop 5, and the proximal end 2 of the guide to set the length and/or insertion depth to intracranial targets of tools or devices in the device preparation jig without having to measure the lengths on a scale
  • a first example of the device preparation jig is of a similar design to that disclosed in Fig. 9 of PCT/GB2022/051104.
  • This example of the device preparation jig comprises a rectangular frame with vertical instrument and device aligning features with an upper, fixed horizontal platform that provides a datum surface referred to as the representative datum.
  • the representative datum is a datum surface representing the datum surface of the stereotactic instrument guide.
  • the device preparation jig further comprises a lower horizontal beam with a datum surface representing the target, the target datum.
  • the device preparation jig also has a horizontal platform representing the skull surface, the skull surface datum that is moveable in parallel between the representative datum and the target datum.
  • each of the tools used with the device preparation jig is fitted with a tool datum marker that is adjusted individually. Having to set many tool datum markers increases the time needed to set up the tools and increases the likelihood of error, for example if one of the tool datum markers is not properly secured.
  • the use of the system of the present invention comprising the tool guide 1 and datum tool 3 eliminates this disadvantage.
  • the coupled datum tool 3 and tool guide 1 with the secured instrument guide stop 5 When the coupled datum tool 3 and tool guide 1 with the secured instrument guide stop 5 is transferred to the device preparation jig, it is vertically aligned, and the instrument guide stop 5 is located on the representative datum
  • the skull surface datum platform is moved up to contact the distal end 17 of the datum tool 3 and the skull surface datum platform is then fixed with respect to the representative datum and target datum.
  • the tool guide 1 with secured instrument guide stop 5 may now be replaced in the stereotactic instrument and the datum tool 1 removed and set aside.
  • the distal end of device delivery tools that are vertically aligned in the device preparation jig, or features on devices to be inserted by device delivery tools, are located on to the skull surface datum platform, or may be offset from the skull surface datum, depending on the device or instrument's positional requirements.
  • the distal end of track forming probes or devices to be inserted are advanced through the device delivery tool to the target datum surface and the insertion depth is locked, for example with a collar clamp.
  • devices such as catheters and cannulas, held by the device delivery tool may be cut to the insertion length with a cutting jig positioned at the target datum.
  • the distance between the representative datum and target datum in the device preparation jig described may vary depending on the stereotactic instrument used with the present system and kit
  • the stereotactic instrument datum to target distance is fixed.
  • this distance is 190mm for the Leksell® Stereotactic instrument (Electa Solutions AB) and the Inomed® Stereotactic Ultralight System (Inomed Medizintechnik GmbH).
  • the stereotactic instrument datum to target distance can be set as required and could be set at 190mm for example for consistency with other systems
  • the device preparation jig could be constructed with a fixed distance of 190mm between the representative datum and target datum.
  • the device preparation jig may be constructed so that the position of the target datum platform can be adjusted with respect to the representative datum platform.
  • DBS deep brain stimulating
  • the DBS lead is typically a 330 or 420mm long flexible plastic tube with an outside diameter of 1 27 to 1 ,3mm that has insulated wires within its wall and several platinum-iridium electrode contacts at its distal end. A wire within its bore provides stiffness during its insertion and is removed thereafter
  • kit described above including the system comprising the tool guide 1 and datum tool 3, will be described for making a profiled hole in the skull, coaxial with a brain target, for inserting the guide hub of PCT- GB2022051104.
  • the device preparation jig 43 will also be described for use in setting the depth of insertion of a DBS lead track forming instrument and the DBS lead on a device delivery tool through the guide hub and securing it within the guide hub
  • Fig 11 A shows an example design of the guide hub 71.
  • the guide hub 71 is a hollow cylinder, which is typically manufactured from polyether ether ketone (PEEK).
  • PEEK polyether ether ketone
  • the outer diameter of the guide hub 71 steps down from a proximal region to a distal region, for example having a diameter of 6mm in the proximal region and 4mm in the distal region.
  • the guide hub 71 has a bore that has a reduced diameter at its most distal end.
  • the step in the outer diameter forms a flange that acts as a stop when it engages in a profiled hole in the skull.
  • the flange has shaped cavities 1704 in its proximal surface to receive drive features on the guide hub delivery tool 27.
  • the guide hub 71 Distal to the flange, the guide hub 71 has threads 1702 on its outer surface for engagement in the bone In its bore it has a thread for engagement with corresponding threads on a guide hub locking cap 300, the guide hub delivery tool 27, or a guide hub removal tool.
  • the transition to a reduced bore diameter at the distal end is acute and provides an internal stop and datum surface for the guide hub locking cap 300 on which a compliant silicone washer is located.
  • Fig 11 B shows an example design of the guide hub locking cap 300.
  • the guide hub locking cap 300 is a cylinder with a through bore that will accept the passage of the DBS lead
  • the outer diameter of the guide hub locking cap 300 steps down from a proximal region to a distal region, for example stepping down from 6mm to 2 5 mm.
  • the smaller diameter distal region has a thread 326 for engagement with the corresponding thread in the bore of the guide hub 71 .
  • the step in the outer diameter of the guide hub locking cap 300 outer diameter may act as a stop when the guide hub locking cap 300 is screwed into the guide hub 71.
  • the proximal surface of the guide hub locking cap 300 has radial grooves 324 which have an interference fit with drive features on the DBS lead delivery instrument 66.
  • the distal end of the guide hub locking cap 300 compresses the washer in the direction of its axis and its radial displacement grips the DBS lead to fix its position in the guide hub 71 and also creates a fluid seal.
  • Fig 10 shows the kit for forming a profiled hole in the skull coaxial with a trajectory to a brain target and inserting a guide hub 71 into the skull through the profiled hole along a planned trajectory.
  • the kit comprises: i) a datum tool 3, ii) a tool guide 1 , which comprises the instrument guide stop 5 and target depth stop 9, iii) a facing tool 19, iv) a pilot drill 21 whose drilling depth can be adjusted with a lockable collar, v) a core drill 23, vi) a tapping tool 25, and vii) a guide hub delivery tool 27 with an attached guide hub 71.
  • DBS deep brain stimulating
  • the datum tool 3 is a 7mm diameter rod with a tapered distal end and a 14mm diameter handle 11 on its proximal end
  • the distance from the distal face of the datum tool’s handle 1 1 , which acts as the proximal stop 13, to the tip of the datum tool’s distal end 17 is 200mm.
  • a male-threaded section 15 is provided just distal to the proximal stop 13 on the most proximal portion of the datum tool’s shaft
  • the tool guide 1 is a 150mm long tube with an internal diameter of 7mm.
  • the tool guide 1 has an outer diameter of 14mm.
  • the bore of the proximal end 2 of the tool guide 1 has a female-threaded portion such that when the datum tool’s male-threaded section 15 is screwed into the bore of the proximal end 2, the datum tool’s stop 13 will be brought into contact with the tool guide’s proximal end 2 and couple the tool guide 1 to the datum tool 3.
  • the tool guide 1 may have a measurement scale on its external wall indicating the distance along its length from the distal end 17 of the datum tool 3 when the tool guide 1 is coupled to the datum tool 3.
  • the target depth stop 9 is a cylindrical collar clamp that clamps to the outer diameter of the tool guide 1
  • the target depth stop 9 has an internal diameter of 14mm and is 10mm long from proximal to distal
  • the target depth stop 9 has a clamping bolt that is tightened with a torque-controlled driver.
  • the distal face of the target depth stop 9 provides the tool guide reference datum.
  • the position of the target depth stop 9 with respect to the distal end 17 of the datum tool 3 when coupled to the tool guide 1 can be fixed and measured from the scale on the tool guide 1 or fixed with reference to the scale.
  • the instrument guide stop 5 is a cylinder with a 14mm through-bore whose outer diameter steps acutely down from a proximal portion 6 to a distal portion 8.
  • the outer diameter of the distal portion 8 is provided to fit closely within the instrument guide of a stereotactic instrument.
  • the bore of the instrument guide of the stereotactic instrument may be, for example, between 18mm and 30mm in diameter.
  • the distal face of the step between the proximal portion 6 and the distal portion 8 acts as a depth stop when the instrument guide stop 5 engages with the proximal face of the instrument guide.
  • the proximal portion 6 is 10mm long and provides the clamping mechanism to clamp and secure the instrument guide stop 5 to the tool guide 1 .
  • the clamping mechanism has a clamping bolt that is tightened with a torque-controlled driver When inserted into the instrument guide, the instrument guide stop 5 and tool guide 1 are clamped in place with a finger-tightened fastener on the instrument guide.
  • the facing tool 19 is a 7mm diameter rod which steps up to a larger diameter proximal end with attachment features 29 for a power tool The step acts as a proximal stop 13 when the facing tool 19 engages with the proximal end 2 of the tool guide 1 .
  • the facing tool shaft has a detachable cutter at its distal end with a 7mm diameter cutting face positioned at 200mm distal to the proximal stop 13.
  • the cutter also has a second, concentric cutting face that is 3mm in diameter and is 1 mm distal to the first cutting face.
  • the facing tool’s first, 7mm diameter cutting face creates a flat that is orthogonal to the trajectory at the skull surface creating a datum that will engage with the guide hub’s rim to control its depth of insertion
  • the second, 3mm diameter cutting face creates a flat 1 mm into the skull surface so that the pilot drill 23 will contact a flat surface that is orthogonal to its trajectory thereby reducing the likelihood of the pilot drill 23 skiving off axis.
  • the pilot drill 21 is a 7mm diameter rod which steps up to a larger diameter proximal end with attachment features 29 for a power tool.
  • a pilot drill clamp is positioned along the shaft to control the drill’s penetration depth through the skull surface
  • the pilot drill clamp is a collar clamp, 10mm long from proximal to distal, that has a clamping bolt that is tightened with a torque-controlled driver.
  • the distal face of the clamp is adjusted against a measurement scale on the tool shaft and acts as the proximal stop 13 when it engages with the proximal end 2 of the tool guide 1 .
  • the tool shaft has a detachable 1 8mm diameter, bone cutting drill at its distal end
  • the core drill 23 is a 7mm diameter rod which steps up to a larger diameter proximal end with attachment features 29 for a power tool.
  • the step acts as a proximal stop 13 when it engages with the proximal end 2 of the tool guide 1 .
  • the tool shaft has a detachable cutter to make a profiled hole in the skull to accommodate the guide hub 71 excluding its external threads.
  • the core drill 23 has a distal coaxial pin that will enter the pilot hole in advance of the cutting elements and assists in maintaining its coaxial alignment with the trajectory during the cutting process.
  • the tapping tool 25 is a 7mm diameter rod which steps up to a larger handle 11 on its proximal end with features such as a T-bar to give the operator mechanical advantage
  • the step acts as the proximal stop 13 when it engages with the proximal end 2 of the tool guide 1 .
  • the tapping tool 25 has a male-threaded section 15 immediately distal to its proximal stop 13.
  • the tapping tool’s male-thread will engage with the female-thread in the bore of the proximal end 2 of the tool guide 1 before the tapping threads at the distal end of the tapping tool 25 contact the profiled hole in the skull.
  • the proximal male- threaded section 15 has the same pitch as the distal tapping thread so that as the tapping tool 25 is screwed into the tool guide 1 it simultaneously cuts a thread in the profiled hole in the skull.
  • the tapping tool’s proximal stop 13 contacts the proximal end 2 of the tool guide 1 further rotation of the tapping tool 25 is prevented. This informs the operator that the profiled hole has been tapped to the required depth and this also prevents stripping the cut threads in the bone.
  • the guide hub delivery tool 27 has a 7mm diameter hollow shaft which steps up to a larger handle 1 1 on its proximal end with grip features to give the operator mechanical advantage. The step acts as the proximal stop 13 when it engages with the proximal end 2 of the tool guide 1
  • the guide hub delivery tool 27 has circumferential drive features on its distal end that engage with cavities 1704 in the proximal face of the guide hub’s flange.
  • a rod passes through the central bore of the guide hub delivery tool 27.
  • the distal end of the guide hub delivery tool 27 has a male-threaded section that can be screwed into the female-thread in the guide hub’s bore using an actuating knob on the proximal end of the rod
  • the guide hub 71 When the guide hub delivery tool’s drive features are engaged in the cavities 1704 in the guide hub’s flange, and its threaded section screwed into the guide hub’s bore, the guide hub 71 is firmly fixed to the guide hub delivery tool 27.
  • the guide hub delivery tool 27 with attached guide hub 71 can be inserted down the tool guide 1 and screwed into the tapped profiled hole in the skull until the guide hub delivery tool’s proximal stop 13 engages with the proximal end 2 of the tool guide 1 At this point the guide hub 71 will be fully inserted because the flange of the guide hub 71 will engage with the datum surface that has been formed in the skull
  • the actuator knob on the guide hub delivery tool 27 is then turned anticlockwise to disengage the threads and the guide hub delivery tool 27 withdrawn, leaving the guide hub 71 in-situ.
  • the instrument guide 7 of the stereotactic instrument Prior to using the kit of the present invention to make a profiled hole in the skull and insert a guide hub 1 , the instrument guide 7 of the stereotactic instrument, fixed with respect to the head, is aligned with the planned brain target
  • the target depth stop 9 is fixed to the tool guide 1, which is engaged with the datum tool 3, so that the distance between the distal face of the target depth stop 9 and the distal end 17 of the datum tool 3 equals the stereotactic instrument’s datum to target distance.
  • This may be set using the measurement scale on the tool guide 1 or by using a jig with a fixed datum to target reference length set for the stereotactic instrument being used.
  • the instrument guide stop 5 is fixed in the instrument guide 7 and secured with a finger-tightened fastener
  • the tool guide 1 coupled to the datum tool 3 is inserted through the instrument guide stop 5 and advanced until the distal end 17 of the datum tool 3 touches the skull surface after it has been exposed through a small scalp incision.
  • the datum tool 3 is disengaged and withdrawn from the tool guide 1
  • the distal end of the tool guide 1 is now separated by the working distance w, which in this case is 50mm, from the skull surface entry point.
  • the working distance allows the operator to visualise tools engaging with the operative site and suck away bone chippings and fluid.
  • the first cutting tool inserted down the tool guide 1 is the facing tool 19.
  • the facing tool 19 is attached to a power tool and used to create a flat on the skull surface so that the pilot drill 21 will engage with the skull orthogonally.
  • the distance from the skull surface to the inner table of the skull, along the selected trajectory, is established from the radiological images used for trajectory planning. This required depth of skull penetration is set on the pilot drill’s proximal shaft by moving the proximal stop 13 of the pilot drill 21 with reference to a scale on the shaft and locking it off.
  • the pilot drill 21 is connected to a power tool and inserted down the tool guide 1 until the proximal stop 13 of the pilot drill 21 acts as a depth stop when it engages the proximal end 2 of the tool guide 1 .
  • a core drill 23 attached to a power tool is then used to create a profiled hole that has a datum surface in the skull onto which the rim of the guide hub 71 will be seated when inserted, the core drill 23 has a distal coaxial pin that enters the pilot hole in advance of the cutting elements and assists in maintaining coaxial alignment with the trajectory during the cutting process.
  • the tapping tool 25 is now delivered down the tool guide 1 until its male-threaded section 15 engages with the female thread in the bore of the proximal end 2 of the tool guide 1 .
  • the proximal male-thread 15 has the same pitch as the distal tapping thread so that as the tapping tool 25 is screwed into the tool guide 1 it simultaneously cuts a thread in the profiled hole in the skull
  • the tapping tool’s proximal stop 13 engages the proximal end 2 of the tool guide 1 further rotation of the tapping tool 25 is prevented by the threaded section 15, which informs the operator that the profiled hole has been tapped to the required depth This also prevents stripping the cut threads in the bone.
  • the tapping tool 25 is then unscrewed and withdrawn from the tool guide 1.
  • a guide hub 71 is fixed to the distal end of the guide hub delivery tool 27, as described above, and may be loaded onto the guide hub delivery tool 27 directly from its sterile packaging without the operator touching the device by hand.
  • the guide hub delivery tool 27 with the attached guide hub 71 is inserted down the tool guide 1 and screwed into the tapped profiled hole in the skull until the guide hub delivery tool’s proximal stop 13 engages with the proximal end 1 of the tool guide 1
  • the guide hub delivery tool 27 is then withdrawn, after disengaging with the guide hub 71, leaving the guide hub 71 in situ.
  • the distance between the datum surfaces of the target depth stop 9 and the instrument guide stop 5 fixed to the tool guide 1 equals the skull surface to target distance.
  • the tool guide 1 can therefore be used as a measuring device to set the insertion depth of the DBS lead track forming instrument 61 and the DBS lead in the device preparation jig 43, as will be described further below
  • the tool guide 1 can be removed from the instrument guide 7 of the stereotactic instrument and transferred to the device preparation jig 43 to set the insertion depths after insertion of the guide hub 71 , or immediately after fixing the position of the instrument guide stop 5 and before the cutting tools are used In the latter case, after using the tool guide 1 to set the device preparation jig 43, the tool guide 1 may be repositioned in the instrument guide 7, and the skull drilling and guide hub 71 insertion can be carried out by the operating surgeon in parallel to an assistant setting the insertion depths of the DBS lead and its delivery instrument. This would be a more time-efficient workflow.
  • Fig 12 shows an embodiment of the device preparation jig 43 for use in the delivery of the DBS lead
  • the device preparation jig 43 is a rectangular frame for setting the depth of insertion of instruments required for inserting devices and setting the length of devices that will be inserted into a patient during surgery.
  • This embodiment may be used with the tool guide 1 comprising a target depth stop 9 that provides a tool guide reference datum.
  • the distance between the distal end 17 of the datum tool 3 and the tool guide reference datum equals the distance between the datum surface of the stereotactic instrument and the surgical target Therefore, once the position of the instrument guide stop 5 is secured after it has been set with the tool guide 1 engaged with the datum tool 3 touching the skull surface, the skull surface to target distance is measurable on the tool guide 1 between the tool guide reference datum and the instrument guide stop 5.
  • the skull surface to target distance can be set directly by positioning the tool guide 1 between one fixed and one moveable cross beam.
  • the device preparation jig 43 comprises vertical instrument and device aligning features, a fixed horizontal platform 47 with a datum surface representing the skull surface datum, and a moveable horizontal platform 45 that can be moved in parallel with the skull surface datum representing the target datum on guide rods and can be clamped in position.
  • the distance between the skull surface datum and the target datum may be measured with a measurement scale 44 attached to, and moved with, the target datum.
  • the tool guide 1 with the secured instrument guide stop 5, with or without the coupled datum tool 3, is positioned in the device preparation jig 43 so that the tool guide reference datum surface of the target depth stop 9 is in contact with the skull surface datum and the moveable horizontal platform 45 representing the target datum is moved to contact the instrument guide stop 5
  • the position of the target datum is then locked with a suitable fastening mechanism.
  • the device delivery tools are vertically aligned in the device preparation jig 43 so that their distal ends are located on the skull surface datum.
  • the distal end of track forming probes or devices to be inserted are advanced through the corresponding device delivery tool to the target datum and the insertion depth is locked, for example with a clamp.
  • the skull surface datum has receiving features for the distal end of the DBS lead track forming instrument 61 and the guide hub locking cap 300 that is located on the distal end of the DBS lead delivery instrument 66
  • the receiving features may be offset from the skull surface datum.
  • the guide hub 71 may be counter sunk so that its proximal surface is 0.5 mm below the skull surface, wherein the distal face of the DBS lead track forming instrument 61 which contacts the guide hub surface will engage with the skull surface datum 0.5mm below its reference datum.
  • the device delivery tools of the kit further comprise, in addition to the guide hub delivery tool 27, a device guide 51 , DBS lead track forming instrument 61 , and DBS lead delivery instrument 66. These are illustrated in further detail in Fig 13A to Fig. 13C.
  • the device guide 51 is a 130 mm long tube with a 10mm bore and an OD of 14 mm except for its proximal 8mm which has an OD of 18mm, wherein the step created acts as a depth stop.
  • the device guide 51 has a finger-operable proximal clamp 52 to fix the longitudinal position of instruments in its bore.
  • the device guide 51 comprises an instrument guide stop 5 configured to engage with a datum surface of a stereotactic instrument.
  • a single instrument guide stop 5 may be used for both the tool guide 1 and the device guide 51, where the instrument guide stop 5 is detachable from the tool guide 1 and device guide 51 and can transferred between them However, this is not essential, and the tool guide 1 and device guide 51 may each have their own instrument guide stop 5.
  • the body of the DBS lead track forming instrument 61 is a 190mm long tube, the greater part of which has a 10mm OD to fit within the bore of the device guide 51.
  • the proximal 10mm of the DBS lead track forming instrument 61 has an OD of 14mm, and the step created acts as a depth stop.
  • the distal end of the DBS lead track forming instrument 61 tapers to a 6mm diameter section whose distal face will contact the proximal datum face of the guide hub 71
  • the bore of the DBS lead track forming instrument 61 guides a shaft 62 with a 1 .3 mm diameter track forming probe 63 attached to its distal end.
  • the track forming probe 63 is guided by a 1.35mm hole in the distal end of the DBS lead track forming instrument 61 that is contiguous with its bore
  • a collar clamp 64 on the shaft 62 acts as a depth stop for the track forming probe 63.
  • a finger- operable proximal clamp 65 on the proximal end of the DBS lead track forming instrument 61 clamps the shaft 62 and allows the operator to control and fix the depth of insertion of the track forming probe 63 up to the stop
  • the track forming probe 63 has a distal tip that is profiled to pass with minimal tissue trauma, as described in PCT/GB2022/051101 .
  • the DBS lead delivery instrument 66 is a 190mm long tube with an internal diameter of 1.35 mm and an outside diameter, the greater part of which is 10mm to fit within the bore of the device guide 51
  • the DBS lead delivery instrument 66 has a 10mm long proximal section that has an OD of 14 mm and the step formed acts as a proximal depth stop 68.
  • the OD of the cylindrical actuator 67 in its proximal portion is 10mm and it tapers to a 6mm OD distally
  • the proximal portion of the actuator 67 has vertical ribs to improve finger grip.
  • the distal end of the actuator 67 has radially disposed teeth that have an interference fit in radial grooves 324 on the proximal face of the guide hub locking cap 300. The teeth are used to impart a rotatory force on the guide hub locking cap 300 to screw the male-thread of the guide hub locking cap 300 into the female thread in the bore of the guide hub 71 and compress the washer in the base of the guide hub 71.
  • the tool guide 1 with the secured instrument guide stop 5 and target depth stop 9, with or without the coupled datum tool 3, is inserted into the device preparation jig 43.
  • the distal face of the target depth stop 9 is located on the device preparation jig s skull surface datum.
  • the moveable horizontal platform 45 representing the target datum is moved vertically so that the target datum surface contacts the datum surface on the instrument guide stop 5.
  • the position of the moveable horizontal platform 45 is then locked with a suitable fastening mechanism such as a clamp.
  • the tool guide 1 may then be replaced in the stereotactic instrument.
  • the DBS lead track forming instrument 61 is inserted into the device guide 51 up to its proximal stop and fixed in position with the clamp 52 on the proximal end of the device guide 51 .
  • the coupled device guide 51 and DBS lead track forming instrument 61 are located into the device preparation jig 43 so that the proximal end of the device guide 51 is aligned in grooves in the jig’s upper platform and the distal end of the DBS lead track forming instrument 61 is located in features on the fixed horizontal platform 47 representing the skull surface datum.
  • the track forming probe 63 is now advanced to the target datum surface and the collar clamp 64, whose distal face is in contact with the proximal end of the body of the DBS lead track forming instrument 61 , is locked with a torque screwdriver.
  • the track forming probe 63 is now drawn back into the body of the DBS lead track forming instrument 61 and the proximal clamp 65 locked.
  • the DBS lead delivery instrument 66 is inserted into the device preparation jig 43 so that its proximal depth stop 68 is located on a datum surface on the jig’s upper platform and the DBS lead delivery instrument 66 is aligned in the device preparation jig’s alignment features.
  • the datum surface on the guide hub locking cap 300 that is located on the distal end of the DBS lead delivery instrument’s actuator 67 is now positioned in receiving features on the skull surface datum.
  • the DBS lead 69 is inserted through the proximal end of the DBS lead delivery instrument 66 until it contacts the target datum surface, and a stop is applied to the DBS lead 69 whose distal face contacts the proximal end of the DBS lead delivery instrument 66
  • the DBS lead track forming instrument 61 coupled to the device guide 51 is delivered through the instrument guide stop 5 until its distal end contacts the proximal datum surface of the guide hub 71 that has been fixed in the skull.
  • a single instrument guide stop 5 may be shared between the tool guide 1 and device guide 51.
  • the instrument guide stop 5 may be detached from the tool guide 1 , transferred back to the instrument guide 7 of the stereotactic instrument, and fixed to it The instrument guide stop 5 is then clamped to the device guide 51 (coupled to the DBS lead track forming instrument 61) which fixes the proximal end of the device guide 51 at the appropriate distance (in this specific example being 180mm) from the guide hub datum surface.
  • the proximal clamp 65 of the DBS lead track forming instrument 61 is released and the track forming probe 63 is advanced until the collar clamp 64 on its shaft 62 contacts the proximal end of the DBS lead track forming instrument 61
  • the track forming probe 63 is then withdrawn into the body of the DBS lead track forming instrument 61 and the position of the track forming probe 63 clamped again with the proximal clamp 65.
  • a track for inserting the DBS lead 69 has now been created in the brain and the DBS lead track forming instrument 61 is withdrawn from the device guide 51.
  • the DBS lead delivery instrument 66 with the clamped DBS lead 69 removed is inserted through the device guide 51 until its proximal stop 68 contacts the proximal end of the device guide 51.
  • the threads on the distal end of the guide hub locking cap 300 are now in contact with the threads in the bore of the guide hub 71 and the actuator 67 on the distal end of the DBS lead delivery instrument 66 will have been displaced proximally.
  • the DBS lead 69 is inserted through the proximal end of the DBS lead delivery instrument 66 until its stop contacts the proximal end of the DBS lead delivery instrument 66.
  • the distal end of the DBS lead 69 is now at the planned target.
  • the actuator 67 is rotated, which screws the guide hub locking cap 300 into the guide hub 71 and compresses the washer in the distal bore of the guide hub 71 whose internal diameter is reduced to firmly grip the DBS lead 69
  • the stylet in the bore of the DBS lead 69 is withdrawn, the stop on the DBS lead 69 is removed, as is the DBS lead delivery instrument 66 This leaves the DBS lead 69 fixed in the guide hub 71 and thus secured to the skull.
  • the DBS lead 69 may be bent by 90° in the guide tube locking cap 300 and held with an interference fit in one of the guide tube locking cap's radial grooves 324, ensuring a low-profile fixation, with improved cosmesis and a reduced risk of scalp erosion when the wound is closed over the implanted devices.
  • the DBS lead 69 may be removed by reopening the scalp wound over the implant and mobilising the DBS lead 69 proximal to the guide hub fixation and lifting it out of its interference fit in the radial grooves 324 in the guide hub locking cap 300 Using a hollow screwdriver with a side slot as described in PCT/GB2022/051104, the guide hub locking cap 300 may be unscrewed and the DBS lead 69 withdrawn from the brain, the guide hub 71 may be removed using the guide hub removal tool also described in PCT/GB2022/051104.
  • the system disclosed above will now be described in a further embodiment suitable for the delivery of a cannula assembly to a brain target and securing the cannula assembly to the skull for the purpose of delivering a drug to a brain target using convection enhanced delivery.
  • the cannula assembly comprises a guide hub 71 such as that disclosed in PCT/GB2022/051104 and shown in Fig. 11 A, and a guide tube 73 and cannula 75 such as disclosed in PCT/GB2022/051101.
  • the kit for forming a profiled hole in the skull coaxial with a brain target as described above is used in this procedure along with device delivery tools for inserting the guide hub 71.
  • a further embodiment of the device preparation jig 43 is also used for setting the length of the guide tube 73 and cannula 75 and the corresponding device delivery tools for insertion through the guide hub 71 and fixation of the devices in the skull.
  • the dimensions provided here are exemplary only, and other dimension may be used as appropriate depending on the specific application
  • Fig 14A to Fig. 14C show the cannula assembly.
  • Fig. 14A shows the component parts and
  • Fig. 14B shows the components assembled together
  • Fig. 14C shows a cross-section through the assembled components in the region of the guide hub 71
  • the guide hub 71 is as described above.
  • the outer diameter of the guide hub 71 steps down from 5mm in the proximal region to 4mm in the distal region In the proximal bore, the guide hub 71 has bayonet fitting features In the wall of the distal bore, the guide hub 71 has vertical channels that have an interference fit with the guide hub delivery tool 27, or a guide hub removal tool
  • the guide tube 73 for insertion into the brain has a proximal end and a distal end with a through-bore for the passage of a cannula 75.
  • the guide tube 73 is made of cuttable plastic wherein the inner layer is stiff with air vent holes and the outer layer is electro-spun hydrophobic plastic or a plastic/ silicone composite that is resiliently deformable and porous to allow passage of air.
  • the inner diameter of the guide tube is 0.5mm and the uncompressed outer diameter of the guide tube 73 is 1.3mm.
  • the proximal end of the guide tube 73 is expanded to a diameter of 2.5mm to form a cap that can be retained in the distal bore of the guide hub 71
  • the cannula 75 is a fine cuttable plastic tube, made of PEEK, with an outer diameter of about 0 5mm and an inner diameter of about 0 2mm.
  • the cannula 75 has a stop 76 positioned between its proximal and distal ends.
  • the stop 76 has bayonet fitting features which lock into the bayonet fitting features in the proximal end of the guide hub 71.
  • the stop 76 also has a silicone washer that forms a fluid seal with the guide hub 71.
  • the stop 76 has radial grooves in its proximal face that have an interference fit with the distal end of the cannula delivery instrument 85.
  • the cannula 75 has a proximal connector 77 for connection to an infusion line.
  • the cannula's proximal connector 77 has an integrated gas and bacteria filter.
  • An extension tube 74 extends from the stop 76 to the proximal connector. The diameter of the extension tube may be greater than the diameter of the cannula distal to the stop 76. This provides greater resilience in the section of the cannula 75 that will be external to the skull.
  • the kit for forming a profiled hole in the skull coaxial with a trajectory to a brain target and inserting a guide hub 71 is substantially the same as already shown in Fig. 10 and discussed in connection with the implantation of the DBS lead 69 above.
  • the facing tool 19 in this embodiment has a first cutting face of 6mm diameter and the proximal cutting face of the core drill 23 is also 6mm in diameter.
  • the guide hub delivery tool 27 in this embodiment is a 7mm diameter rod which steps up to a larger handle 11 on its proximal end with grip features to give the operator mechanical advantage.
  • the guide hub delivery tool 27 has engagement features on its distal end that engage with corresponding engagement features in the bore of the guide hub 71 with an interference fit.
  • the engagement features at the distal end of the guide hub delivery tool 27 may, for example, be vertical ribs disposed around its circumference that fit into vertical slots around the inner diameter of the bore of the guide hub 71.
  • the distance between the datum surfaces of the target depth stop 9 and the instrument guide stop 5 fixed to the tool guide 1 equals the skull surface to target distance.
  • the tool guide 1 can therefore be used as a measuring device to set the insertion depth of the guide tube 73 and cannula 75, and the tools to deliver them in the device preparation jig 43.
  • the requirements for preparing the guide tube 73 for insertion to the brain target are:
  • the guide tube 73 should be cut to a length such that, when inserted into the guide hub 71, the distal end of the guide tube 73 will be at a predetermined depth with respect to the skull datum
  • the distal end of the guide tube 73 should be cut cleanly and truly orthogonal to its axis This can be difficult to achieve due to the deformability of the electro-spun outer layer of the guide tube 73. 3) Preparation and insertion of the guide tube should be achieved without the guide tube 73 being directly touched by the operator.
  • the no-touch technique reduces the likelihood of device contamination, and thereby complications such as infection
  • the guide tube 73 should be inserted down a pre-made track in the tissue.
  • the track will be created with a track forming probe 84 that has a profile that produces minimal trauma when inserted into brain tissue.
  • the guide tube 73 should be inserted with a rigid probe in its bore having a similar outer diameter to the cannula 75 During insertion, the rounded distal end of the probe will project just beyond the distal end of the guide tube 73. Once inserted, the probe will be advanced to the brain target to create a track for the target
  • the requirements for preparing the cannula 75 for insertion to the brain target are:
  • the cannula 75 is cut to a length such that when inserted into the guide hub 71 , the distal end of the cannula 75 will be at a predetermined depth with respect to the skull datum.
  • the predetermined depth for the cannula 75 is typically deeper than for the guide tube 73.
  • the cannula 75 will be inserted down the guide tube 73 and then into a pre-made track in the tissue to its predetermined target.
  • the cannula 75 When the cannula 75 is secured in the guide hub 71 with its bayonet fitting, the cannula 75 should not rotate around its long axis by more than 60° to minimise tissue trauma.
  • the requirements for the preparation and insertion of the guide tube 73 and cannula 75 are met by the provision of a further embodiment of the device preparation jig 43 in addition to a further set of device delivery tools of the kit.
  • the device delivery tools for implanting the cannula assembly comprise i) a device guide 51 , ii) a conical guide 87, ill) a device guide alignment instrument 53, iv) a guide tube track forming instrument 81, v) a guide tube delivery instrument 83, and vi) a cannula delivery instrument 85.
  • Fig 15 shows an embodiment of the device preparation jig 43 for use in the delivery of the cannula assembly.
  • the device preparation jig 43 comprises instrument and device retention and aligning features in a top crossbeam, a fixed horizontal platform 47 with a datum surface representing the skull surface datum, and a moveable horizontal platform 45 representing the target datum.
  • the guide tube 73 and cannula 75 are inserted to different depths along the same trajectory.
  • the guide tube 73 is inserted short of the target, and the cannula 75 inserted through the guide tube 73 to the target.
  • a second horizontal and moveable platform 46 may be positioned between the skull surface datum and the target datum which provides a reference surface, the reference datum.
  • the device delivery tools are vertically aligned in the device preparation jig 43 so that their distal ends are located on the skull surface datum.
  • the skull surface datum has receiving features for the device delivery tools, which may be offset from the surface, depending on the device or instrument’s positional requirements.
  • the distal end of track forming probes or devices to be inserted are advanced through the corresponding device delivery tool to the target datum or the reference datum and the insertion depth is locked, for example with a clamp.
  • Devices such as the guide tube 73 and cannula 75, held by the corresponding device delivery tool are also be cut to the required insertion length with a cutting jig positioned at the target datum
  • the device delivery tools are inserted sequentially through the device guide 51 to deliver the device to the intracranial target
  • the device delivery tools of the kit further comprise, in addition to the guide hub delivery tool 27, a device guide 51, a guide tube track forming instrument 81, a guide tube delivery instrument 83, and a cannula delivery instrument 85 These are illustrated in further detail in Fig 16A to Fig 18B
  • Fig 16A to Fig. 16D show the guide tube track forming instrument 81.
  • the guide tube track forming instrument 81 is a 10mm diameter tube with a tapered distal end and alignment features 55 projecting from one side of its circumference.
  • the bore of the guide tube track forming instrument 81 guides a shaft 82 with a 1 ,2mm diameter probe 84 attached to its distal end.
  • Fig 16A shows the guide tube track forming instrument 81 with the probe 84 retracted into the body of the guide tube track forming instrument 81 .
  • Fig. 16B shows the probe 84 extended beyond the distal end of the guide tube track forming instrument 81.
  • a clamp 86 applied on the proximal end of the shaft 82 acts as a stop as the shaft 82 is passed from the proximal end of the guide tube track forming instrument 81 towards the distal end.
  • the clamp 86 controls the length of the probe 84 that projects beyond the tapered distal end of the guide tube track forming instrument 81, and thereby the length of the track formed by the probe as it is inserted into the brain.
  • the position of the shaft 82 in the guide tube track forming instrument 81 can be locked with a finger tightened actuator at the proximal end of the guide tube track forming instrument 81.
  • Fig 16C shows detail of the disassembled components of the guide tube track forming instrument 81.
  • the bore of the distal end 17 of the guide tube track forming instrument al guides the probe 84 coaxial with the guide tube track forming instrument al .
  • Fig. 16D shows further detail of the connection of the probe 84 to the shaft 82 at the distal end 17.
  • the probe 84 has a distal tip that is profiled to pass with minimal tissue trauma, as described in PCT/GB2022/051101
  • the guide tube delivery instrument 83 has a construction that is very similar to the guide tube track forming instrument 81, but has a narrower probe for forming the track into which the cannula 75 will extend past the end of the guide tube 73 after implantation.
  • the probe is also used to support the guide tube 73 during delivery, as will be described in more detail below.
  • the guide tube delivery instrument 83 is a 10 mm diameter tube with alignment features 55 projecting from one side of its circumference. Attached to the distal end 17 of the guide tube delivery instrument 83 is a tapered section with a tubular distal end with vertical grooves in its outer diameter.
  • the bore of the guide tube delivery instrument 83 guides a shaft 82 with a 0.5mm diameter probe 84 attached to its distal end.
  • a clamp 86 applied on the proximal end of the shaft 82 acts as a stop as the shaft 82 is passed from the proximal towards the distal end of the guide tube delivery instrument 83. The position of the clamp 86 on the shaft 82 controls the length of the probe 84 that projects beyond the distal end of the guide tube delivery instrument 83.
  • the bore of the guide tube delivery instrument 83 at its distal end 17 coaxially guides the probe 84
  • the position of the shaft 82 in the tube can be locked with a finger tightened actuator at the proximal end of the guide tube delivery instrument 83.
  • the probe 84 has a rounded distal tip so that its profile causes minimal trauma as it is passed through brain tissue.
  • Fig 17A and Fig. 17B show the cannula delivery instrument 85.
  • the cannula delivery instrument 85 is a 10mm diameter plastic shaft with alignment features 55 projecting from one side of its circumference.
  • the cannula delivery instrument 85 has a hollow distal end 17 with opposing apertures 57 in its wall to gain access to, and remove from one side, the cannula’s proximal connector 77 which is located in the hollow section.
  • the distal end 17 of the cannula delivery instrument 85 has a reduced diameter and has a radial slot to accommodate the extension tube of the cannula 75.
  • the slot is contiguous with the hollow section of the cannula delivery instrument 85 so that the cannula’s extension tube 74 and proximal connector 77 can be removed from the cannula delivery instrument 85 after the cannula has been inserted into the skull and the stop 76 secured into the guide hub 71
  • the distal end 17 of the cannula delivery instrument 85 has radially disposed teeth configured to have an interference fit in radial grooves on the proximal face of the cannula stop 76.
  • the teeth are used to impart a rotatory force on the stop 76 to lock its bayonet features into the corresponding bayonet features of the guide hub 71.
  • the teeth also retain the cannula 75 on the shaft of the cannula delivery instrument 85 until the teeth are forcibly disengaged from the stop 76 when the stop 76 is locked in the guide hub 71.
  • the insertion depth of the device delivery tools and corresponding devices are first set in the device preparation jig 43 shown in Fig. 15.
  • the tool guide 1 with the secured instrument guide stop 5 and target depth stop 9, with or without the coupled datum tool 3, is inserted into the device preparation jig 43
  • the distal face of the target depth stop 9 is located on the device preparation jig’s skull surface datum.
  • the moveable horizontal platform 45 representing the target datum is moved vertically so that the target datum surface contacts the datum surface on the instrument guide stop 5.
  • the position of the moveable horizontal platform 45 is then locked with a suitable fastening mechanism such as a clamp. This sets the distance between the skull surface datum and the target datum in the device preparation jig 43
  • the guide tube 73 When a guide tube 73 is to be inserted along the same trajectory as the cannula 75, the guide tube 73 will be inserted to a distance short of the target.
  • the planned distance from the distal end of the guide tube 73 to the target (the step length) is set in the device preparation jig 43 by moving the second horizontal and moveable platform 46 that provides the reference datum.
  • the reference datum is moved to a position above the target datum by the step length distance with reference to a measurement scale 44 that is fixed to the first moveable horizontal platform 45.
  • the tool guide 1 with the secured instrument guide stop 5 and target depth stop 9, with or without the coupled datum tool 3, is removed from the device preparation jig 43.
  • the tool guide 1 can then be repositioned and secured in the instrument guide 7 of the stereotactic instrument.
  • Preparation of the device and device delivery tools in the device preparation jig 43 by an operative may now occur in parallel with cranial preparation using the bone machining tools for insertion of a guide hub 71 by the surgeon.
  • the probe 84 of the guide tube track forming instrument 81 is withdrawn into the body of the guide tube track forming instrument 81 .
  • the probe 84 of the guide tube delivery instrument 83 is withdrawn into the body of the guide tube delivery instrument 83.
  • the device delivery tools are positioned in the device preparation jig 43 in order of use from left to right.
  • the proximal ends of the device delivery instruments are located and aligned by features in the top crossbeam.
  • the distal ends are located in the corresponding receiving features in the skull surface datum.
  • the distal tip of the probe 84 of the guide tube track forming instrument 81 is advanced to touch the surface of the reference datum.
  • the length of the probe 84 is locked off with the clamp 86.
  • the probe 84 is then withdrawn back into the instrument and the position fixed with the proximal clamp of the guide tube track forming instrument 81
  • the guide tube 73 preferably in a protective sleeve, is held by the guide tube delivery instrument 83 with the probe 84 of the guide tube delivery instrument 83 withdrawn into the body of the guide tube delivery instrument 83.
  • the guide tube 73 is cut horizontally in the device preparation jig 43 with a cutting tool 91 in line with the reference datum.
  • Fig 18 shows the cutting tool 91 and its components in more detail.
  • the cutting tool 91 comprises a mounted blade 93 and parallel rods 95 positioned on each side.
  • the rods 95 are guided by channels 97 in the device preparation jib 43 that align the blade 93 orthogonal to the guide tube 73 This ensures that the end of the guide tube 73 is cut cleanly and truly orthogonal to its longitudinal axis.
  • Fig. 20A and Fig. 20B illustrate the cutting of the guide tube 73 in situ in the device preparation jig 43.
  • the guide tube delivery instrument 83 is now moved to the right side of the device preparation jig 43 to set the insertion depth of the probe 84 of the guide tube delivery instrument 83, which passes through the bore of the guide tube 73 to the target depth.
  • the proximal end of the guide tube delivery instrument 83 is located in retention and alignment features in the device preparation jig’s top crossbeam.
  • the distal end of the guide tube delivery instrument 83 is located in receiving features in the skull surface datum platform above the target datum platform 45
  • the probe 84 of the guide tube delivery instrument 83 for forming the cannula track is advanced through the guide tube 73 to contact the target datum.
  • the clamp 86 on the shaft 82 of the guide tube delivery instrument 83 is locked off.
  • the probe 84 is then withdrawn so that only its tip projects beyond the distal cut end of the guide tube 73. This means that the probe 84 of the guide tube delivery instrument 83 will support the guide tube 73 during insertion, but will not form the cannula track until it is extended again
  • the position of the probe 84 is fixed with the clamp 76 on the proximal end of the guide tube delivery instrument 83.
  • the cannula 75 is held in the cannula delivery instrument 85, extending through the target datum platform 45.
  • the cutting tool 91 is moved from the reference datum platform 46 to further guide channels 97 in the target datum platform 45.
  • the cutting tool 91 is then used to cut the cannula 75 horizontally at the level of the target datum, as illustrated in Fig. 22A and Fig. 22B.
  • the cannula 75 is now primed with infusate.
  • the infusate is preferably an inert fluid such as artificial CSF (aCSF) or phosphate buffer solution (PBS).
  • aCSF artificial CSF
  • PBS phosphate buffer solution
  • the infusion is achieved by displacing the proximal connector 77 of the cannula 75 out of the hollow distal end 17 of the cannula delivery instrument 85 through the one of the apertures 57, as illustrated in Fig. 23A.
  • the infusate can then be injected into the cannula 75 through the connector 77 as illustrated in Fig. 23B.
  • the proximal connector 77 is repositioned in the distal end 17 of the cannula delivery instrument 85.
  • the alignment instrument 53 coupled with the device guide 51 having the instrument guide stop 5, is removed from the device preparation jig 43 and inserted through the instrument guide 7 of the stereotactic instrument
  • the position of the instrument guide stop 5 on the device guide 51 is adjusted until the engagement features at the distal end 17 of the alignment instrument 53 contacts the proximal end of the guide hub 71 that has previously been implanted in the patient’s skull as described above.
  • the alignment instrument 53 is rotated around its axis until the engagement features, which are typically bayonet fittings, drop into and engage with the corresponding engagement features, e.g. bayonet features, in the bore of the guide hub 71.
  • the position of the instrument guide stop 5 on the device guide 51 is now fixed and the alignment instrument 53 is withdrawn from the device guide 51.
  • the working distance which is typically 50mm provides a working space below the device guide 51 for the operator to visualise the delivery of instruments and devices into the guide hub 71.
  • the orientation of the alignment features 55 in the bore of the device guide 51 is also fixed with respect to the guide hub 71 , so that instruments and devices with alignment features 55 that are subsequently passed through the device guide 51 will be similarly aligned with respect to the guide hub 71.
  • the fixed orientation ensures that, for example, when the cannula 75 is delivered with the cannula delivery instrument 85, the male-bayonets on the cannula stop 76 will already be aligned with the corresponding bayonet features in the guide hub 71. This facilitates controlled delivery of the cannula 75 to its target and avoids the need for the operator to excessively rotate the cannula delivery instrument 85 to “feel” for the alignment of the bayonet elements, which may traumatise the brain tissue at the distal end of the cannula 75
  • the guide tube track forming instrument al is inserted through the device guide 51 until its distal end 17 contacts the datum surface on the guide hub 71.
  • the proximal clamp on the guide tube track forming instrument al is released and the probe 84 of the guide tube track forming instrument 81 is advanced until the clamp 86 on the shaft 82 contacts the proximal end of the guide tube track forming instrument 81 .
  • the probe 84 is then withdrawn back into the body of the guide tube track forming instrument 81 , the proximal clamp is re-applied, and the guide tube track forming instrument al is withdrawn from the device guide 51.
  • the guide tube delivery instrument 83 with its attached guide tube 73 is inserted down the device guide 51 until the guide tube 73 contacts the guide hub’s internal stop.
  • the proximal clamp on the guide tube delivery instrument 83 is released and the probe 84 of the guide tube delivery instrument 83 is advanced until the clamp 86 on its shaft 82 contacts the proximal end of the guide tube delivery instrument 83
  • the probe 84 is then withdrawn back into the body of the guide tube delivery instrument 83 and the position of the probe once again fixed with the proximal clamp of the guide tube delivery instrument 83.
  • the guide tube delivery instrument 83 is withdrawn from the device guide 51 , leaving the guide tube 73 in- situ and a prepared track in the tissue distal to the distal end of the guide tube 73 into which the cannula 75 will be delivered.
  • the cannula delivery instrument 85 is inserted through the device guide 51 with the cannula 75 withdrawn into the body of the cannula delivery instrument 85.
  • the device guide 51 aligns the bayonet features on the cannula stop 76 with the bayonet features in the guide hub 71
  • the conical guide 87 is attached to the distal end of the device guide 51 to assist in aligning the narrow cannula 75, which typically has an outer diameter of 0.5mm.
  • the cannula 75 is then advanced through the cannula delivery instrument 85 into the guide tube 73.
  • the conical guide allows the cannula to be inserted into the bore of the guide tube 75 bore without handling by the operator that may otherwise be needed to align the cannula 75 with the guide tube 73.
  • the cannula 75 is then advanced until the bayonets on its stop 76 have entered the corresponding bayonet features in the guide hub 71 and contacted their most distal surface.
  • the alignment features 55 on the cannula delivery instrument 85 are distally placed on the body of the cannula delivery instrument 85 and are shorter in length than those on the alignment instrument 53. This means that, once the cannula delivery instrument 85 is fully advanced and the cannula stop 76 engaged with the guide hub 71 , the alignment features 55 on the cannula delivery instrument 85 no longer restrict rotation of the cannula delivery instrument 85. Once the cannula delivery instrument 85 is released from its guidance in the device guide 51 , this enables the operator to rotate the cannula delivery instrument 85 to lock the bayonet fittings on the stop 76 with those on the guide hub 71. This is illustrated in Fig. 26C.
  • the aperture 57 at the distal end of the cannula delivery instrument 85 provides access to the cannula’s proximal connector 77 With the stop 76 fully engaged with the guide hub 71 , the proximal connector 77 and extension tube 74 can be disengaged from the cannula delivery instrument 85 and ejected from the cannula delivery instrument 85, as shown in Fig. 26D.
  • the device guide 51 with attached instrument guide stop 5 and the cannula delivery instrument 85 are withdrawn together, detaching the interference fit of the radially disposed teeth of the distal end of the cannula delivery instrument 85 from the radial slots in the proximal face of the cannula stop 76. This leaves the cannula 75 fully inserted in the guide hub 71 with its connector 77 ready for use, as shown in Fig. 27.

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Abstract

L'invention concerne un système destiné à être utilisé en neurochirurgie stéréotaxique. Le système comprend un guide et un outil de référence. Le guide est conçu pour recevoir un outil chirurgical destiné à être utilisé lors d'une intervention stéréotaxique et comprend une butée de guidage d'instrument conçue pour venir en prise avec une surface de référence d'un instrument stéréotaxique. Une position de la butée de guidage d'instrument sur le guide est réglable. Une extrémité distale de l'outil de référence est configurée pour venir en prise avec un crâne. Le guide est configuré pour venir en prise de manière rigide avec l'outil de référence de telle sorte qu'une distance entre une extrémité proximale du guide et l'extrémité distale de l'outil de référence est égale à une longueur de référence prédéterminée. L'invention concerne également un procédé d'utilisation du système.
PCT/EP2025/062104 2024-05-14 2025-05-02 Appareil et procédé d'insertion de dispositif intracrânien et de fixation de crâne Pending WO2025237702A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB2406765.4 2024-05-14
GBGB2406765.4A GB202406765D0 (en) 2024-05-14 2024-05-14 Apparatus and method for intracranial device insertion and skull fixation

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WO2025237702A1 true WO2025237702A1 (fr) 2025-11-20

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080275466A1 (en) * 2007-05-01 2008-11-06 James Grant Skakoon Dual cannula system and method for using same
US20110009879A1 (en) * 2007-10-08 2011-01-13 Renishaw (Ireland) Limited Apparatus for stereotactic neurosurgery
US20140371711A1 (en) * 2013-06-17 2014-12-18 Alcyone Lifesciences, Inc. Methods and devices for protecting catheter tips and stereotactic fixtures for microcatheters
US20210244478A1 (en) * 2020-02-07 2021-08-12 Medos International Sarl Navigational arrays and related methods for use with a robotic arm
WO2022229662A1 (fr) 2021-04-30 2022-11-03 Neurochase Technologies Limited Dispositif de guidage implantable

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080275466A1 (en) * 2007-05-01 2008-11-06 James Grant Skakoon Dual cannula system and method for using same
US20110009879A1 (en) * 2007-10-08 2011-01-13 Renishaw (Ireland) Limited Apparatus for stereotactic neurosurgery
US20140371711A1 (en) * 2013-06-17 2014-12-18 Alcyone Lifesciences, Inc. Methods and devices for protecting catheter tips and stereotactic fixtures for microcatheters
US20210244478A1 (en) * 2020-02-07 2021-08-12 Medos International Sarl Navigational arrays and related methods for use with a robotic arm
WO2022229662A1 (fr) 2021-04-30 2022-11-03 Neurochase Technologies Limited Dispositif de guidage implantable

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