[Stereotactic radiosurgery for epilepsy related to hypothalamic hamartoma]. / Stereotaksicheskaya radiokhirurgiya pri epilepsii u patsientov s gamartomoi gipotalamusa.

Hypothalamic hamartoma (HH) is a dysplastic lesion fused with hypothalamus and followed by epilepsy, precocious puberty and behavioral disorders. Up to 50% of patients become free of seizures after surgery, but various complications occur in 1/4 of cases. Radiofrequency thermocoagulation, laser interstitial thermal therapy and stereotactic radiosurgery (SRS) are alternative treatment options. OBJECTIVE: To define the indications for SRS in patients with HH and to clarify the irradiation parameters. MATERIAL AND METHODS: Twenty-two patients with HH and epilepsy underwent SRS at the Moscow Gamma-knife Center. A retrospective analysis included 19 patients with sufficient follow-up data. Median age of patients was 11.5 years (range 1.3-25.8). The diameter of irradiated HHs ranged between 5.5 and 40.9 mm. In 8 (36%) cases, the volume of hamartoma exceeded 3 cm3. Mean prescribed dose was 18±2.0 Gy, mean prescribed isodose - 48±4.2%. Median follow-up period was 14.8 months (range 3.4 - 96.1). RESULTS: Three (15.8%) patients were free of seizures. One patient (5.3%) improved dramatically after treatment with compete resolution of generalized seizures and experienced only rare emotional seizures (Engel IB). Eleven (57.8%) patients reported lower incidence of seizures. Severity and incidence of seizures were the same in 4 patients (21.1%). The best results were achieved in mean target dose over 20-22 Gy, minimal target dose over 7-10 Gy, covering by the prescribed dose of at least 70-80% of hamartoma volume, as well as in patients with the prescribed dose of 12 Gy delivered to almost entire volume of tumor. None patient had any complications after SRS. CONCLUSION: SRS is safe regarding neurological, endocrine or visual disturbances. Careful patient selection for SRS makes it an effective option for HH-related epilepsy. The best candidates for SRS are children with seizures aged over 1 year, hamartoma <3 cm3 and area of fusion with hypothalamus <150 mm2.

[Magnetoencephalography in the presurgical evaluation of patients with drug-resistant epilepsy].

Magnetoencephalography (MEG) in combination with structural MRI (magnetic source imaging, MSI) plays an increasingly important role as one of the tools for presurgical evaluation of medically intractable focal epilepsy. The aim of the study was to compare the MSI and commonly used video EEG monitoring method (vEEG) in their sensitivity to interictal epileptic discharges (IED) in 22 patients with drug resistant epilepsy. Furthermore, the detection and localization results obtained by both methods were verified using the data of electrocorticography (ECoG) and postsurgical outcome in 13 patients who underwent invasive EEG monitoring and surgery. The results showed that MSI was superior to vEEC in terms of sensitivity to IED with difference in sensitivity of 22%. The data also suggested that MSI superiority to vEEG in detecting epileptic discharges might, at least partly, arise from better MEG responsiveness to epileptic events coming from the medial, opercular and basal aspects of cortical lobes. MSI localization estimates were in the same cortical lobe and at the same lobar aspects as the epileptic foci detected by ECoG in all patients. Thus, magnetic source imaging can provide critical localization information that is not available when other noninvasive methods, such as vEEG and MRI, are used.

[Are the medulloepithelioma, ependymoblastoma and embryonal tumor with multilayered rosettes the same entity?].

Medulloepithelioma is a rare malignant tumor arising in cerebral hemispheres. Microscopically, medulloepithelioma is characterized by epithelial structures that mimic the embryonic neural tube. Immunohistochemical analysis revealed that tumor cells are immunopositive for LIN28A and fluorescence in situ hybridization showed an amplification of a miRNA cluster at 19q13.42. Presence of these both aberrations suggesting that medulloepithelioma, ependymoblastoma and embryonal tumor with multilayered rosettes are the same entity.

[Stereotactic radiotherapy and radiosurgery in treatment of patients with deep-seated pilocytic astrocytomas].

Pilocytic astrocytoma (PA) is a low-grade glial tumor (WHO grade I) with predominant occurrence in pediatric patients. According to many authors, stereotactic radiosurgery (SRS) and radiotherapy (SRT) promote long-term remission or retardation of tumor progression in patients with in inoperable lesions after incomplete resection or recurrence. Therefore it is essential to determine the role of SRS and SRT in complex management of patients with deep-seated PA. Since April 2005 till May 2010 101 patient with intracranial PA was treated in department for radiation therapy of Burdenko Neurosurgical Institute. The series consisted of 70 pediatric patients (below 17 years inclusively) and 31 adults, of them--51 male and 50 female patients. Mean age was 15.1 years (9.8 years in children and 28.7 in adults). In 90 patients (89.2%) tumors were previously histologically verified (tumor resection in 83 cases and biopsy in 7). In 11 (10.8%) patients diagnosis of PA was based on clinical and neurovisualization data. In most cases SRT (66 (66.3%) patients) was preformed, the rest 35 (34.7%) patients were treated by SRS. Median follow-up from the onset of disease reached 52 months (2-228 months). Catamnestic data were available in 88 (87%) patients. By the end of catamnestic follow-up (December 2010) 87 (98.8%) patients treated by SRS and SRT were alive. Median follow-up from the start of radiation treatment was 22.7 months (6-60 months). Progression of tumor was observed in 20 patients (22.7%), in 18 of them due to cyst growth. 18 patients were reoperated. In 12 operated patients histological examination and its comparative analysis were performed. We found that alterations in the tumor tissue, accompanied by regression of solid component and progression of cystic portion, represent reactive-degenerative changes in the tumor as a consequence of radiation-induced pathomorphism. SRS and STR are effective techniques for treatment of patients with primary and recurrent PA despite regardless of localization of the tumor. There procedures should be performed shortly after non-radical resection. Control of tumor growth by the present time (median follow-up is 22.7 months) reaches 98%. "Progression" of the tumor due to enlargement of cystic portion shortly after SRT and SRS represents reactive-degenerative alterations in the tumor tissue and should not be evaluated as true recurrence; without neurological deterioration these cases do not require special treatment.

[Application of SPECT/CT in neurosurgical practice].

The paper presents the experience of application of single-photon emission computed tomography (SPECT) and CT in neurosurgery. Combination of these two techniques in the single system provides higher precision of both methods. The novel technique allows assessment of tumor spread in the brain, differential diagnosis of tumor regrowth and radiation-induced necrosis, evaluation of cerebral perfusion in epilepsy, traumatic brain injury (TBI), and diagnostics of secondary CNS lesions. Examples of primary diagnosis, dynamic follow-up and differential diagnosis of cerebral neoplasms, localization of epileptogenic foci in planning of surgery, prediction of outcome after TBI and evaluation of spread of metastatic skeletal involvement and further application of acquire data are presented.

[Topical features of speech disorders in children with focal cortical dysplasia and symptomatic epilepsy].

We studied speech function in 11 patients with focal cortical dysplasia (FCD) of different localization. The character of speech disorders was strongly correlated with the time of seizure onset and their frequency, while the localization of dysplasia did not play a significant role. The speech remained intact during seizures in the school age and during the relatively rare (weekly or monthly) seizures. The complete disappearance of speech after the period of normal development occurred in the daily multiple secondary-generalized seizures and resembled the previously described Landau-Kleffner syndrome ("aphasia-epilepsy"). Based on the literature and own data, the authors suggest that such global speech disorders can not be considered as aphasia, i.e., the disorder due to the focal lesions of speech brain areas. The authors did not reject the possibility of the development of aphasia in epileptic patients but only in those cases when the epileptic activity confined to mostly speech areas. Global speech disorders (up to the complete disappearance of impressive and expressive speech) at any localization of epileptic focus developed during the negative rearrangement of the speech functional system as a whole. These speech disorders are often accompanied by the acquired epileptic frontal syndrome. That is, in the first place are the most phylo- and ontogenetically young functional systems, namely, speech and regulatory functions, the damage of which emerges as a frontal syndrome. At the same time, the old consolidated pre-speech connections remain. Presumably, in this view, in cases of global speech disorders and speech disappearance, it is more correctly to substitute the terms "aphasia-epilepsy" and "total aphasia" for the familiar term "regression of speech development".

[A new entity in WHO classification of tumors of the central nervous system--embryonic tumor with abundant neuropil and true rosettes: case report and review of literature].

Embryonic tumor with abundant neuropil and true rosettes (ETANTR) is a very aggressive rare tumor with unique histologic and molecular features occurring in very young children. At present approximately 80 cases of ETANTR have been documented in the literature since first description in 2000. We report seven patients with ETANTR below 4 years of age who underwent surgical resection in the Burdenko Neurosurgery Institute between 2005 and 2010. Four children have received different modality chemotherapy and radiotherapy and two patients were treated by chemotherapy alone. One child did not receive any adjuvant treatment. All children had local relapses, two of them were operated twice. A 2 year old girl underwent subtotal resection thrice. Histological examination showed that all tumors were composed of true multilayered rosettes admixed with large areas of paucicellular neuropil. By analysis of recurrences we have found that large areas of neuropil and number of true rosettes were lost and tumors acquired a resemblance to central nervous system primitive neuroectodermal tumors. In four cases frozen tumor material was available for array-based comparative genomic hybridization, which discovered trisomy of chromosome 2 and amplification at the 19q13.42 chromosome locus. Fluorescence in situ hybridization revealed amplification at the 19q13.42 chromosome locus in all cases.

[Hemostatic disorders caused by chronic use of valproic acid in neurosurgical patients. Thromboelastographic monitoring].

The paper gives the results of analyzing the hemostatic system in 26 patients with various neurosurgical diseases on the basis of routine laboratory biochemical tests and thromboelastographic indicators. In all the patients, the pattern of the disease contained an epilepsy syndrome that required mono- or combination therapy with valproic acid. Laboratory indicators of clinical hypocoagulation were found to develop during the use of valproic acid, and its monotherapy in particular. Hemorrhagic complications were also analyzed in not only the immediate, but also late postoperative period (for as long as 6 months after surgery). Two cases of severe late complications, such as formation of chronic subdural hematomas requiring surgical intervention, were diagnosed in the valproate monotherapy group. A tactic using a thromboelastographic technique is proposed to prepare these patients for further neurosurgical intervention.

[Stereotactic radiosurgery in treatment of patients with hypothalamic hamartomas].

Hypothalamic hamartoma (HH) is malformation of the brain manifesting by paroxysmal disorders (gelastic seizures) and endocrine disorders (mostly precocious sexual development). Surgical resection of HH is associated with the risk of severe neurological and neuroendocrine complications. Alternative ways of treatment are being investigasted. Stereotactic radiosurgery is one of the leading techniques in treatment of pharmacoresistant seizures due to high effectiveness and low complication rate. Since 2005 till 2009 7 patients with HH were treated in Burdenko Moscow Neurosurgical Institute. Age of patients varied between 9 months and 20 years 9 mean - 8.5 years). In all cases the disease manifested by gelastic seizures with frequency differing between 2-3 per months and 17 per day. All patients received long-term combined anticonvulsant treatment (using valproates, carbamazepine, lamotrigine, oxcarbazepine, topiramate) with temporary and insufficient effect or without any effect. In 4 patients frequency of seizures increased during anticonvulsant therapy. I patient had been operated (partial resection of HH) with temporary effect which consisted of decrease in frequency of seizures for 8 months; later frequency of paroxysms increased. Main indications to radiosurgical treatment included progressive course of disease, low effectiveness of anticonvulsant therapy and high risk of direct surgical treatment. 6 patients were treated using linear accelerator "Novalis" and 1 using "Cyber-knife". Treatment was performed under pharmacological sedation (midazolam, ketamine). Marginal dose was 11-18 Gy (mean 15.7 Gy). Volume of hamartomas was 0.3-3 cm3. Follow-up period varied between 3 and 50 months. Decreased frequency of seizures was observed in 100% of cases. Stereotactic radiosurgery is an effective and safe method of treatment for HH and may be considered as treatment of choice for pharmacoresistant seizures caused by HH.

[Endoscopic ventriculostomy of the third ventricle in infants of less than 2 years of age].

The efficiency of endoscopic ventriculostomy (EVS) of the third ventricle is noticeably lower in small children than in adults and many surgeons prefer to shunt them despite the fact that revision has to be resorted to in half of the cases. Recent reports on the successful use of EVS in infants under 2 years of age have made the authors to revise traditional views. A sample of 20 babies (mean age 9.7 +/- 4.3 months) with obstructive triventricular hydrocephalus (HC) undergone EVS at the Academician N. N. Burdenko Research Institute of Neurosurgery, Russian Academy of Medical Sciences, in 1999 to 2006. The cause of HC was intracranial infection (n = 7), hemorrhage (n = 4), aqueduct stenosis (n = 4), Galen's vein aneurysms (GVA) (n = 3), and posterior third ventricular tumors (n = 2). Postoperative follow-ups averaged 15 months. There were no deaths; overall morbidity was 10%. By and large, the efficiency of EVS was 47%. At the same time, the best results were observed in babies with GVA (100%) and aqueduct stenosis (75%). The results were significantly worse in patients with the postinflammatory (33%) and posthemorrhagic (0%) etiology of HC. In addition to the etiology, the efficiency of EVS correlated with factors, such as prolapse of the third ventricular floor into the interpeduncular cistern, the thickened and rigid floor of the third ventricle, and an analysis excluding 3 babies with GVA established a direct correlation between the dysfunction of EVS and the early manifestation of HC. Postoperative clinical improvement was attended by decreases in the anterior-posterior horn ratio in all cases and in the sizes of the third ventricle.

[Cerebrospinal fluid dynamics in chronic obstructive hydrocephalus before and after successful endoscopic third ventriculostomy].

OBJECTIVE: to describe cerebrospinal fluid dynamics in chronic obstructive hydrocephalus before and after successful endoscopic third ventriculostomy (ETV). MATERIALS AND METHODS: 8 patients (7-21 years old) with chronic obstructive hydrocephalus due to tectal plate glioma were investigated before and after successful ETV. Apart from clinical and MRI assessment ICP-monitoring (ICP0) and intraventricular infusion studies were performed as well as upright ICP (ICP90) was investigated preoperatively and on 1st and 7th postoperative days (POD). Dynamic changes were assessed using Wilcoxon matched pairs test. RESULTS: There were no complications. MRI demonstrated functional ventriculostomy and reduced ventricle size in all cases. At follow-up all ETV's were considered clinically successful. By the 7th POD ICP0 showed tendency to reduction (p = 0.07) and ICP90 reduced significantly (p = 0.02). Significant reduction of Rcsf was evident by the 1st POD (p = 0.03) and was maintained until the 7th POD (p = 0.02). Elastance coefficient and compliance (as measured during infusion study) didn't change significantly in relation to ETV. In all the 3 cases when computerized ICP monitoring was used reduction of ICP pulse amplitude (AMP), AMP/ICP slope and RAP was noted by the 7-th POD which most probably reflects reduction of intracranial elastance. CONCLUSION: Effect of ETV in chronic obstructive hydrocephalus cannot be explained exclusively by its influence on ICP0; clinical improvement can possibly be attributed also to normalization of ICP90 and Rcsf, reduction of intracranial elastance and increase of cerebral blood flow reserve capabilities. There may be a pathophysiological ground for ETV in obstructive hydrocephalus with normal ICP.

[Complications and failures of endoscopic ventriculostomy of the third ventricle]. / Oslozhneniia i neudachi éndoskopicheskoi ventrikulostomii III zheludochka.

The study was undertaken to elucidate the poor outcomes of endoscopic ventriculostomy of the third ventricle (EVTV), including complications and dysfunctions. A series of 249 consecutive EVTV (the mean age of 15 years in 247 patients) made at the Institute of Neurosurgery in 1995 to 2003 was analyzed. The causes of hydrocephalus were benign tumors in 95 (38%) patients, stenosis of the aqueduct of the cerebrum in 73 (29%), malignant tumors in 63 (25%), and other causes in 18 (7%) cases. Obstruction in the posterior cranial fossa was present in 12 (5%); prior to EVTV, 24 (10%) and 36 (15%) patients had undergone craniotomy and bypass surgery, respectively; 12 (5%) patients had sustained subarachnoidal or intraventricular hemorrhage, 21 (8%) had intracranial infections. The follow-up averaged 16 months. Its results showed that 40 complications occurred in 34 (14%) patients. Seven (3%) patients required unplanned operations; transient and persistent neurological deficits were present in 15 (6%) and 2 (1%), respectively; there were no surgery-related deaths. Meningitis occurred in 14 (6%) cases; its risk was higher in patients having a history of intracranial infections (p = 0.02); meningitis was absent in patients with benign tumors (p < 0.01). Intracranial hemorrhages occurred in 7 (3%) cases; 2 of them required surgical treatment. Moreover, there were 6 (2%) wound complications (4 cases of wound cerebrospinal fluid discharge); 5 (2%) EVTVs were prematurely discontinued; isolated neurological deficit occurred in 6 (2%), single seizures were observed in 2 (1%). There were early dysfunctions in 16 (6%) cases; their risk was associated with obstruction in the posterior cranial fossa (p = 0.04) and with the technical result of an operation (p < 0.01). Late dysfunctions occurred in 21 (8%) cases, on the average, after 12 months of EVTV; their risk was higher in patients with malignant tumors (p = 0.04). It is concluded that indications for EVTV should be substantiated by the good chance of having a steady-state surgical success, by an overall prognosis, and staffs experience. The history of intracranial infections requires careful preoperative studies. Obstruction at the level of the posterior intracranial fossa is a relative contraindication to EVTV due to a low chance of having a success. The high risk for late dysfunctions in patients with malignant tumors requires a more strict choice of indications in this group. If there is anastomotic dysfunction, EVTV may be a good alternative to shunt revision.

[Iatrogenic metastasis of pineal tumors]. / Iatrogennoe metastazirovanie opukholei pineal'noi oblasti.

Malignant pineal tumors (PT) tend to metastasize. In rare cases, this process is provoked by surgery. This paper describes four cases of iatrogenic metastasis of PT. Metastasis occurred: a) along the surgical approach path after tumor removal in 2 cases; b) along the biopsy cannula path; and c) along the ventriculoperitoneal catheter into the abdomen. The sources of metastases were pineoblastoma (n = 1), malignant teratoma (n = 1), germinoma (n = 1), and malignant germ-cell tumor of unknown genesis (n = 1). To prevent this complication due to high-grade PT, such as malignant germ-cell tumors and pineoblastomas, radiation of the whole brain, besides the sites of a tumor should be performed and, in some cases, in combination with chemotherapy.

[Results of endoscopic ventriculostomy of the III ventricle in the treatment of occlusive hydrocephalus]. / Rezul'taty éndoskopicheskoi ventrikulostomii III zheludochka v lechenii okkliuzionnoi gidrotsefalii.

The paper presents data of a retrospective analysis of the outcomes of endoscopic ventriculostomy of the 3rd ventricle, obtained in a consecutive series of 120 patients aged 5 months to 58 years who had occlusive hydrocephalus and operated on at the Research Institute of Neurosurgery, Russian Academy of Medical Sciences, in 1995-2000. In most cases (n = 112), hydrocephalus was caused by a block at the level of the cerebral aqueduct. In more than 50% of the patients, different tumors were responsible for occlusion. In 96 (80%) cases, the operation led to the elimination of occlusion and to the regression of symptoms just after surgery. Complications were few and observed in 19 patients, ventriculitis (n = 7) and intracranial hemorrhages (n = 6) being most common. No death occurred. Seventy three patients were followed up for 1 month to 5 years (mean 1.5 years). Eliminated occlusion and steady-state remission were found in 64 (87.7%) cases. Improvement was strongly correlated with an increase in the reserve craniovertebral content capacity estimated by measuring the pulse amplitude of blood flow in the tentorial sinus in body position-changing tests. In 9 patients, the symptoms of hydrocephalus remained or recurred after short-term improvement. In 3 of them, this occurred with anatomically competent anastomoses between the 3rd ventricle and cisterns. In the other 6 cases, the obliteration and anatomic incompetence of ventriculostoma were responsible for a relapse. In 8 of the 9 patients, shunting had to be made subsequently in the period of 1 to 6 months. The paper also considers some biophysical aspects of cerebrospinal fluid circulation and discusses indications for endoscopy. It is concluded that endoscopic ventriculostomy of the 3rd ventricle is the method of choice in the treatment of patients with obstructive hydrocephalus.

[Use of the navigation system Stealth Station(TM) for removal of brain neoplasm]. / Ispol'zovanie navigatsionnoi sistemy Stealth Station(TM) dlia udaleniia opukholei golovnogo mozga.

The paper analyzes the authors' initial experience with the Stealth Station navigation system (Medtronic-Sofamor Danek, USA) during neurosurgery for intracranial tumors and outlines its techniques. Twenty eight patients with various brain tumors were operated on. Thirteen patients had tumors of the skull base (meningiomas, chordomas, paragangliomas, fibrous dysplasia). Twelve patients showed various intracerebral tumor-forming processes (gliomas, cavernous angiomas, and metastizing carcinomas). The navigation system ensured resection of these tumors. It was used in 2 other patients with gliomas and in 1 patient with cystic craniopharyngioma for their stereotactic puncture, biopsy, and drainage. The Stealth Station proved to be an effective tool for preoperative planning of cranial neurosurgical operations and their intraoperative guidance. Strict observance of the protocols of preoperative preparation ensures a high accuracy and facilitates search for and identification of anatomic guides. Only in 1 patient with surface glioma involving the central gyri, its resection was followed by hemiparesis that subsequently progressed. In the remaining 27 cases, the operation ran smoothly and caused no new neurological defect. The brain-shift phenomenon is the principal limitation of accuracy of the intraoperative system. This problem is less evident in skull-base surgery where the system was effectively used for critical structural location. Also, it can be safely employed for elimination of slight deep lesions to protect the brain and to minimize its injury via approach to a tumor through the brain parenchyma.

[Endoscopic ventriculocisternostomy: methods and equipment]. / Endoskopicheskaia ventrikulotsisternostomiia: metodika i oborudovanie.

The paper describes endoscopic ventriculocisternostomic techniques. It discusses the problems associated with the optimum configuration of equipment and tools, as well as with the basic principles of postoperative management of patients. Emphasis is laid on the engineering features and on the prevention of complications. The paper is based on 4-year experience gained in using this procedure at the Academician N. N. Burdenko Research Institute of Neurosurgery, Russian Academy of Medical Sciences, to treat over 60 patients with acquired occlusive hydrocephalus.

[Endoscopic fenestration of median supratentorial cerebrospinal fluid cysts]. / Endoskopicheskaia fenestratsiia sredinykh supratentorial'nykh likvornykh kist.

Mid-supratentorial liquor cysts are a relatively rare and generally congenital abnormality of the cerebral ventricles and subdural spaces. The data and views available in the literature on rational surgical policy is contradictory. The authors' experience in treating 16 patients was used to consider whether endoscopic techniques can be employed for invasive fenestration of the cysts. The goal of surgery was to remove the masses caused by cystic malformations and their local compression of the brain via fenestration of the walls of the cysts and via communication of their cavities with the ventricles and cisterns. There were solitary cysts in all cases (arachnoidal cysts of the interpedicular cistern and the third ventricle in 9; cysts of the ventricular septum in 4, ependicular cysts of the lateral ventricle in 2, and cysts of the celiac plexus of the third ventricle in other 2 cases, in 1 cases a liquor cyst was located in the midbrain thickness). The clinical picture was characterized by a combination of hypertensive, hydrocephalic and focal symptoms of damages to the hypothalamic and thalamic structures and the adjacent formations of the brain (pyramidal and extrapyramidal disorders, ataxia, chiasmal syndrome, metabolic and endocrine disorders, etc.). In 6 cases these symptoms were persistent despite preimplanted VP anastomosis. Rigid Storz endoscopes (Germany) with an external coat, 6 mm in diameter, and a Codman fibroendoscope (USA), 4 mm in diameter, were employed. Cystic ventriculostomy and cystic ventriculocisternostomies were made in 11 and 6 patients, respectively; one patient underwent endoscopic resection of the walls of an ependymal cyst. In one patient with signs of decreased liquor resorption, endoscopic fenestration was concurrently developed into a ventricle-peritoneal anastomosis. In other 4 anastomosis-dependent patients, the preimplanted mechanically consistent bypass system was left at its site. In 2 of these cases, cystic ventriculostomy was supplemented by ventricular septal fenestration and third-ventricular bottom perforation. Twelve patients were followed up for 6 to 36.5 months (mean 15 months). There has been no information about 6 patients since their discharge. In 12 (66.5%) surgery yielded expected results and the fenestration of cystic walls was followed by their retraction and a steady-state regression of local and/or hypertensive symptoms. In 5 (28%) patients, the complaints and clinical data remained unchanged despite although incomplete but objective cystic relaxation. This was most frequently noted in patients (n = 4) with arachnoidal cysts of the interpedicular cistern and the third ventricle who had endocrine disorders. In one case the operation was stopped due to bleeding. Totally, 5 patients were found to have complications (hemorrhage, ventriculitis). None patient died. Some aspects of indications for endoscopy and surgical techniques are considered. It is concluded that endoscopic internal bypass surgery in patients wit median cystic liquor malformations is the treatment of choice. When equipment is adjusted, fenestration of the membranous walls of these cysts by using an endoscope is reliable and safe. Such patients may be recommended endoscopic technology used as the method of choice.