[Endoscopic transnasal resection of clival meningiomas]. / Rezul'taty endoskopicheskogo transnazal'nogo udaleniya meningiom oblasti skata.

BACKGROUND: Surgical treatment of ventral and ventrolateral meningiomas of posterior cranial fossa is difficult in modern neurosurgery. This is due to peculiarities of approach to these areas and concentration of critical structures (cranial nerves and great vessels). Currently, endoscopic transnasal approach to these meningiomas allows partial, and in some cases, total resection. However, this technique is not widespread. OBJECTIVE: To analyze the world literature data on postoperative outcomes in patients with clival and petroclival meningiomas after endoscopic transnasal resection. MATERIAL AND METHODS: We analyzed 22 articles representing treatment of 61 patients with clival and petroclival meningiomas. RESULTS: Total or near-total resection was achieved in 22.9% of cases, subtotal resection - 40.9%, partial resection - 26.2% (data were not provided in other cases). Even partial and subtotal resection leads to significant regression of symptoms. CONCLUSION: Endoscopic transnasal surgery is a full-fledged alternative to transcranial approaches in surgical treatment of clival meningiomas. It is also an additional option for patients with petroclival meningiomas after ineffective transcranial approaches. Transnasal tumor shrinkage and devascularization lead to brainstem decompression, regression of hydrocephalus and baseline clinical symptoms.

[Chordoid gliomas of the third ventricle]. / Opyt lecheniya khordoidnykh gliom III zheludochka.

BACKGROUND: Chordoid glioma is a rare slow-growing tumor of the central nervous system. Available world experience includes no more than 200 cases (lesion of the third ventricle in absolute majority of cases). Recognition and treatment of chordoid glioma are currently difficult problems due to small incidence of this disease. OBJECTIVE: To describe clinical manifestations and surgical treatment of chordoid glioma of the third ventricle considering literature data and own experience. MATERIAL AND METHODS: There were 12 patients (6 men and 6 women) with chordoid glioma between 2004 and 2023 (10 patients with lesion of the third ventricle, 1 - lateral ventricle, 1 - pineal region). Only patients with tumors of the third ventricle were analyzed. RESULTS: Total and subtotal resection was performed in 1 and 3 cases, respectively. Five patients underwent partial resection, 1 patient underwent biopsy. The follow-up data were available in 7 out of 10 patients (mean 25 months). Radiotherapy was performed in 4 patients (continued tumor growth in 2 cases). One patient died. CONCLUSION: Chordoid glioma is a benign tumor predominantly localized in the third ventricle. Preoperative MRI and CT in some cases make it possible to suspect chordoid glioma and differentiate this tumor from craniopharyngioma, meningioma and pituitary adenoma by such signs as isointense signal in T1WI, hyper- or isointense signal in T2WI, homogeneous contrast enhancement and edema of basal ganglia in T2 FLAIR images. The only effective treatment for chordoid glioma is surgery. Total resection is often impossible or extremely dangerous due to location of tumor, large size and invasion of the third ventricle. Postoperative mental disorders and diabetes insipidus, including severe hypernatremia, are common that requires mandatory monitoring of water and electrolyte balance.

[Predictors of postoperative remission of acromegaly. (Experience of the Burdenko Neurosurgical Center)]. / Prediktory posleoperatsionnoi remissii akromegalii. (Opyt FGAU «NMITs neirokhirurgii im. akad. N.N. Burdenko¼).

BACKGROUND: Treatment of acromegaly is still an unresolved problem. Overall postoperative remission rate ranges from 34 to 85%. These values are better for microadenomas (75-90%) and worse for macroadenomas (45-70%). Identification of predictors of acromegaly remission after surgical treatment is an urgent objective to improve the quality of medical care for these patients. OBJECTIVE: To analyze postoperative freedom from acromegaly and predictors of remission. MATERIAL AND METHODS: A retrospective single-center study included 227 patients with acromegaly who underwent resection of pituitary adenoma between August 2018 and August 2021. RESULTS: Remission (normalization of serum IGF-1) was achieved in 65 (55%) patients. Growth hormone and IGF-1 index decreased after surgery in all patients. Mean preoperative serum growth hormone was 12.45 [6.88, 29.85] ng/ml, early postoperative concentration - 1.54 [0.80, 3.38] ng/ml, in delayed period - 1.15 [0.57, 3.80] ng/ml. Mean IGF-1 index was 2.18 [1.69, 2.71], 1.47 [0.99, 1.90] and 0.99 [0.74, 1.43], respectively. CONCLUSION: Significant predictors of acromegaly remission after neurosurgical treatment were age, preoperative level of growth hormone, tumor size and location, growth hormone and IGF-1 index in early postoperative period and residual tumor after surgery. Multivariate analysis revealed a significant association of acromegaly remission with small tumor size, low postoperative level of growth hormone and no residual tumor within 3-6 month after surgery.

[Endoscopic transnasal resection of clival meningiomas]. / Endoskopicheskoe transnazal'noe udalenie meningiom skata.

Treatment of clival meningiomas is still one of the unresolved issues in modern neurosurgery. There are several treatment strategies. These ones include various combinations of follow-up, surgical CSF drainage, tumor resection and radiotherapy. OBJECTIVE: To assess postoperative outcomes in patients with clival meningiomas. MATERIAL AND METHODS: We analyzed 18 patients with large or giant clival meningiomas. RESULTS: We assessed extent of resection using the scale by G. Frank and E. Pasquini (2002): total resection - 95-100%, subtotal - 80-95%, partial - 50-80%, extended biopsy - <50% of tumor. Total resection was achieved in 1 patient (5.5%), subtotal - 5 (27.8%), partial - 12 (66.7%). At the same time, brainstem decompression and regression of hydrocephalus were observed in all cases. Fourteen patients were followed-up. Median follow-up was 8.5 months. Seventeen patients underwent radiotherapy due to predominant partial and subtotal resection. Total focal dose ranged from 50 to 57 Gy in standard fractionation mode. None patient had residual tumor enlargement throughout the follow-up period. There were no lethal outcomes. CONCLUSION: Endoscopic transnasal access to clival meningiomas in appropriate anatomical features of tumor and surrounding structures is a full-fledged alternative to transcranial treatment in these patients. This approach provides total resection and brainstem decompression. These facts increase life expectancy without deterioration of the quality of life.

[Minimally invasive surgery for invaginated CII odontoid process]. / Miniinvazivnaya khirurgiya invaginirovannogo zubovidnogo otrostka CII pozvonka.

Odontoidectomy is indicated for anterior compression of the brainstem by invaginated odontoid process. This procedure can currently be performed via transoral microsurgical and transnasal endoscopic access. OBJECTIVE: To analyze the results of endoscopic transnasal odontoidectomy. MATERIAL AND METHODS: We assessed treatment outcomes in 10 patients with anterior compression of the brainstem by invaginated odontoid process. All patients underwent endoscopic transnasal odontoidectomy. RESULTS: Brainstem decompression was achieved in all cases. CONCLUSION: Currently, endoscopic transnasal approach is gradually replacing the transoral one in some patients requiring anterior odontoidectomy. Analysis of literature data reflects the development of this technique taking into account various features of surgical treatment including optimization of dimensions of surgical field, attempts to perform C1-sparing surgeries and analysis of sufficient size of trepanation. Nasopalatine and nasoclival lines are used to select optimal access. Nevertheless, the choice of access depends on equipment of the hospital and surgical experience in most cases.

[Adipsic diabetes insipidus after transsphenoidal surgery for suprasellar intraventricular].

Presented case demonstrates a rare diencephalic pathology - adipsic diabetes insipidus (ADI) with severe hypernatremia in a 58-year-old woman after ttranssphenoidal removal of stalk intraventricular craniopharyngioma. ADI was diagnosed because of hypernatremia (150-155 mmol/L), polyuria (up to 4 liters per day) and absence of thirst. Normalization of water-electrolyte balance occurred on the background of desmopressin therapy and sufficient hydration in postoperative period. After release from the hospital, the patient independently stopped desmopressin therapy and did not consume an adequate amount of fluid of the background of polyuria. This led to severe hypernatremia (155-160 mmol/L) and rough mental disorders.Patients with ADI need closely monitoring of medical condition and water-electrolyte parameters, appointment of fixed doses of desmopressin and adequate hydration.

[«Burr hole¼ microsurgery for vestibular schwannoma]. / «Burr hole¼ mikrokhirurgiya vestibulyarnykh shvannom.

OBJECTIVE: To evaluate the efficacy and safety of minimally invasive «burr hole¼ microsurgery for vestibular schwannoma. MATERIAL AND METHODS: A retrospective analysis of postoperative outcomes in 50 consecutive patients with vestibular schwannoma was performed. All patients underwent burr hole microsurgery between 2016 and 2020. RESULTS: All patients satisfactorily tolerated surgical treatment. Total resection was carried out in 21 (42%) cases, almost total resection - in 21 (42%) patients (>95% of baseline volume). Subtotal resection was performed in 8 (16%) cases. Mean surgery time was 132 min (range 60-340). Postoperative deterioration of facial nerve function occurred in 20 (40%) patients. Severe dysfunction (House-Brackmann grade V-VI) was observed only in three patients. Other 17 patients had moderate dysfunction of the facial nerve (House-Brackmann grade III-IV). Useful hearing was preserved in 6 (50%) out of 12 patients with preoperative useful hearing. CONCLUSION: Minimally invasive burr hole microsurgery is an effective method for vestibular schwannoma. Moreover, the proposed technique reduces surgery time due to simpler craniotomy and wound closure.

[Endoscopic transnasal approach in surgical treatment of petrous temporal bone cholesteatoma extending towards the clivus. Three clinical observations and literature review]. / Endoskopicheskii transnazal'nyi dostup v khirurgicheskom lechenii kholesteatom piramidy visochnoi kosti, rasprostranyayushchikhsya v oblast' skata. Tri klinicheskikh nablyudeniya i obzor literatury.

Petrous temporal bone Cholesteatoma is widely described in the literature and accounts for up to 9% of all neoplasms of this localization. These cholesteatomas rarely spread towards the clivus. Isolated clival cholesteatomas are described only as single cases. There is currently no consensus on the choice of surgical approach for resection of similar neoplasms. OBJECTIVE: To demonstrate the possibilities of endoscopic transnasal approach in surgery for clival and petrous cholesteatoma. MATERIAL AND METHODS: This article presents 3 clinical cases: 2 patients with apical cholesteatoma of petrous part of temporal bone extending to the clivus and 1 patient with massive petrous temporal bone cholesteatoma extending towards the clivus according to the classification of Sanna M. All patients underwent endoscopic transnasal surgery. RESULTS AND CONCLUSION: In our opinion, endoscopic transnasal approach is optimal for resection of similar neoplasms. Total and subtotal resection was performed in 2 and 1 case, respectively. However, there are certain limitations of this approach in accessing the most lateral parts of the neoplasm. Nevertheless, endoscopic transnasal approach ensures resection of petrous temporal bone cholesteatoma extending to the clivus without the risk of damage to acoustic-facial cranial nerves. It is especially significant in patients without their baseline dysfunction.

[Modern aspects of surgery for cushing's disease]. / Sovremennye aspekty khirurgicheskogo lecheniya bolezni Itsenko­Kushinga.

Cushing's disease is a severe neuroendocrine disorder caused by chronic hypersecretion of ACTH by pituitary adenoma (corticotropinoma). Surgical resection is a gold standard for this disease resulting stable remission in about 65-95% of cases. Despite benign nature of corticotropinoma, recurrence rate is still higher (25-35%) even in specialized neurosurgical centers. Modifications in surgical strategy can prolong recurrence-free period.

[Combination of pituitary adenomas and intracranial aneurysms]. / Sochetanie adenom gipofiza i intrakranial'nykh anevrizm.

The combination of intracranial tumors and asymptomatic brain aneurysms is an urgent problem, since it can significantly affect surgical intervention. Aneurysms are common in patients with meningioma, glioma and pituitary adenoma. According to certain authors, combination of aneurysms with pituitary adenomas is 7 times more common than with other tumors. In these cases, a comprehensive examination of the patient and decision-making on surgical strategy are required. This review is devoted to epidemiology, diagnosis and treatment of patients with a combination of pituitary adenomas and intracranial aneurysms detected intraoperatively or at the preoperative stage. The manuscript is illustrated by cases observed at the Burdenko Neurosurgery Center.

[Anatomy of anterior craniovertebral junction in endoscopic transnasal approach]. / Anatomiya perednikh otdelov kraniovertebral'nogo sochleneniya pri endoskopicheskom transnazal'nom dostupe.

Modern achievements in endoscopic technologies ensure extending the indications for endoscopic transnasal approach in skull base surgery. Knowledge on topographic anatomy of craniovertebral junction is a prerequisite for surgical interventions in this area. Transnasal endoscopic surgery of craniovertebral junction is a relatively new field. Therefore, this manuscript and similar anatomical studies are extremely important for neurosurgeons.

[Transcranial microsurgical decompression of the optic canal in surgical treatment of meningiomas of the sellar region]. / Transkranial'naya mikrokhirurgicheskaya dekompressiya kanala zritel'nogo nerva v khirurgii meningiom khiazmal'no-sellyarnoi oblasti.

RATIONALE: When removing the meningiomas of the sellar region, there is always a risk of visual impairment for various reasons, in particular, as a result of traction damage to the optic nerve. Decompression of the optic canal increases nerve mobility during tumor manipulation. In cases of meningioma growing into the canal, its decompression often seems necessary. AIM: Evaluation of the effectiveness and risks of performing decompression of the optic canal. MATERIALS AND METHODS: The study included patients with meningiomas of the parasellar location, who underwent surgical treatment at the Burdenko Neurosurgical Center for the period from 2001 to 2017. They were divided into two groups - main and control. The main group consisted of 129 patients who underwent decompression of the optic nerve canals when the tumor was removed. The tumor matrix in this group was most often located in the region of the tuberum sellae, supradiaphragmally, in the region of the anterior clinoid process and the optic canal. In 31 cases, decompression was bilateral - during one operation and using one access in 27 patients; in 4 cases, the decompression of the second canal was delayed for 1.5-3 months after the first operation. 160 decompressions were performed by the intradural and 7 - by extradural methods. During intradural decompression, the roof of the optic canal was resected, and during extradural decompression, the lateral wall of the canal was trephined. The control group consisted of 308 patients who did not undergo canal decompression when the tumor was removed. It included meningiomas with a predominant location of the matrix in the area of the tuberclum and diaphragm of the sella. Tumors in both groups were removed according to the same principles (matrix coagulation, mainly the gradual removal of the tumor, the use of ultrasonic aspirator, a situational decision on the radicality of the operation, etc.). The main difference between operations in these two groups was only canal related algorithms (with or without its trepanation), as well as the probable prevalence of significant lateral tumor growth in cases with canal trepanation. Visual functions in the «primary¼ group were evaluated before and after operations with trepanation of the canal depending on various factors - the initial state of vision and the radicality of the tumor excision, including removal from the canal. The differences in the postoperative dynamics of vision in the main and control groups were studied. The primary data processing was carried out using the program MSExcel. Secondary statistical processing was carried out using the program Statistica. To assess the statistical significance of differences in the results obtained in the compared patient groups, the Chi-square test was used, and in the case of small groups - the exact Fisher test was applied. RESULTS: In the main group postoperative vision improvement of varying degrees on the side of trepanation was registered in 36.9% (59 out of 160) cases, no vision changes were found in 36.9% (59 out of 160), and in 26,2% (42 out of 160) the eyesight deteriorated. If preserving vision is attributed to a satisfactory result, then in general the results of these operations should be considered good. A comparative study of the results of removal of meningiomas with trepanation of the canals (main group) or without it (control group) was carried out among patients with the most critical vision situation (visual acuity 0.1 and below, up to only light perception). These groups are comparable in the number of observations - 62 and 73 respectively. The predominance of cases with improved vision in the main group compared with the control group (50.0% versus 38.36%) and a lower incidence of vision impairment (22.58% versus 34.25%) were found. However, the revealed differences are statistically unreliable and make it possible for us to talk only about the trend. The complications associated with trepanation of the canal include mechanical damage to the nerve by the drill. In our series of observations, there was only 1 case of abrasion of the nerve surface with the burr, which did not lead to a significant visual impairment. With the intradural method of trepanation in the area of the medial wall of the canal, the sphenoid sinus may open (in our series, in 34 cases out of 160 trepanations). Immediately closure of these defects was performed by various auto- and allomaterials in various combinations (pericranium, fascia, muscle fragment, hemostatic materials, and fibrin-thrombin glue). A true complication - CSF rhinorrhea liquorrhea developed in only one case, which required transnasal plastic surgery of the CSF fistula using a mucoperiostal flap. CONCLUSIONS: 1. Trepanation of the optic canal in cases of meningiomas of parasellar localization is a relatively safe procedure in the hands of a trained neurosurgeon and does not worsen the results of operations compared with the excision of the same tumors without trepanation of the canal. 2. The literature data and the results of our study make it possible to consider the decompression of the optic canal as an optional, but in many cases, useful option that facilitates the transcranial removal of some meningiomas of the sellar region.

[Primary sellar neuroblastoma (clinical case and literature review)]. / Pervichnaya sellyarnaya neiroblastoma. Klinicheskoe nablyudenie i obzor literatury.

Neuroblastoma is a malignancy developing from the embryonic neuroblasts of sympathetic nervous system. Primary sellar neuroblastomas are extremely rare (there are currently only 11 case reports in the literature). Possible development of neuroblastoma in sellar region expands differential diagnosis of local processes due to inclusion of neuroblastoma into the spectrum of suspected tumors. We report a literature review and description of a patient with primary sellar neuroblastoma.

[Pituitary microadenomas - current diagnostic and treatment methods]. / Mikroadenomy gipofiza: sovremennoe sostoyanie metodov diagnostiki i lecheniya.

According to previously accepted criteria, pituitary microadenoma is characterized by a diameter of less than 10 mm. Improvement and widespread use of MRI are accompanied by increased incidence of diagnosis of these neoplasms. Pituitary microadenomas is an extremely heterogeneous group of tumors with different biological behavior, endocrine secretion and clinical symptoms despite the common MR characteristics. Treatment is mainly determined by endocrine secretion. Endocrine-active microadenoma requires medication (in case of microprolactinoma) and surgical treatment (in case of microsomatotropinoma and ACTH-releasing tumor). Follow-up is advisable for endocrine-inactive microadenoma (microincidentaloma). Modern data on the incidence, clinical and endocrine features, diagnosis and treatment of various pituitary microadenomas are discussed in the article.

[Use of chemotherapy in the treatment of aggresive pituitary adenomas]. / Khimioterapiia v lechenii agressivnykh adenom gipofiza.

AIM: To clarify the concept of 'aggressive pituitary adenoma' using analysis of the current concepts, as well as to determine the optimal treatment algorithm for this disease and the place of chemotherapy in this treatment. Pituitary adenomas comprise from 10 to 15% of intracranial neoplasms. Despite the fact that pituitary adenomas are benign neoplasms, in 25-55% of cases they demonstrate invasive growth, growing into the surrounding structures (sphenoid sinus, cavernous sinus, etc.). Due to the lack of a standard definition of aggressive pituitary adenomas (due to the lack of clear criteria for this disease), there are no studies in the literature reporting optimal treatment for this group of patients, except for several publications describing the use of Temozolomide as palliative therapy.

[Treatment of primary craniofacial (sinonasal) malignant tumors affecting the anterior and middle skull base]. / Lechenie pervichnykh kraniofatsial'nykh (sinonazal'nykh) zlokachestvennykh opukholei, porazhaiushchikh perednie i srednie otdely osnovaniia cherepa.

Sinonasal malignant tumors are characterized by high histological variability and complexity of the differential diagnosis. Currently, there are classifications of these tumors, which are based on their localization and involvement of various anatomical structures. However, generally accepted algorithms for treatment of this pathology have not yet been developed. This review describes the most important algorithms for treatment of the most common histological variants of sinonasal malignant tumors: squamous cell carcinoma, adenocarcinoma, sinonasal undifferentiated carcinoma, esthesioneuroblastoma, adenoid cystic cancer, and sinonasal adenocarcinoma. The main problems in choosing the approach for treating these tumors are the lack of generally accepted resectability criteria and contradictions between oncological and neurosurgical indications for surgical treatment. Further research is needed to study the role of radiosensitizers and radioprotectors in comprehensive treatment of sinonasal malignant tumors.

[Transsphenoidal surgery of suprasellar meningiomas - is there a future for the technique?] / Transsfenoidal'naia khirurgiia supraselliarnykh meningiom - est' li budushchee u metodiki?

Surgery of suprasellar meningiomas is a challenge and associated with a high risk of injury to the vascular-neural structures lying along the approach and surrounding the tumor. Currently, many foreign clinics and our Center have introduced a technique for resection of suprasellar meningiomas through the anterior extended transsphenoidal endoscopic endonasal approach. OBJECTIVE: The study objective was to evaluate the role of extended transsphenoidal endoscopic endonasal approaches in surgery of suprasellar meningiomas. MATERIAL AND METHODS: The present study is a retrospective analysis of surgical treatment outcomes in 45 patients (11 males and 34 females aged 23 to 70 years (median, 50 years) with suprasellar meningiomas who underwent surgery for skull base tumors using the anterior extended transsphenoidal endoscopic endonasal approach in the Surgery Department of the Burdenko Neurosurgical Institute in the period from 2009 to 2017. In all cases, surgery was the primary method of treatment. RESULTS: Total tumor resection (the tumor was resected completely together with an infiltrated DM - Simpson 1) was achieved in 77.8% (35/45) of cases; subtotal resection (more than 80% of the tumor was removed) was in 17.8% (8/45) of cases; in 4.4% (2/45) of cases, resection was partial (less than 80% of the tumor was resected). Worsening or development of visual impairments immediately after surgery occurred in 13 (28%) of 45 patients. In 3 of them, vision was completely recovered on conservative treatment by the time of hospital discharge. In 4 patients, vision partially improved by the time of discharge. In 6 patients, vision was not recovered by discharge (in 2 of them, vision partially improved during follow-up). Therefore, by the time of hospital discharge, deterioration in vision occurred in 10 (22%) of 45 patients. In 7 (21.2%) out of 33 patients who had visual impairments before surgery, there was an improvement in vision in the postoperative period. CONCLUSION: Analyzing the findings and generalizing our experience, we may say that, in surgery of suprasellar meningiomas, the anterior extended transsphenoidal endoscopic endonasal approach should be used for relatively small (up to 3 cm), medially located symmetrical tumors that do not involve large vessels. The efficacy of this technique for tumors extending into the optic nerve canals requires additional analysis in a larger series of cases.

[Anterior stabilization of the CI-CIII vertebrae after transoral removal of an aggressive aneurysmal bone cyst of the CII vertebra (a case report and literature review)]. / Peredniaia stabilizatsiia SI-SIII pozvonkov posle transoral'nogo udaleniia agressivnoi anevrizmaticheskoi kisty SII pozvonka (klinicheskoe nabliudenie i obzor literatury).

Treatment of patients with atlantoaxial instability caused by various diseases of the skull base and craniovertebral junction combined with ventral compression of the brainstem is a complex issue that is ambiguously resolved in different ways. We present a case of stepped treatment, the most important component of which was successful transoral removal of an aggressive aneurysmal bone cyst of the CII vertebra with anterior CI-CIII segment stabilization using an individual system, which was performed through the same approach. CLINICAL CASE: A 31-year-old male patient presented with destruction of the CII body and odontoid process affected by an aggressive aneurysmal bone cyst causing disintegration of the CII posterior wall and odontoid process, which clinically manifested by constricted motion and pain in the cervical spine. RESULTS: Three-step surgical treatment was performed. First, we performed a puncture biopsy of the CII body through the submandibular approach as well as posterior occipitospondylodesis with metal instrumentation from the occipital bone level to the CIV vertebra. Two months later, the patient underwent transoral removal of the CII body and odontoid process lesion and anterior CI-CIII segment stabilization using an individual cover metal system through the same approach. Two weeks after the second intervention, the occipitospondylodesis was transformed to a posterior CI-CIII stabilization system. Control CT 8 months after surgery showed the correct position of both stabilization systems. CONCLUSION: The use of individual instrumentation for anterior stabilization of the CI-CIII vertebrae in various diseases of the craniovertebral junction area is an effective and promising technique.

[Extended endoscopic endonasal posterior (transclival) approach to tumors of the clival region and ventral posterior cranial fossa. Part 3. Analysis of surgical treatment outcomes in 127 patients]. / Éndoskopicheskii éndonazal'nyi zadnii rasshirennyi (transklival'nyi) dostup k opukholiam oblasti skata cherepa i ventral'nykh otdelov zadnei cherepnoi iamki. Chast' 3. Analiz rezul'tatov khirurgicheskogo lecheniia 127 patsientov.

Until recently, tumors of the clival region and ventral posterior cranial fossa were considered hard-to-reach and often inoperable via standard transcranial approaches. The introduction of minimally invasive methods combined with the endoscopic technique into neurosurgical practice has enabled removal of hard-to-reach tumors, including midline tumors of the ventral posterior cranial fossa. OBJECTIVE: To improve and introduce the extended endoscopic endonasal posterior (transclival) approach into clinical practice and to analyze the results of its application in surgical treatment of midline skull base tumors extending into the ventral posterior cranial fossa. MATERIAL AND METHODS: During the period from 2008 to the present, we have operated 127 patients with various skull base tumors located in the clival region and ventral posterior cranial fossa (60 males and 67 females); the patients' age was 3 to 74 years. The distribution of tumors by histology was as follows: 96 (75.6%) chordomas, 9 (7.1%) pituitary adenomas, 8 (6.3%) meningiomas, 3 (2.33%) cholesteatomas, 2 (1.6%) craniopharyngiomas, 3 (2.33%) fibrotic dysplasia, and 6 (4.7%) other tumors (giant cell tumor, glioma of the neurohypophysis, osteoma, plasmacytoma, carcinoid tumors, chondroma). The tumor size was as follows: 36 (28.35%) giant (more than 60 mm) tumors, 71 (55.9%) large (35-59 mm) tumors, 19 (14.96%) medium (21-35 mm) tumors, and 1 (0.79%) small (less than 20 mm) tumor. Intraoperative monitoring of the cranial nerves was performed (20 cranial nerves were identified) in 10 cases. RESULTS: The extent of chordoma resection was as follows: total removal - 63 (65.62%) cases, subtotal removal - 23 (23.96%) cases, and partial removal - 10 (10.42%) cases. Pituitary adenomas were resected totally in 6 cases, subtotally in 1 case, and partially in 2 cases. Meningioma was removed subtotally in 4 cases, partially in 3 cases, and less than 50% in 1 case. Other tumors (cholesteatoma, craniopharyngioma, fibrous dysplasia, giant cell tumor, glioma of the neurohypophysis, osteoma, plasmacytoma, carcinoid tumors, chondroma) were removed totally in 7 cases and subtotally in 7 cases. Postoperative cerebrospinal fluid leakage occurred in 9 (7.2%) cases, and meningitis developed in 12 (9.4%) cases. Oculomotor disorders occurred in 17 (13.4%) patients; in 10 of these patients, the disorders regressed within 4 to 38 days after surgery; in 7 patients the oculomotor disorders did not regress. A lethal outcome occurred in 2 (1.57%) cases. CONCLUSION: The extended endoscopic endonasal posterior (transclival) approach, being minimally invasive, enables removal of various midline skull base tumors with/without involvement of the clivus with high radicalness, low risk of postoperative complications, and low lethality. Until recently, these tumors were considered almost inoperable.

Cranial nerve monitoring in endoscopic endonasal surgery of skull base tumors (observing of 23 cases).

BACKGROUND: Preservation of anatomic integrity and function of the cranial nerves during the removal of skull base tumors is one of the most challenging procedures in endoscopic endonasal surgery. It is possible to use intraoperative mapping and identification of the cranial nerves in order to facilitate their preservation.The purpose of this study was to evaluate the effectiveness of intraoperative trigger electromyography in prevention of iatrogenic damage to the cranial nerves. METHODS: Twenty three patients with various skull base tumors (chordomas, neuromas, pituitary adenomas, meningiomas, cholesteatomas) underwent mapping and identification of cranial nerves during tumor removal using the endoscopic endonasal approach in Department of Neurooncology of Federal State Autonomous Institution "N.N. Burdenko National Medical Research Center of Neurosurgery" of the Ministry of Health of the Russian Federation from 2013 to 2018. During the surgical interventions, mapping and identification of the cranial nerves were carried out using electromyography in triggered mode. The effectiveness of the method was evaluated based on a comparison with a control group (41 patients). RESULTS: In the main group of patients, 44 nerves were examined during surgery using triggered electromyography. During the study, the III, V, VI, VII, and XII cranial nerves were identified intraoperatively. Postoperative cranial nerve deficiency was observed in 5 patients in the study group and in 13 patients in the control group. The average length of hospitalization was 9 days. CONCLUSION: We did not receive statistically significant data supporting the fact that intraoperative identification of cranial nerves using trigger electromyography reduces the incidence of postoperative complications in the form of cranial nerve deficits (p = 0.56), but the odds ratio (0.6) suggests a less frequent occurrence of complications in the study group.Based on our experience, the trigger electromyography methodology appears quite promising and requires further research.