[Primary tumors of the brain stem. State of the problem]. / Pervichnye opukholi stvola golovnogo mozga. Sostoyanie problemy.

Primary brainstem gliomas are still poorly studied in neurooncology. This concept includes tumors with different histological and genetic features, as well as variable clinical course and outcomes. Nevertheless, treatment implies radiotherapy without a clear idea of morphological substrate of disease in 80% of cases. Small number of studies and insufficient data on histological and genetic nature of brainstem tumors complicate clear diagnostic and treatment algorithms. This review provides current information regarding primary glial brainstem tumors. Appropriate problems and objectives are highlighted. The purpose of the review is to provide a comprehensive and updated understanding of the current state of brainstem glial tumors and to identify areas requiring further study for improvement of diagnosis and treatment of these diseases. Brainstem tumors are an understudied problem with small amount of data that complicates optimal treatment strategies. Further researches and histological verification are required to develop new methods of therapy, especially for diffuse forms of neoplasms.

[Analysis of intracranial saccular aneurysm wall: neuroimaging and histopathological correlates]. / Issledovanie stenki intrakranial'nykh meshotchatykh anevrizm: neirovizualizatsionnye i gistopatologicheskie korrelyaty.

BACKGROUND: Contrast enhancement of intracranial aneurysm wall during MRI with targeted visualization of vascular wall correlates with previous aneurysm rupture and, according to some data, may be a predictor of further rupture of unruptured aneurysms. OBJECTIVE: To analyze possible causes of aneurysm contrast enhancement considering morphological data of aneurysm walls. MATERIAL AND METHODS: The study included 44 patients with intracranial aneurysms who underwent preoperative MRI between November 2020 and September 2022. Each aneurysm was assessed regarding contrast enhancement pattern. Microsurgical treatment of aneurysm was accompanied by resection of its wall for subsequent histological and immunohistochemical analysis regarding thrombosis, inflammation and neovascularization. Specimens were subjected to histological and immunochemical analysis. Immunohistochemical analysis was valuable to estimate inflammatory markers CD68 and CD3, as well as neurovascularization marker SD31. RESULTS: Aneurysms with contrast-enhanced walls were characterized by higher number of CD3+, CD68+, CD31+ cells and parietal clots. Intensity of contrast enhancement correlated with aneurysm wall abnormalities. CONCLUSION: Contrast enhancement of aneurysm wall can characterize various morphological abnormalities.

[Recovery of consciousness under therapy with benzodiazepines. A case report and literature review]. / Vosstanovlenie yasnogo soznaniya na fone priema benzodiazepinov. Opisanie sluchaya i obzor literatury.

BACKGROUND: Treatment of patients with prolonged and permanent disturbance of consciousness is still an extremely difficult problem. Nowadays, management is based on pathophysiological and molecular mechanisms of impaired consciousness. Several electrophysiological and pharmacological methods were proposed to restore consciousness in appropriate patients. OBJECTIVE: We present recovery of clear consciousness under therapy with phenazepam and literature review devoted to therapy of these disorders. RESULTS AND CONCLUSION: This case confirms available data on drug neuromodulation in complex treatment of patients with prolonged impairment of consciousness and substantiates the need for individual multimodal assessment of structural and functional disorders in prolonged and chronic impairment of consciousness for adequate therapy.

[Magnetic resonance imaging of saccular intracranial aneurysm wall]. / MR-vizualizatsiya sosudistoi stenki meshotchatykh intrakranial'nykh anevrizm.

BACKGROUND: Hemorrhage from intracranial aneurysms is associated with high risk of adverse outcomes. In this regard, surgical treatment of unruptured asymptomatic aneurysms has been actively developed in recent decades. One of the objectives is searching for predictors of aneurysm rupture to clarify the indications for surgery. Non-invasive analysis of vascular wall is actively discussed in last years. OBJECTIVE: To evaluate the possibilities of MRI of ruptured and unruptured intracranial aneurysm walls and determine clinical significance of certain morphological patterns. MATERIAL AND METHODS: The study included 111 patients with 158 ruptured and unruptured saccular aneurysms who underwent MRI according to a special protocol between November 2020 and September 2023. We analyzed each aneurysm regarding features of contrast enhancement and changes in SWAN images. After that, we compared these data with ruptures. RESULTS: Wall of ruptured and unruptured aneurysms can accumulate contrast agent. We found 5 types of contrast enhancement. Thick-layer contrast enhancement was accompanied by 9.6-fold higher risk of aneurysm rupture compared to aneurysms without contrast enhancement. Dark MR signal from intracranial aneurysm wall in SWAN imaging is a significant sign of rupture. CONCLUSION: MRI of the vascular wall is valuable to verify ruptured aneurysms. Unruptured aneurysms can accumulate contrast agent inside the wall, and pattern of accumulation differs from ruptured aneurysms. Morphological analysis is needed to confirm contrast enhancement as a marker of aneurysm rupture.

[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.

[Neurosurgeon training: current problems and modern approaches]. / Obuchenie neirokhirurga: aktual'nye problemy i sovremennye podkhody.

Analysis of historical and modern approaches to teaching neurosurgery by professional communities and public authorities in the United States, the European Union and the Russian Federation makes it possible to develop a modern training program regarding content and duration. High-tech and dynamically developing specialty has acquired several large sub-specializations over the past decades. Each direction requires a long-term training and a special program. Training in neurosurgery in the modern world takes 5-7 years and involves acquisition of clinical and scientific knowledge. Some issues are brought up for discussion by professional community. Solution of these problems will provide an opportunity for international integration of the Russian training program for neurosurgeons. High level of neurosurgery in our country and a single educational space with the European community will allow exchanging students, adopting foreign experience and sharing our own experience.

[Surgical treatment of hemispheric and subcortical gliomas adjacent to corticospinal tract in children using MR tractography and intraoperative electrophysiological monitoring]. / Opyt khirurgicheskogo lecheniya gliom bol'shikh polusharii i podkorkovykh struktur golovnogo mozga, prilegayushchikh k kortikospinal'nomu traktu, u detei s ispol'zovaniem MR-traktografii i intraoperatsionnogo elektrofiziologicheskogo monitoringa.

Difficult total resection of supratentorial gliomas adjacent to the corticospinal tract (CST) is due to the high risk of its injury and disability of patients. The main methods for preventing intraoperative CST damage are preoperative MR tractography and intraoperative electrophysiological monitoring. The problem of total resection of gliomas adjacent to the CST with preservation of high functional status is difficult due to immaturity and plasticity of brain structures in children. Moreover, the advantages of MR tractography combined with intraoperative monitoring have not been described. The authors present surgical treatment of supratentorial gliomas adjacent to the CST at different anatomical levels. Patients underwent preoperative and postoperative MR tractography and intraoperative electrophysiological monitoring. MR tractography provided preoperative data on CST lesion. Intraoperative monitoring made it possible to identify and preserve CST in the depth of surgical wound. MR tractography and intraoperative electrophysiological monitoring increase resection quality in patients with hemispheric and subcortical gliomas without postoperative functional deterioration.

[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.

[Central neurocytomas: long-term treatment outcomes]. / Tsentral'nye neirotsitomy golovnogo mozga: otdalennye rezul'taty lecheniya.

Central neurocytoma is a rare benign brain tumor. These tumors may be giant and accompanied by compression of ventricular system and surrounding structures. Modern treatment of brain neurocytoma includes extended resection and restoration of normal CSF circulation. Surgical treatment does not often lead to total resection of these tumors. Redo resection was preferred in patients with tumor progression for a long time. In the last decade, various authors report stereotactic irradiation for continued tumor growth to ensure local growth control. This study was aimed at evaluation of postoperative outcomes in patients with brain neurocytomas, as well as treatment of tumor progression in long-term period. OBJECTIVE: To analyze recurrence-free survival in patients with brain neurocytomas, risk factors of recurrence-free survival, effectiveness of various treatments for tumor progression and delayed complications. MATERIAL AND METHODS: Long-term postoperative follow-up data of patients with brain neurocytomas are reported in the manuscript. We analyzed recurrence-free survival and risk factors of recurrence-free survival, treatment outcomes in patients with progression of brain neurocytomas, long-term complications and their prevention. RESULTS: Follow-up included 84 out of 115 patients with brain neurocytoma after surgical treatment in 2008-2017. Follow-up period ranged from 2 to 10 years (mean 6 years) after resection. Most patients had regression of neurological symptoms after surgery. Continued tumor growth within 12-96 months after surgery occurred in 26 (30.19%) out of 84 patients (19 cases after partial resection and 7 cases after total resection according to MRI data). Two-year recurrence-free survival was 94%, 5-year survival - 83%. Risk factors of continued tumor growth were resection quality and Ki-67 index. Redo resection was performed in 7 cases. Eleven patients underwent stereotactic irradiation for tumor progression. Indications for stereotactic irradiation of central neurocytoma are MR data on continued growth of lateral ventricle tumor without signs of ICH and CSF flow impairment. There were no cases of hemorrhage inside the residual tumor and CSF flow impairment in early postoperative period after redo resection. In all cases (n=11), stereotactic irradiation (mean follow-up 2.5 years) ensured satisfactory control of tumor growth with reduction of the neoplasm in 4 cases and no tumor growth in 7 cases. CONCLUSION: Resection of central neurocytoma ensures long-term recurrence-free period. The main causes of tumor recurrence are partial resection and high proliferative activity (Ki-67 index over 5%). Redo resection is advisable for tumor progression followed by CSF flow impairment. In case of continued growth of neurocytoma without signs of intracranial hypertension, stereotactic irradiation with various fractionation modes ensures effective and safe control of tumor growth.

[Stereotactic irradiation in the complex treatment of patients with intracranial pilocytic astrocytoma]. / Stereotaksicheskoe obluchenie v kompleksnom lechenii patsientov s intrakranial'nymi piloidnymi astrotsitomami.

Complex management of patients with intracranial pilocytic astrocytoma (PA) consists of surgical treatment, drug therapy (mainly in young children) and radiotherapy. For many years, radiotherapy (RT) has been a standard for residual tumors, recurrence or continued growth of PA. Currently, stereotactic radiosurgery and radiotherapy are preferred for PA, because these procedures are characterized by high conformity and selectivity, precise irradiation of tumor with minimal damage to surrounding intact tissues. Stereotaxic approach is very important since PAs are localized near functionally significant and radiosensitive brain structures in most cases. There is significant experience of single-center studies devoted to radiotherapy of patients with PA at the Department of Neuroradiosurgery of the Burdenko Neurosurgery Center. In this research, the authors analyzed the results of stereotactic irradiation of 430 patients with PA for the period from 2005 to 2018.

[Surgical treatment of drug-resistant epilepsy following hippocampal sclerosis]. / Khirurgicheskoe lechenie farmakorezistentnoi epilepsii pri skleroze gippokampa.

Surgery is an effective approach for drug-resistant temporal lobe epilepsy following hippocampal sclerosis. There is still no clear and unanimous opinion about advantages and disadvantages of certain surgical technique. MATERIAL AND METHODS: There were 103 surgical interventions in 101 patients. Females prevailed (1.45:1). Age of patients ranged from 16 to 56 years (median 28). Anteromedial temporal lobectomy and selective amygdaloghippocampectomy were performed in 49 (47.6%) and 54 (52.4%) patients, respectively. In the latter group, 30 patients were operated via a 14-mm burr hole-subtemporal approach. Postoperative outcomes were assessed using the Engel grading system. The follow-up period ranged from 2 to 8 years (median 4 years). RESULTS: By the 2nd year, Engel class I was observed in 74 (72%) patients, Engel II, III and IV - in 20 (19.4%), 6 (5.8%) and 3 (2.9%) patients, respectively. Engel class I was achieved after anteromedial temporal lobectomy in 68% of cases, selective amygdaloghippocampectomy via standard approaches in 75% of cases, amygdaloghippocampectomy via subtemporal burr hole approach - in 80% of cases. Neurocognitive impairments after anteromedial lobectomy and selective amygdaloghippocampectomy were similar. At the same time, mental disorders de novo prevailed in the group of anteromedial lobectomy (p<0.05). There were no severe visual field disorders after subtemporal burr-hole access. In other cases, these disorders occurred in 36.2% of patients (p<0.05). There were 8 (7.8%) postoperative complications: 5 (10.2%) - after anterior temporal lobectomy, 3 (5.5%) - after selective surgeries via standard approaches. There were no complications after burr-hole surgery. CONCLUSION: Selective amygdaloghippocampectomy is not inferior to anteromedial lobectomy. Moreover, this procedure is associated with a lower risk of complications and adverse events.

[Brainstem arachnoid cyst: case report and review]. / Arakhnoidal'naya kista stvola mozga: opisanie klinicheskogo sluchaya i obzor literatury.

There are no literature data on brainstem arachnoid cysts in humans. OBJECTIVE: To describe the clinical case of brainstem (pontomesencephalic) arachnoid cyst and to analyze classification, pathogenesis, differential diagnosis and treatment of this pathology considering literature data and own experience. MATERIAL AND METHODS: A 29-year-old patient with pontomesencephalic arachnoid cyst is reported. The disease manifested in childhood with a headache aggravated by bending and pushing. Later, syncope, vegetative-visceral paroxysms, mild oculomotor disturbances, transient paresthesia and numbness of the left half of the face occurred. Headaches became significantly more severe and resulted nausea and vomiting. Magnetic resonance imaging (MRI) revealed a two-chambered arachnoid cyst. A smaller chamber was localized in interpeduncular cistern, a larger one - in brainstem. RESULTS AND DISCUSSION: Differential diagnosis included cystic glioma and Virchow-Robin space enlargement. Fenestration of the cyst wall within interpeduncular cistern was performed via right-sided pterional approach. The diagnosis was verified by histological examination. The follow-up period was 14 months. We observed postoperative cyst reduction confirmed by MR data and regression of all symptoms except for minimal signs of medial longitudinal fasciculus dysfunction. CONCLUSION: Correct surgical approach for brainstem arachnoid cyst complicated by progressive neurological deterioration is confirmed by postoperative regression of cyst and symptoms.

Intra-arterial Administration of Verapamil for the Prevention and Treatment of Cerebral Angiospasm.

From 2013 to 2017, at the Burdenko Institute of Neurosurgery, intra-arterial verapamil for treatment of cerebral vasospasm following intracranial hemorrhage after aneurysm rupture was administered to 35 patients (total 75 procedures). The age is from 8 to 77 years. All ruptured aneurysms were treated: in 26 cases with open approach-clipping-and in 9 cases with endovascular occlusion. The procedure was carried out from 0 to 11 days after the operation. Severity of spasm was assessed by angiography and TCDU. Efficacy of the administration was assessed by TCDU 1 h after the procedure and by clinical evaluation of the patient's condition. The dose of verapamil was 15-50 mg (on average 40 mg) per procedure/per carotid pool and depended on the data of TCDU and clinical and radiological picture. The procedure was performed repeatedly (1-5 times) according to the indications and depending on the patient's condition, with an interval of 24 h. The procedure was effective as a preventive measure for care of patients in the initial stage of cerebral ischemia and was ineffective with a formed focus of ischemia. Endovascular administration of verapamil for treatment of cerebral vasospasm is a safe technique which positively affects the overall recovery of such patients.

[Pseudoprogression of intracranial pilocytic astrocytomas and other low-grade gliomas. Literature review and case report]. / Psevdoprogressiya intrakranial'nykh piloidnykh astrotsitom i drugikh gliom nizkoi stepeni zlokachestvennosti. Obzor literatury, metaanaliz i klinicheskoe nablyudenie.

Tumor pseudoprogression is characterized by temporary tumor enlargement following radiotherapy with subsequent stabilization or regression without additional treatment. This phenomenon has been comprehensively described in patients with malignant gliomas. However, this phenomenon has not been sufficiently studied in patients with low-grade gliomas including pilocytic astrocytomas. In recent years, more and more researches devoted to this problem have appeared in the literature. It seems relevant to conduct a meta-analysis of these data in the modern literature.

[«Cavernous angiomas¼ of the brainstem. Clinical manifestations, diagnosis and treatment results]. / «Kavernoznye angiomy¼ stvola golovnogo mozga. Klinicheskie proyavleniya, diagnostika i rezul'taty lecheniya.

INTRODUCTION: In the current literature, brainstem hematomas and various types of vascular micromalformations are combined into the one group of diseases under the general name «cavernous angioma¼ (CA). This approach does not make it possible to accurately determine the indications for surgery and predict postoperative outcomes. OBJECTIVE: To analyze our own experience in the diagnosis and treatment of patients with the brainstem CA. MATERIAL AND METHODS: There were 515 patients with CA of the brainstem (surgery - 322, conservative treatment - 193 patients) with a follow-up period of more than 5 years. Follow-up survey implied neurological examination, analysis of Karnofsky score, MRI and CT data. RESULTS: We identified two main groups of patients after comparison of MRI data, intraoperative findings and biopsy data: group 1 - hematomas (191 patients, 59%), group 2 - CA (131 patients, 41%). Each group was characterized by own clinical and radiological features. Postoperative outcomes depended on the disease. Debridement of hematoma ensured early postoperative improvement in 63% of patients, no changes in 21% of cases and impairment in 16% of patients. Less favorable results were observed in patients with CA and no signs of hemorrhage. Clinical impairment occurred in 73% of cases, improvement - only in 5% of patients. The most significant regression of neurological symptoms in long-term postoperative period was observed in patients with hematomas (92% of patients). These ones noted much better clinical state compared with preoperative condition. CONCLUSIONS: The type of brain lesion is an important predictor to determine treatment approach. Postoperative outcomes differ significantly in patients with the brainstem hematoma and CA.

[Primary pineal melanocytoma: clinical case and literature review]. / Pervichnaia melanotsitoma pineal'noi oblasti: klinicheskii sluchai i obzor literatury.

Primary pineal melanocytomas are extremely rare pathologies and predominantly are clinically manifested by nonspecific symptoms of a pineal affect, which could be characteristic for tumors of different histological nature located in the same region. Also these tumors differ from other melanocytic tumors by their slow growth and relatively favorable clinical prognosis.

[Central neurocytomas: surgical treatment outcomes and new trends and approaches in the treatment]. / Tsentral'nye neirotsitomy golovnogo mozga: rezul'taty khirurgicheskogo lecheniia i novye tendentsii i strategii v lechenii.

AIM: Central neurocytomas of the brain are rare benign tumors of the cerebral lateral ventricles. The main treatment for them is surgical resection. Resection provides a long-term relapse-free period, but surgical intervention is associated with a number of significant difficulties due to the location, size, and blood supply features of these tumors. The postoperative period is often accompanied by hemorrhagic complications, impaired cerebrospinal fluid circulation, and worsening of neurological symptoms. PURPOSE: The study purpose was to evaluate the effectiveness of surgical treatment in neurocytoma patients, assess the risk of complications after neurocytoma resection, and develop techniques for their prevention. MATERIAL AND METHODS: The paper presents surgical treatment outcomes in 115 patients with central neurocytomas for the period from 2008 to 2017. The choice of a surgical approach and the surgical features are described in detail, and the radicality is assessed with allowance for the location and size of tumors. The immediate clinical outcomes of treatment are evaluated, complications are analyzed, and methods for prevention and treatment of complications are described. RESULTS: Analysis of the data revealed that the tumor was resected totally in 41 (36%) patients, subtotally - in 37 (32%), and partially in 37 (32%). The most common and dangerous complications were as follows: CSF circulation occlusion with the development of hydrocephalus in 23 (20%) patients; hemorrhage into the residual tumor, which required immediate revision of the surgical wound in most cases, in 25 (22%) patients. In the early postoperative period after tumor resection, almost all patients developed deterioration of condition with transient worsening of cerebral and focal symptoms. The degree and duration of this worsening were different. In 50% of cases, the postoperative condition was characterized by reduced voluntary activity, drowsiness or jitteriness, and motor or speech anxiety. CONCLUSION: We consider resection of neurocytomas as the main treatment option, despite the potential complications and effects of the operation.

[Oculomotor nerve neurinomas. Case reports and a literature review]. / Nevrinomy glazodvigatel'nogo nerva. Opisanie klinicheskikh sluchaev i obzor literatury.

Oculomotor nerve neurinoma not associated with neurofibromatosis type II is an extremely rare pathology. According to the topography, cisternal, cisternocavernous, cavernous, orbitocavernous, and orbital tumor groups are distinguished. The clinical picture of the disease is characterized mainly by either oculomotor disorders or pyramidal symptoms, depending on the tumor localization. Neurinomas of the oculomotor nerve rarely occur without oculomotor disorders. However, in some patients with these tumors, the third nerve function remains intact. In this paper, we present clinical cases of two patients with oculomotor nerve neurinomas and analyze the relevant literature.

[MR tractography in diagnosis and choice of a neurosurgical approach to basal ganglia tumors]. / MR-traktografiia v diagnostike i vybore neirokhirurgicheskogo dostupa pri opukholiakh podkorkovykh uzlov.

We describe two cases of surgical treatment of well-circumscribed basal ganglia tumors. The choice of a neurosurgical approach to a deep tumor was based on the MR tractography data and depended on the course and dislocation extent of the corticospinal tract. MR tractography provides information on the course and dislocation or destruction extent of the corticospinal tract running in the internal capsule and brainstem and clarifies the exact location of a tumor within the basal ganglia. This information promotes the choice of an optimal approach for radical resection of well-circumscribed tumor, leading to improvement in neurological symptoms and patient's quality of life.

[Preoperative and postoperative endocrine disorders associated with pituitary stalk injuries caused by suprasellar growing tumors]. / Éndokrinnye rasstroistva do i posle operatsii pri razlichnykh porazheniiakh steblia gipofiza supraselliarno rastushchimi opukholiami.

The pituitary stalk (PS) is a relatively thin bundle connecting the hypophyseal stalk to the pituitary gland; it consists of both axons of the hypothalamic nuclei (terminating in the neurohypophysis) and the system of portal vessels. Compression of the PS by a space-occupying lesion or its transection (forced or intended) during surgery may lead to the development of endocrine disorders: hypopituitarism, diabetes insipidus, and hyperprolactinemia. The modern literature lacks studies evaluating the severity of endocrine disorders depending on the PS condition before and after surgery. PURPOSE: The study purpose was to investigate endocrine disorders in patients with sellar region (SR) tumors and the PS that was compressed before surgery and preserved or transected during a neurosurgical intervention. MATERIAL AND METHODS: The study included 139 patients with various SR tumors. In 82 patients, a preoperatively compressed PS was preserved (41 patients with hormonal inactive adenoma (HIA) and 41 patients with suprasellar meningioma); in 57 patients, the PS was transected during surgery (46 patients with pituitary stalk craniopharyngioma and 11 patients with hormonally inactive endosuprasellar pituitary adenoma). The hormonal status (PRL, TSH, LH, FSH, fT4, cortisol, testosterone, or estradiol) was examined in all patients both before and after surgery. RESULTS: Hyperprolactinemia was preoperatively detected in 37% of patients with tumors compressing the PS. Elimination of PS compression (tumor resection) led to normalization of the PRL level in most patients and was not accompanied by aggravation of hypopituitarism symptoms. Transection of the PS caused panhypopituitarism in 100% of patients and diabetes insipidus in 93% of cases. After transection of the PS, hyperprolactinemia did not develop in 59% of patients with craniopharyngiomas (CPs) and 82% of patients with HIA. CONCLUSIONS: Given the difference in symptoms associated with compression and surgical transection of the PS, we believe that these two concepts should be clearly distinguished. The PS compression syndrome includes primarily hyperprolactinemia (37% of cases); elimination of PS compression leads to normalization of the PRL level in most patients and is not accompanied by aggravation of hypopituitarism symptoms. The PS transection syndrome in patients with CP and HIA led to the development of panhypopituitarism in all patients and permanent diabetes insipidus in most of them. The causes of the absence of hyperprolactinemia in many patients with PS transection require further research. The surgeon planning intraoperative PS transection to increase the radicality of surgery should be well informed about the consequences of this procedure for the patient's endocrine status.