RU2789981C1 - Method for microsurgical access from low-traumatic medium suboccypital craniotomy to negolams of the posterior cranious fosture - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to medicine, namely to neurosurgery. A linear vertical incision of the skin and soft tissues of the cervical-occipital region is performed, 6 cm long. In this case, the incision begins 0.5 cm below the external occipital protrusion and continues down to the level of the spinous process of the second cervical vertebra. After preparation and retraction of soft tissues, an asymmetric osteoplastic trepanation is performed from one burr hole, installed along the midline 2.5 cm from the edge of the foramen magnum. The formed bone flap measuring 2.5 by 2 cm, including the posterior semicircle of the foramen magnum, is left on the intact posterior atlantooccipital membrane. The dura mater is dissected with an arcuate incision 1.5 cm long with its base facing the occipital sinus, which is not transected. One-sided preparation of the gap between the uvula of the worm and the tonsil of the cerebellum is carried out from top to bottom and medially to the level of the foramen of Mogendie, focusing on the inferior vein of the vermis, the posterior tonsil vein and the place of transition of the telelotonsillar segment of the posterior inferior cerebellar artery to its cortical segment.

EFFECT: method allows to improve the results of surgical treatment, reduce soft tissue injuries in the area of the craniovertebral junction, provide an adequate view of all parts of the IV ventricle and the rhomboid fossa, reduce the risk of postoperative liquorrhea due to hermetic suturing of the dura mater and preservation of the atlantooccipital joint, accelerate the activation of patients after surgery, reduce length of stay of patients in the hospital, reduce the cost of treatment.

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Description

The invention relates to medicine, namely to neurosurgery, and can be used in the treatment of tumors in the median localization of the posterior cranial fossa. Pathologies of this localization include neoplasms of the brainstem, vascular and ependymal lining of the IV ventricle, vermis, and medial parts of the cerebellar hemispheres. By histological nature, these formations can be represented by: astrocytomas of varying degrees of malignancy, ependymomas, subependymomas, medulloblastomas, choroidpapillomas, hemangioblastomas, dermoid cysts, and choroid plexus meningiomas.

Currently, the main approach for the treatment of such formations is median suboccipital craniotomy with access to the cavity of the IV ventricle through the foramen of Mogendie. Access is performed both in the position of the patient sitting on the operating table, and lying on his side or on his stomach. A median incision of the skin and soft tissues is made, 10-15 cm long, which starts 1-2 cm above the external occipital protrusion and continues in the caudal direction to the level of the spinous processes of the third or fourth cervical vertebra. Next, a wide dissection of the muscles is performed from the midline to the sides. From the occipital bone and the arch of the first cervical vertebra, the trapezius, semispinalis and small rectus muscles of the head are dissected. Extensive osteoplastic or resection trepanation is performed from two burr holes installed directly under the external protrusion of the large occipital bone on both sides of the midline. The trepanation includes the posterior edge of the foramen magnum. Additionally, the arch of the first cervical vertebra and the spinous process of the second cervical vertebra can be resected to increase the surgical viewing angle. The dura mater is opened with a Y-shaped or U-shaped incision over the hemispheres of the cerebellum and the large occipital cistern, while the partially functioning occipital sinus is transected. After removing the CSF from the large occipital cistern, access is made to the cavity of the IV ventricle through the foramen of Mogendi. To expand the space, either the choroid plexus in the region of the roof of the fourth ventricle, or the lower sections of the cerebellar vermis, or the vascular lining in the gap between the tonsil of the cerebellum and the brain stem or uvula of the cerebellar vermis are additionally partially dissected [1].

Despite its widespread use, this access has a number of significant disadvantages [2]:

- firstly, extensive trepanation is associated with muscle injury, intersection of the nerves innervating the skin and soft tissues of the cervical-occipital region, as well as the risk of damage to the venous sinuses and diploid veins, which leads to massive blood loss during surgery or the development of an air embolism, if the patient is operated on in a sitting position;

- secondly, injury to a large array of muscles and violation of the integrity of the posterior complex in the region of the craniovertebral junction, which includes the back of the foramen magnum, the arch of the first cervical vertebra and the posterior atlantooccipital membrane, during skeletonization leads to muscle atrophy and instability of the described segment in the distant postoperative period. Clinically, this is manifested by discomfort in the cervical-occipital region, restriction of movement and, in some cases, the development of torticollis;

- thirdly, difficulties and lack of complete tightness when suturing a large incision of the dura mater often lead to the development of wound liquors (up to 27%) [3]-[5] or the accumulation of liquor in the soft tissues of the neck, both in the early and late postoperative period;

- fourthly, traction or dissection of the cerebellar vermis, as well as preparation of the gap between the tonsil and the cerebellar vermis on both sides can lead to the appearance of mutism in the early postoperative period [4], [6]-[8];

- fifthly, the direction of the surgical approach at an acute angle to the plane of the rhomboid fossa, especially in cases of removal of intramedullary tumors of the brainstem, leads to excessive damage to the tegmentum of the brainstem due to its tension, which contributes to the aggravation of neurological symptoms after surgery.

In connection with the above features, in recent years (since 2008), minimally invasive (“keyhole”) approaches to the posterior cranial fossa have been introduced into practice, when a small craniotomy is performed from a small incision of the skin and soft tissues. Reducing the size of trepanation helps to reduce the number of dissected muscles. The size of the trepanation itself, more often resectional, according to various authors, varies from 3 cm to 14 mm [9]-[12].

Such surgeries are usually performed with the patient in pronation position on the operating table. From a small incision of the skin and soft tissues, a craniotomy is performed in the form of resection of the posterior half-ring of the foramen magnum and part of the scales of the occipital bone. This removes the posterior atlantooccipital membrane, and sometimes part of the dorsum of the first cervical vertebra. A small Y-shaped, U-shaped or linear incision is made in the dura mater above the cerebellar tonsils and cistern major [11], [12]. Due to the narrowness of the surgical approach, it is not possible to perform a complete preparation of the gaps between the tonsil, brainstem, and cerebellar vermis to improve the view of the surgical field. In this connection, the authors limit themselves to only incising the choroid plexus in the area of the foramen of Mogendi in order to separate the cerebellar tonsil slightly to the sides. An insignificant view of the surgical field allows leveling endoscopic assistance, but this requires a complete set of both rigid and flexible endoscopes with different viewing angles, a good light source and a digital video camera [13], [14]. The endoscope is inserted into the cavity of the IV ventricle through the median aperture in the rostral direction. Suction and microinstruments are located under the endoscope. After removal of the tumor, the dura mater is sutured and additionally strengthened with artificial materials, since it is not always possible to achieve hermetic suturing. Subsequently, soft tissues are sutured in layers.

Despite a decrease in soft tissue trauma and a decrease in the risk of damage to large venous collectors, the minimally invasive approaches offered today to median neoplasms of the posterior cranial fossa do not solve a number of significant problems, in particular:

- due to resection of bone structures and the posterior atlantooccipital membrane, the risk of developing instability in the craniovertebral junction remains;

- the narrowness of the surgical access does not allow a good examination of the surgical field, and in some cases creates inconvenience for hermetic suturing of the dura mater;

- "keyhole" accesses do not allow changing the angle of surgical attack when removing brainstem formations.

In other words, a minimally traumatic surgical approach to neoplasms of the median localization of the posterior cranial fossa, which allows tumor removal with an adequate viewing angle, convenient suturing of the dura mater and, at the same time, maximally preserving the anatomical structures of the craniovertebral junction, would significantly improve the results of surgical treatment and the quality of life of patients with this condition. pathology.

As a prototype, the method of standard suboccipital median craniotomy using an intraoperative microscope was chosen [1].

We have developed a new method of microsurgical access from low-traumatic median suboccipital craniotomy to neoplasms of the posterior cranial fossa.

The purpose of the proposed invention is to reduce the morbidity of surgery, reduce the number of intraoperative and postoperative complications while maintaining adequate visualization of the IV ventricle and dorsal brain stem when accessing neoplasms of the posterior cranial fossa.

The goal is achieved by:

1) Reducing the area of trepanation;

2) Performing asymmetric (more on the access side) osteoplastic trepanation from one burr hole with preservation of the posterior atlantooccipital membrane;

3) Application of an arcuate incision of the dura mater 1.5 cm long on the side of surgical access without crossing the occipital sinus;

4) Use of unilateral microsurgical access through the gap between the tongue of the worm and the cerebellar tonsil (uvulotonsillar fissure).

The approach we propose can be carried out with the patient on the operating table lying on his stomach, or in a sitting position, or on his side, opposite from the side of the surgical approach. The patient's prone position is preferred. The patient's head is fixed in the Mayfield bracket and is located strictly in the midline, without rotation, the neck is bent as much as possible, but the distance between the chin and the sternum should not be less than 2 cm (Fig. 1). A linear vertical incision of the skin and soft tissues of the cervical-occipital region, 6 cm long, begins 0.5 cm below the external occipital protrusion and continues down to the level of the spinous process of the second cervical vertebra (Fig. 2). Subsequently, with the help of monopolar coagulation, the semispinous and small rectus muscles of the neck are partially dissected from the scales of the occipital bone from the level of the lower nuchal line, the posterior half-ring of the foramen magnum and the arch of the first cervical vertebra from the midline and to the sides asymmetrically. The preparation of soft tissues is carried out asymmetrically on the side where the gap between the tongue of the worm and the tonsil of the cerebellum will be further prepared. After the retractors of the soft tissues are retracted to the sides, one burr hole is installed along the midline at a distance of 2.5 cm from the edge of the foramen magnum. To avoid damage to the dura mater during trepanation, the remnants of the internal occipital crest are resected using size 2 or 3 pistol nippers. Osteoplastic trepanation is performed asymmetrically on the side where the gap between the tongue of the worm and the tonsil of the cerebellum will be further prepared using a craniotome. A bone flap measuring 2.5 by 2.0 cm is formed, which includes the posterior semicircle of the foramen magnum (Fig. 3). The obtained bone flap on the preserved posterior atlantooccipital membrane is retracted in the caudal direction, fixed and remains in the surgical field, while the posterior atlantooccipital membrane is not damaged. On the side of the surgical approach, the dura mater is dissected by an arcuate incision 1.5 cm long with its base facing the occipital sinus and retracted to the opposite side from the surgical approach on two handles (Fig. 4). The occipital sinus does not intersect and remains intact. The arachnoid membrane of the upper sections of the large occipital cistern is dissected linearly. After the cerebrospinal fluid is removed, a one-sided preparation of the gap between the uvula of the vermis and the cerebellar tonsil (uvulotonsillar fissure) is performed from top to bottom and medially to the level of the foramen of Mogendie (Fig. 5: A, B). The anatomical landmark for the beginning of the gap preparation is the place of transition of the inferior vein of the vermis (vena vermis inferior) into the posterior tonsil vein (vena retrotonsillaris) (Fig. 5: B). Also in this place, the telelotonsillar segment of the posterior inferior cerebellar artery passes into its cortical segment, which is also an anatomical landmark. The gap is prepared along the telelotonsillar segment of the posterior inferior cerebellar artery. After the tonsil and lower sections of the cerebellar vermis are separated to the sides with the help of microspatulas, the vascular lining (tela choroidea) of the roof of the IV ventricle is widely exposed from the entrance to it and up to the upper velum and lateral eversion on the side of the surgical approach (Fig. 5: B) . The vascular lining is dissected while preserving the branches of the posterior inferior cerebellar artery, which supply the blood supply to the choroid plexus of the IV ventricle (Fig. 5: A, D). The cavity of the IV ventricle and the rhomboid fossa are partially exposed (Fig. 5: E). The following anatomical formations of the bottom of the IV ventricle are visualized: the superior fossa (fovea superior), the mound of the facial nerve (colliculus facialis), the medial eminence (eminentia medialis), the brain strips (striae medullares), the triangle of the hypoglossal nerve (trigonum hypoglossus) and the inferior cerebellar peduncle. By changing the viewing angle of the operating microscope (up to 45 degrees), it is possible to visualize all parts of the cavity of the IV ventricle and the rhomboid fossa, as well as the cerebral aqueduct and the most posterior field (area postrema) up to the valve (obex). After completion of the main stage of the operation and performed hemostasis, a 1.5 cm arcuate incision in the dura mater is sutured with a hermetically continuous suture using a 12 mm stabbing needle and a 5-0 absorbable suture material. The bone flap is placed in place and fixed only along the upper edge of the trepanation window, since the lower edge is held by the intact posterior atlantooccipital membrane. For fixation, either 1 craniofix (16 mm in diameter), or 2 titanium microplates and 4 microscrews, or 2 bone sutures are used. Soft tissues are sutured in layers. For suturing the muscles, a continuous suture and a 2-0 absorbable material are used on a 35 mm piercing-cutting needle, and separate non-absorbable silk sutures are used for the aponeurosis. The subcutaneous adipose tissue is sutured with a continuous suture using a 25 mm piercing needle and a 3-0 absorbable suture.

The proposed method of microsurgical access from low-traumatic median suboccipital craniotomy to neoplasms of the posterior cranial fossa, in comparison with currently used approaches, allows:

1. reduce trauma to muscles and soft tissues in the area of the craniovertebral junction;

2. avoid intraoperative complications by preventing damage to venous collectors;

3. to ensure adequate visualization of the cavity of the IV ventricle and the dorsal brainstem, as well as to use the angle of surgical attack that is almost perpendicular to the plane of the rhomboid fossa when manipulating the structures of the brainstem;

4. reduce the risk of developing postoperative liquorrhea and meningitis due to convenient and hermetic suturing of the arcuate incision of the dura mater;

5. preserve the anatomical integrity of the craniovertebral junction and avoid damage to the posterior atlantooccipital membrane.

The consequence of all of the above is the early activation of patients after surgery, the reduction of their stay in the hospital, and the reduction of direct financial costs for treatment.

Clinical observation

Patient T., 32 years old, was admitted to the hospital in a serious condition. The severity of her condition was due to severe neurological symptoms that appeared acutely a month before hospitalization. At the time of admission to the clinic in a neurological status, the patient had severe symptoms of brainstem damage in the form of photoreaction weakness, horizontal gaze paralysis, insufficiency of the facial nerve on the right side with lagophthalmos, severe bulbar disorders, due to which the patient was placed a tracheostomy, and feeding was carried out through nasogastric tube. In addition, the patient had dysfunction of the pelvic organs in the form of a neurogenic bladder, and the patient was also bedridden due to pyramidal tetrasyndrome, more pronounced on the left (plegia), less on the right (decreased strength up to 3 points). The score on the Karnofsky scale was 40 points.

According to MRI data, a large hemorrhage in the right half of the brain bridge was visualized due to a rupture of micromalformation of the brain stem (Fig. 6).

The operation was performed with the patient in the supine position. After standard anesthetic preparation, fixation of the patient's head in a Mayfield bracket and its placement on the operating table, a linear vertical incision of the skin and soft tissues of the cervical-occipital region 6 cm long was made, which began 0.5 cm below the external occipital protrusion and continued down to the level of the spinous process second cervical vertebra. The preparation of soft tissues and their retraction with the help of retractors was performed. The burr hole was set 2.5 cm from the edge of the foramen magnum in the midline. Resection of the remnants of the internal occipital crest was performed using pistol bone nippers. Using a craniotomy, an asymmetric (larger on the access side, to the right of the midline) osteoplastic trepanation was performed, including the posterior half-ring of the foramen magnum. The formed bone flap measuring 2.5 by 2 cm on the preserved posterior atlantooccipital membrane was retracted in the caudal direction and fixed in the surgical wound. The tense dura mater was incised with a 1.5 cm arcuate incision with its base facing the occipital sinus, which was not transected. The arachnoid membrane of the upper sections of the large occipital cistern was dissected. After the cerebrospinal fluid was removed, the tension of the medulla decreased, which made it possible to visualize the landmarks - the inferior vein of the worm, the posterior tonsil vein and the place where the telelolotonsillar segment of the posterior inferior cerebellar artery passes into its cortical segment - to start one-sided preparation of the gap between the uvula of the worm and the right tonsil of the cerebellum from top to bottom and medially up to the hole of Mogendie. After the gap was dissected, the vascular lining of the roof of the fourth ventricle was visualized, which was widely dissected, preserving the branches of the posterior inferior cerebellar artery supplying the choroid plexus. The right half of the rhomboid fossa was exposed in the projection of the fovea superior, colliculus facialis, eminentia medialis and striae medullares. On the surface of the altered fundus of the IV ventricle, a subependymal network of pathological vessels was traced. After mapping and determining the location of the nuclei of the facial and glossopharyngeal nerve, the medulla was diluted 1.0 cm above the striae medullares on the right. A cavity of chronic hematoma containing old, partially lysed blood was opened directly under the ependyma. After the content of the hematoma was removed, its capsule was mobilized from the surrounding medulla, divided into fragments and removed. When mapping the rhomboid fossa after removal of the hematoma, a clear response was obtained from the caudal group of nerves on the left. Hemostasis. A 1.5 cm arcuate incision in the dura mater was sutured with a hermetically continuous suture using a 12 mm stabbing needle and a 5-0 absorbable suture. The bone flap was placed in place and fixed with 2 bone sutures along the upper edge of the trepanation. Soft tissues are sutured in layers.

After the operation, the patient's condition improved significantly. Swallowing disorders regressed, which made it possible to remove the tracheostomy and the probe and transfer the patient to oral feeding. Increased strength and range of motion in the limbs. The patient began to sit down in bed, with support to move within the ward. Assessment of the patient's condition on the Karnofsky scale at the time of discharge - 60 points

According to the control CT scan against the background of postoperative changes in the remnants of the hematoma or signs of re-hemorrhage was not detected (Fig. 7).

The surgical wound healed by primary intention. Liquorrhea or accumulation of liquor in the soft tissues of the neck was not observed. The sutures were removed on the 7th day after the operation.

The patient was discharged from the hospital on the 9th day after the operation to continue rehabilitation and rehabilitation therapy.

Sources of information taken into account

[1] M. G. Yasargil, "Microneurosurgery, IVB, pp. 63-64," Thieme, New York, 1996.

[2] R. R. Pemeczky A, "Keyhole Approaches in Neurosurgery.," New York Springer Wien, 2008.

[3] K. K. Gnanalingham, J. Lafuente, D. Thompson, W. Harkness, and R. Hayward, "Surgical procedures for posterior fossa tumors in children: does craniotomy lead to fewer complications than craniectomy?," J. Neurosurg ., vol. 97, no. 4, pp. 821-826, Oct. 2002, doi: 10.3171/jns.2002.97.4.0821.

[4] S.N. Zaheer and M. Wood, "Experiences with the Telovelar Approach to Fourth Ventricular Tumors in Children," Pediatr. Neurosurg., vol. 46, no. 5, pp. 340-343, 2010, doi: 10.1159/000321539.

[5] S. D. Ferguson et ah, "The surgical treatment of tumors of the fourth ventricle: a single-institution experience," J. Neurosurg., vol. 128, no. 2, pp. 339-351, Feb. 2018, doi: 10.3171/2016.11.JNS161167.

[6] B.J. Rajesh, B.R. M. Rao, G. Menon, M. Abraham, H.V. Easwer, and S. Nair, "Telovelar approach: technical issues for large fourth ventricle tumors," Child's Nerv. Syst., vol. 23, no. 5, pp.555-558, Apr. 2007, doi: 10.1007/s00381-006-0295-0.

[7] S. Han, Z. Wang, Y. Wang, and A. Wu, "Transcerebellomedullary fissure approach to lesions of the fourth ventricle: less is more?," Acta Neurochir. (Wien), vol. 155, no. 6, pp.1011-1016, Jun. 2013, doi: 10.1007/s00701-013-1689-x.

[8] B. QIU et ah, "Microsurgical management of pediatric ependymomas of the fourth ventricle via the trans-cerebellomedullary fissure approach: A review of 26 cases," Oncol. Lett, vol. 11, no. 6, pp. 4099-4106, Jun. 2016, doi: 10.3892/ol.2016.4507.

[9] R. R. A. Perneczky, "Suboccipital approach," in Keyhole Approaches in Neurosurgery Volume 1: Concept and Surgical Technique, Wien, New York: Springer, 2008, p.184.

[10] M.E.S. Charles Teo, Principles and Practice of Keyhole Brain Surgery. Thieme, 2015.

[11] D. Pitskhelauri et al., "Burr Hole Microsurgery for Intracranial Tumors and Mesial Temporal Lobe Epilepsy: Results of 200 Consecutive Operations," World Neurosurg., vol. 126, pp.e1257-e1267, Jun. 2019, doi: 10.1016/j.wneu.2019.02.239.

[12] M. V. Corniola and T. R. Meling, "How I do it: minimally invasive resection of a sub-ependymoma of the fourth ventricle," Acta Neurochir. (Wien), 2020, doi: 10.1007/s00701-020-04601-5.

[13] M. Bergsneider, "Endoscopic removal of cysticercal cysts within the fourth ventricle: technique and results.," Neurosurg. Focus, vol. 6, no. 4, p.e8, Apr. 1999, [Online]. Available: http://www.ncbi.nlm.nih.gov/pubmed/16681362.

[14] R. Austerman, J. Lucas, A. Kammen, and G. Zada, "Endoscopic-Assisted Median Aperture Approach for Resection of Fourth Ventricular Tumor and Confirmation of Patency of Cerebral Aqueduct Using an Adjustable-Angle Endoscope: Technical Case Report ., Oper. neurosurgery. (Hagerstown, Md.), vol. 13, no. 2, pp.293-296, 2017, doi: 10.1093/ons/opw007.

Blueprints

In FIG. 1 shows the position of the patient on the operating table lying on his stomach, the head is fixed in the Mayfield bracket in the midline, the neck is bent, the chin is brought to the sternum.

In FIG. 2 shows a skin incision 6 cm long.

In FIG. 3 shows a craniotomy. A - scheme; B - intraoperative photo: 1 - bone flap; 2 - posterior atlantooccipital membrane.

In FIG. 4 shows an arcuate section through the dura mater. A - scheme; B - intraoperative photo.

In FIG. 5 shows the dissection of the gap between the uvula of the vermis and the cerebellar tonsil: A - diagram; B, C, D, E - intraoperative photos; 1 - amygdala of the cerebellum; 2 - tongue of the cerebellar vermis; 3 - retrotonsillar vein; 4 - televelotonsillar segment of the posterior inferior cerebellar artery; 5 - vascular lining of the roof of the IV ventricle; 6 - branches of the posterior inferior cerebellar artery, leading to the blood supply to the choroid plexus; 7 - bottom of the rhomboid fossa with dilated subependymal vessels.

In FIG. 6 shows MRI before surgery: A - axial view, T1 mode; B - sagittal projection, T1 mode with contrast enhancement: a ring-shaped increase in the signal in the right half of the pons of the brain, which does not accumulate a contrast agent.

In FIG. Figure 7 shows Helical SCT on the first day after surgery: A - axial view; B - 3D-SCT reconstruction: 1 - surgical passage in the gap between the uvula of the worm and the cerebellar tonsil on the right; 2 - cavity of the removed hematoma; 3 - bone flap.

Claims (1)

A method of microsurgical access from low-traumatic median suboccipital craniotomy to neoplasms of the posterior cranial fossa, performed by incision of the soft tissues of the cervical-occipital region, trepanation of the occipital bone, characterized in that a linear vertical incision of the skin and soft tissues of the cervical-occipital region 6 cm long is performed, which begins 0.5 cm below the external occipital protrusion and continues down to the level of the spinous process of the second cervical vertebra, after preparation and retraction of the soft tissues, an asymmetric osteoplastic trepanation is performed on the side where the gap between the uvula and the tonsil of the cerebellum will be further prepared, from one of the burr hole, installed along the midline 2.5 cm from the edge of the foramen magnum, the formed bone flap measuring 2.5 by 2 cm, including the posterior semicircle of the foramen magnum, is left on the intact posterior atlantooccipital membrane and retraction yat in the caudal direction, the dura mater is dissected with an arcuate incision 1.5 cm long with the base facing the occipital sinus, which does not intersect, one-sided preparation of the gap between the uvula of the vermis and the tonsil of the cerebellum is performed from top to bottom and medially to the level of the foramen of Mogendie, focusing on the inferior vein vermis, the posterior tonsil vein and the junction of the telelotonsillar segment of the posterior inferior cerebellar artery into its cortical segment.

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