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WO2001089378A1 - Electrode de type aiguille destinee a une electromyographie - Google Patents

Electrode de type aiguille destinee a une electromyographie Download PDF

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Publication number
WO2001089378A1
WO2001089378A1 PCT/DK2001/000357 DK0100357W WO0189378A1 WO 2001089378 A1 WO2001089378 A1 WO 2001089378A1 DK 0100357 W DK0100357 W DK 0100357W WO 0189378 A1 WO0189378 A1 WO 0189378A1
Authority
WO
WIPO (PCT)
Prior art keywords
core
electrode
needle electrode
needle
metal salt
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.)
Ceased
Application number
PCT/DK2001/000357
Other languages
English (en)
Inventor
Jan Paustian
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.)
Medicotest AS
Original Assignee
Medicotest AS
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 Medicotest AS filed Critical Medicotest AS
Priority to AU2001260088A priority Critical patent/AU2001260088A1/en
Publication of WO2001089378A1 publication Critical patent/WO2001089378A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/25—Bioelectric electrodes therefor
    • A61B5/279—Bioelectric electrodes therefor specially adapted for particular uses
    • A61B5/296—Bioelectric electrodes therefor specially adapted for particular uses for electromyography [EMG]
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
    • A61B2562/02—Details of sensors specially adapted for in-vivo measurements
    • A61B2562/0209—Special features of electrodes classified in A61B5/24, A61B5/25, A61B5/283, A61B5/291, A61B5/296, A61B5/053
    • A61B2562/0215—Silver or silver chloride containing
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
    • A61B2562/02—Details of sensors specially adapted for in-vivo measurements
    • A61B2562/0209—Special features of electrodes classified in A61B5/24, A61B5/25, A61B5/283, A61B5/291, A61B5/296, A61B5/053
    • A61B2562/0217—Electrolyte containing

Definitions

  • the present invention relates to a needle electrode suitable for electromyography (EMG) . Furthermore, the invention relates to a process for the preparation of a needle electrode.
  • EMG electromyography
  • CNE concentric needle electrodes
  • EMG diagnostic clinical electromyogram
  • the CNE is used to gather information about the bio-electrical condition of a muscle.
  • the needle end of the CNE is introduced through the skin and into the muscle fibre of interest. If the CNE is properly inserted into a motor unit of a muscle, the action potential signal can be measured by the tip of the needle.
  • the electrode is connected to an electrical appliance suitable for converting electrical signals measured by the CNE into an electromyogram.
  • the parameters of the motor unit action potential examined in diagnostic EMG are known to vary with the physical properties of the CNE. Also, properties of the CNEs contribute to the technical quality of EMG recordings. Therefore, to obtain a high quality recording, it is essential to use a CNE having a design and choice of construction optimising the measurement of the individual parameters.
  • the electrical characteristics of a CNE influencing the final electromyogram are inter alia impedance and noise generation.
  • the design and use of materials at the tip of the CNE is of major importance for the impedance. For instance, it is known that an increased area of the core surface decreases the impedance. However, increasing the diameter of the needle to allow for an increase of the core surface area is only suitable to a certain extent due to patience . compliance. Furthermore, the desirability to record from only a small number of muscle fibres establish an upper boundary on the suitable core surface area.
  • the needle electrode can be connected as cathode and treated in 10 seconds at a frequency of 20 to 100 Hz.
  • electrolytical treatment is in many cases transient and the effect of the treatment is quickly reduced during handling or wetting of the electrode tip.
  • the electrolytical treatment should be performed within a few hours prior to the use of the CNE and the CNE should be subjected to a minimum of handling during the time interval between treatment and application. If the electrolytical treatment is prepared immediately prior to use an improvement of the reduction of the impedance of 1.5 to 4 times can be reached.
  • the electrolytical treatment was extensively used for the multi-use CNEs. However, to-day most clinics uses presterilised, disposable, ready-for-use CNEs. The preferential use of disposable (or single-use) CNEs has halted the procedure of electrolytical treatment, properly because the procedure is time consuming and involves an extra procedural step before the recording of an electromyogram. Therefore, the disposable electrodes essentially show the same relatively high impedance as the CNEs for multi-use. The high impedance and the variation thereof among individual electrodes from the same manufacture generates noise on the measurements and uncertainties on the results. The generation of noise is at least partly due to a high impedance because the CNE functions as an antenna.
  • the major sources of noise influencing the final electromyogram are ambient, i.e. external to the patient .
  • the electro-magnetic radiations from the various electrical appliances and lights in a modern clinic is recorded by the CNE.
  • the noise is in the lower frequence range, i.e. about 50 or 60 Hz.
  • a low impedance should preferentially be present at the lower frequency range.
  • MAP catheter In the remote technical area of measuring electrical signals in the cardiac cavity, it has been suggested in US 4.922.912 to use a monophasic action potential (MAP) catheter comprising a pair of Ag-AgCl electrodes.
  • the MAP catheter is adapted to be guided into the body through a flexible liner and is hardly usable as a needle electrode because one of the Ag-AgCl electrodes is projecting at a peripheral surface. This design will hamper insertion of the electrode or at least be unpleasant for the patient.
  • MAP catheters are not suitable for skeletal muscles . They have their major use in the measuring of electrical signals in smooth muscles, such as the heart.
  • the geometrical design of the electrode may change the shape of the recorded electromyogram, such that a direct comparison with a recording from a CNE electrode would not be possible.
  • the present invention concerns a needle electrode for electromyography, comprising an electrically- conductive core separated from an external cannula by an electrically insulating material, said needle electrode, at a first end, being adapted for introduction into a tissue and comprising an exposed surface of the core and, at a second end, being adapted for establishing electrical contact with an electrical appliance suitable for providing an electromyogram, wherein, at the first end, the surface of the core is provided with a layer of a metal salt.
  • the electrically conductive core can be of any- suitable conducting material . Examples of suitable materials are platinum, platinum alloy, stainless steel, nickel/chromium alloy, iridium and silver. Silver is generally preferred due to the eminent conductive abilities thereof and the relatively low price .
  • the electrically conductive core is separated from the external cannula by an electrically insulating material.
  • an electrically insulating material such as polyethylene, polyvinylchloride or a varnish, is applied to the core throughout the entire longitudinal direction.
  • the core covered by the electrically insulating material is fixed inside the external cannula by a suitable adhesive.
  • a suitable adhesive is preferably an electrically insulating material.
  • a preferred adhesive is of the epoxy type.
  • the external cannula suitably is used as the reference electrode an electrically conductive material having the desired electrical and physical characteristics is generally used.
  • the electrically conductive material for the cannula is prepared of metal or metal alloy.
  • An example of a preferred material for the cannula is stainless steel. If an external reference electrode is used, however, any non-conducting material having the desired physical characteristics may, in principle, be used.
  • the exposed surface of the core is suitable provided by cutting the assembly provided of the core, electrically insulating material and the external cannula at a desired angle. If the angle relative to the longitudinal direction of the assembly is 90° the area of the exposed core surface is the lowest possible ensuring a local measurement. However, it is in general desired to cut the cannula in an angle of 10° to 45° relative to the longitudinal direction of the assembly to increase the core surface area and to provide the needle with a sharp point making it easier to introduce the needle into the skin. When cut at an angle of less than 90° the geometric form of the core surface is an ellipse. The elliptic core is coaxially surrounded by the electrically isolating material and the external cannula, hence the reference electrode.
  • the surface area of the core is typically 0.02 to 2 mm 2 , preferably 0.05 to 1 mm 2 .
  • the surface of the core is provided with a layer of metal salt.
  • the metal salt is preferably a metal halide, such as metal chloride, metal bromide, or metal iodide.
  • the metal of the metal salt is preferably of a type also present in the core. Examples of the metal in the metal salt are silver, chromium, iron, nickel, copper, and platinum. Specific examples of suitable metal salts are AgCl , AgBr, CuCl 2 , CuBr 2 , ZnCl 2 , and FeCl 3 .
  • the metal salt is AgCl .
  • the cannula is constructed of a metal or a metal alloy and has an area larger that the surface of the core, due to the fact that the impedance per square metre is higher for the metal or metal alloy compared to the metal salt .
  • the area of the cannula and the core is selected so as to compensate for any irregularity in impedance .
  • the metal salt can be provided on the core in any suitable way.
  • the metal salt can be provided on the core by compressing an amorphous metal salt, sputtering or electrolytical application.
  • the metal salt is provided on the core by electrolytical application.
  • the invention does also pertain to a process for the preparation of a needle electrode, comprising the steps of i) providing a needle electrode comprising an electrically conductive core separated from an external cannula by an electrically insulating material, said needle electrode, at a first end, being adapted for introduction into a tissue and comprising an exposed surface of the core and, at a second end, being adapted for establishing electrical contact with an electrical appliance suitable for providing an electromyogram, ii) immersing a part of the needle electrode comprising the first end into an electrolyte, iii) connecting the core of the needle electrode to a power source as anode and an auxiliary electrode as cathode, and iv) energising the power source to produce a layer of a metal salt at the exposed core surface.
  • the electrolyte may be any media with the ability to conduct the current therein.
  • the electrolyte is aqueous.
  • the electrolyte preferably contains the anion of the metal salt to be formed on the exposed core surface .
  • the anion may be any one which forms a metal salt on the core surface suitable for measurement of a motor unit action potential. Suitable anions are halide ions, such as chloride, bromide and iodide ions.
  • a preferred anion in the electrolyte solution is the chloride ion (Cl " ) .
  • the anion can be provided in the electrolyte solution in any suitable way. By way of example the anion may be provided by dissolution of a salt containing the anion or by providing the corresponding acid.
  • the anion is provided in the electrolyte solution by adding the corresponding acid to a suitable amount of water, because the acidic nature of the electrolyte accelerates the deposition of metal salt during the electrolysis.
  • Suitable acids are HC1, HBr, and HI, preferably HCl .
  • the electrically conductive core can be of any suitable conducting material .
  • suitable materials are platinum, platinum alloy, stainless steel, nickel/chromium alloy, iridium, and silver. Silver is generally preferred due to the eminent conductive abilities thereof and the relatively low price.
  • the metal of the core is converted during the electrolysis process to the cation of the metal salt formed on the surface of the core .
  • the auxiliary electrode may be any electrically conductive material. -Furthermore, the auxiliary electrode may be insoluble or soluble during energising of the power source. Suitable examples of insoluble auxiliary electrodes are electrodes containing carbon, silver, palladium and/or platinum. Suitable examples of soluble auxiliary electrodes are electrodes containing aluminium, zinc, magnesium and/or lead. Soluble electrodes may be suitable if a metallic anion is desired. However, preferably the auxiliary electrode is insoluble and the metal of the core is used as the metal cation of the metal salt to be formed on the surface of the core. The auxiliary electrode is present in the same electrolyte solution as the needle electrode, however, without direct physical contact.
  • the electrical contact between the needle electrode and the auxiliary electrode is conveyed by the electrolyte solution.
  • the power source for the electrolytical process is a DC power source .
  • the core of the needle electrode is connected to the positive pole as anode and the auxiliary electrode is connected to the negative pole as the cathode. Following the connection of the electrodes the power source is energised.
  • a suitable current and voltage is selected in accordance with the selected materials and design of the needle electrode, the auxiliary electrode as well as the composition of the electrolyte. The skilled person can easily select a suitable current and voltage through simple trial and error experimentation.
  • anode reaction (I) and the cathode reaction (II) is as follows :
  • anode reaction (I) AgCl is deposited at the surface of the core of the needle electrode and, in accordance with the cathode reaction (II) , hydrogen gas is liberated at the cathode .
  • the metal of the core is transformed to the cation of the metal salt during the electrolysis process, a suitable electrical contact between the metal salt and the core metal is believed to occur.
  • the treatment time is decisive for the amount of metal salt formed on the surface of the core if the current and the voltage has been fixed.
  • the thickness of the layer of metal salt provided on the surface of the core can be estimated as the charge supplied per surface area of the core .
  • the charge supplied per surface area of the core is at least 200, preferably 400 mC/cm 2
  • the maximum charge supplied per surface area of the core preferably does not extent 4000, preferably 1500, and most preferred 1000 mC/cm 2 .
  • the initial needle electrode used for application of a layer of metal salt at the surface of the core, may be provided in any suitable way securing that the core is electrically insulated from the external cannula.
  • a conveniently way of producing the initial electrode is to cover a wire of the material desired for the core with an electrically insulating material of, e.g. a plastic material such as polyvinylchloride
  • the covered wire is provided in the interior of the cannula and the intervening space between the covered core and the interior of the cannula is at least partly filled with an adhesive having a sufficient low viscosity to be able to flow from the outside into the intervening space. Subsequently the assembly is allowed to cure and the end thereof intended to be introduced into the subject is cut in a desired angle and ground to expose the core surface. The second end of the assembly is provided with a connecting plug able to engage with a corresponding connecting wire. The connecting wire connects the assembly with the appliance able to transform the measured signals into an electromyogram.
  • the external cannula is adapted for connection as a reference electrode, while the core is adapted for connection as a measurement electrode.
  • an external electrode as reference electrode.
  • the external electrode may be introduced in the tissue next to the needle electrode or elsewhere in the body of the subject, or the external electrode may be immersed in a reference solution.
  • a non-invasive electrode may be used as reference electrode.
  • the non- invasive reference electrode may be placed on the skin or a mucous membrane of the subject. As an example, when the non-invasive reference electrode is placed on the skin, electrodes of the type used for electrocardiography may be used.
  • the needle electrode according to the present invention shows excellent low impedances at high as well as low frequencies.
  • the improvement of the needle electrodes according to the invention is most pronounced for the low frequencies, however, improvements throughout the whole frequency range is observed.
  • the variation among electrodes prepared in accordance with the same procedure is remarkable low indicating that less variability among the individual needle electrodes occur when a layer of metal salt is provided on the exposed core.
  • a needle comprising a silver core and an external cannula of stainless steel was prepared by inserting a silver wire covered by an electrical isolating varnish into the lumen of the cannula and subsequently fixing the silver wire to the interior of the cannula walls with an epoxy adhesive.
  • the tip of the cannula was cut and ground in a angle of about 15 degrees relative to the longitudinal direction of the needle.
  • the area of the exposed surface of the core on the tip was 0.00068 cm 2 .
  • said electrode is referred to as an untreated needle electrode.
  • the tip of the needle was immersed in a solution of 21 ml HC1 (37%) in 500 ml demineralised water.
  • the pH of the solution was 0.42 and the temperature was 22°C.
  • an auxiliary electrode of silver was provided in the solution.
  • a DC power supply unit was provided and the core of the cannula was connected as anode and the auxiliary silver electrode was connected as cathode.
  • the charge supplied to the exposed area of the core of the needle was used as an indicator for the amount of deposited silver chloride at the tip of the cannula and calculated as:
  • the impedance of the needles treated as described above was measured for two frequencies, viz. 10 Hz and 10kHz. A signal generator generating a sinus curve was used. In the circuit a resistor of 1 MOhm was included.
  • the noise is approximately 1/10 for the treated needle electrodes compared to the untreated. Moreover, the standard derivation is less for the treated needle electrodes compared to the untreated ones, indicating that less variability among the individual needle electrodes occur for the treated ones .

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  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Medical Informatics (AREA)
  • Biophysics (AREA)
  • Pathology (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Physics & Mathematics (AREA)
  • Molecular Biology (AREA)
  • Surgery (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)

Abstract

L'invention concerne une électrode, de type aiguille, destinée à une électromyographie, et comprenant une âme électroconductrice séparée d'une canule extérieure par un matériau isolant électriquement; en outre cette électrode est conçue, au niveau d'une première extrémité, pour être introduite dans un tissu et pour exposer une surface de son âme, et au niveau d'une seconde extrémité pour établir un contact électrique avec un appareil électrique approprié à la production d'un électromyogramme, et elle est caractérisée en ce qu'au niveau de la première extrémité, la surface de l'âme est pourvue d'une couche d'un sel métallique. Par ailleurs, cette électrode possède une faible impédance.
PCT/DK2001/000357 2000-05-24 2001-05-23 Electrode de type aiguille destinee a une electromyographie Ceased WO2001089378A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2001260088A AU2001260088A1 (en) 2000-05-24 2001-05-23 Needle electrode for electromyography

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DKPA200000825 2000-05-24
DKPA200000825 2000-05-24

Publications (1)

Publication Number Publication Date
WO2001089378A1 true WO2001089378A1 (fr) 2001-11-29

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Family Applications (1)

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PCT/DK2001/000357 Ceased WO2001089378A1 (fr) 2000-05-24 2001-05-23 Electrode de type aiguille destinee a une electromyographie

Country Status (2)

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AU (1) AU2001260088A1 (fr)
WO (1) WO2001089378A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013134776A1 (fr) * 2012-03-09 2013-09-12 Natus Medical Incorporated Aiguille concentrique d'électromyographie de performance
CN108324273A (zh) * 2017-05-16 2018-07-27 南京医科大学第附属医院 一种肌电检查针
RU2756673C1 (ru) * 2021-03-23 2021-10-04 Федеральное государственное бюджетное образовательное учреждение высшего образования "Ивановский государственный химико-технологический университет" Раствор для электрохимической анодной обработки поверхности электродов из серебра
WO2023028195A1 (fr) * 2021-08-25 2023-03-02 Drexel University Aiguilles emg tressées multi-électrode pour électrodiagnostics avancés

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4235241A (en) * 1977-09-08 1980-11-25 Tdk Electronics Co., Ltd. Electrodes for living body
US4847980A (en) * 1987-11-16 1989-07-18 The Governors Of The University Of Alberta Method of manufacturing transmural cardiac electrodes
US4922912A (en) * 1987-10-21 1990-05-08 Hideto Watanabe MAP catheter
WO1998025518A1 (fr) * 1996-12-13 1998-06-18 Medelec Limited Aiguille et sonde a aiguille

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4235241A (en) * 1977-09-08 1980-11-25 Tdk Electronics Co., Ltd. Electrodes for living body
US4922912A (en) * 1987-10-21 1990-05-08 Hideto Watanabe MAP catheter
US4847980A (en) * 1987-11-16 1989-07-18 The Governors Of The University Of Alberta Method of manufacturing transmural cardiac electrodes
WO1998025518A1 (fr) * 1996-12-13 1998-06-18 Medelec Limited Aiguille et sonde a aiguille

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013134776A1 (fr) * 2012-03-09 2013-09-12 Natus Medical Incorporated Aiguille concentrique d'électromyographie de performance
CN108324273A (zh) * 2017-05-16 2018-07-27 南京医科大学第附属医院 一种肌电检查针
CN108324273B (zh) * 2017-05-16 2023-11-28 南京医科大学第一附属医院 一种肌电检查针
RU2756673C1 (ru) * 2021-03-23 2021-10-04 Федеральное государственное бюджетное образовательное учреждение высшего образования "Ивановский государственный химико-технологический университет" Раствор для электрохимической анодной обработки поверхности электродов из серебра
WO2023028195A1 (fr) * 2021-08-25 2023-03-02 Drexel University Aiguilles emg tressées multi-électrode pour électrodiagnostics avancés

Also Published As

Publication number Publication date
AU2001260088A1 (en) 2001-12-03

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