A Comparison of Word Embeddings to Study Complications in Neurosurgery.

Our study aimed to compare the capability of different word embeddings to capture the semantic similarity of clinical concepts related to complications in neurosurgery at the level of medical experts. Eighty-four sets of word embeddings (based on Word2vec, GloVe, FastText, PMI, and BERT algorithms) were benchmarked in a clustering task. FastText model showed the best close to the medical expertise capability to group medical terms by their meaning (adjusted Rand index = 0.682). Word embedding models can accurately reflect clinical concepts' semantic and linguistic similarities, promising their robust usage in medical domain-specific NLP tasks.

Surgical treatment of ruptured right middle cerebral artery mycotic aneurysm and central nervous system aspergillosis: Clinical case and literature review.

BACKGROUND: Central nervous system (CNS) aspergillosis is more often met in patients with expressed immune suppression. Still, in 50% of cases of meningitis caused by Aspergillus spp., it is observed in patients without expressed immune suppression. The prognosis of CNS aspergillosis is unfavorable with the general rate of lethality around 70%. CASE DESCRIPTION: Clinical case of a 58-year-old man who developed an Aspergillus abscess in the chiasmosellar region and an associated mycotic aneurysm of the right middle cerebral artery (MCA) and intracerebral hemorrhage. Microsurgical clipping of the fusiform-ectatic aneurysm of the right MCA in the conditions of rupture was performed. An extra-intracranial micro anastomosis was formed on the right. An open biopsy of the neoplasm in the chiasmosellar region was made. The neoplasm was yellow and destroyed the bone plate of the skull base. Biopsy results: Mycotic lesion (aspergillosis). The analysis of surgical treatment for mycotic aneurysms in the acute period of hemorrhage in patients with aspergillosis revealed a high rate of lethality. The issue of the feasibility and effectiveness of complicated revascularization interventions in the patients with hemorrhage and aspergillosis remains unsolved. CONCLUSION: The lack of generally accepted tactics of the treatment of this pathology requires further studies and systemic analysis. A high risk of the lethal outcome in patients with invasive mycotic infection and rupture of mycotic aneurysm highlight the importance of timely diagnostics and the beginning of antimycotic therapy. WThe issue of the evaluation of the revascularization methods effectiveness in patients after surgical treatment of a mycotic aneurysm associated with cerebral aspergillosis remains poor.

Severe vancomycin-induced thrombocytopenia in a patient with meningitis.

Vancomycin is a widely used antibiotic and rarely can cause drug-induced thrombocytopenia. A patient with hospital-acquired meningitis after neurosurgery was treated with systemic and intrathecal vancomycin. On 9th day of antibiotic treatment, the patient's platelets dropped to 0.68×109/L. Multiple platelet transfusions had minimal influence on platelet count. After cessation of vancomycin therapy, platelets returned to normal values without any additional interventions. Diagnosis of vancomycin-induced thrombocytopenia was confirmed by detection of drug-dependent antiplatelet IgG antibodies.

Internal Carotid Artery Injury in Transsphenoidal Surgery: Tenets for Its Avoidance and Refit-A Clinical Study.

One of the most serious/potentially fatal complications of transsphenoidal surgery (TSS) is internal carotid artery (ICA) injury. Of 6230 patients who underwent TSS, ICA injury occurred in 8 (0.12%). The etiology, possible treatment options, and avoidance of ICA injury were analyzed. ICA injury occurred at two different stages: (1) during the exposure of the sella floor and dural incision over the sella and cavernous sinus and (2) during the resection of the cavernous sinus extension of the tumor. The angiographic collateral blood supply was categorized as good, sufficient, and nonsufficient to help with the decision making for repairing the injury. ICA occlusion with a balloon was performed at the injury site in two cases, microcoils in two patients, microcoils plus a single barrel extra-intracranial high-flow bypass in one case, stent grafting in one case, and no intervention in two cases. The risk of ICA injury diminishes with better preoperative preparation, intraoperative navigation, and ultrasound dopplerography. Reconstructive surgery for closing the defect and restoring the blood flow to the artery should be assessed depending on the site of the injury and the anatomical features of the ICA.

[Changes in the morphological structure of giant prolactinoma during treatment with cabergoline].

Currently, cabergoline therapy is the main method of treatment with prolactin. The use of the drug in most cases leads to tumor regression, normalization of prolactin levels and restoration of gonadotropic function. The mechanism of its impact on tumor cells in vivo, which is dynamically traced in the same human tumor, is the case of considerable interest. We observed a 30-year-old patient who was operated on twice for a giant prolactinoma before and on treatment by cabergoline. The morphological study after the first surgery (before introducing of cabergoline therapy) revealed a prolactin-positive pituitary tumor with a Ki-67 labeling index of 8% and with strong expression of dopamine type 2 receptors (D2R), CD31 and CD34. After 4 months, during which the patient received cabergoline at a dose starting from 0.5 mg to 1.5 mg per week, a second transsphenoidal surgery was performed with subtotal removal of residual tumor tissue. During the morphological study of the second biopsy sample, the tumor retained a pronounced immunopositivity to prolactin and D2R, with a decrease in the labeling index Ki-67 to 2%, as well as a decrease in the expression of CD31 and CD34. Subsequent cabergoline therapyresulted in persistent normoprolactinemia, restoration of androgen (and reproductive) status, and no tumor recurrence over a 10-year period on cabergoline treatment. Thus, one of the mechanisms of effect of cabergoline that leads to tumor regression is a decrease in the proliferative index and angiogenesis of the tumor.

Decrease of Proliferative Potential and Vascular Density of Giant Prolactinoma in Patients Treated with Cabergoline.

INTRODUCTION: Currently, cabergoline therapy is the main treatment for prolactinomas. The use of the drug in most cases leads to regression of the tumor, normalization of prolactin (PRL) levels, and restoration of gonadotropic function. The mechanism of its action in tumor cells "in vivo" tracked in dynamics in the same human tumor is of considerable interest. MATERIALS AND METHODS: A 30-year-old male was admitted to N.N. Burdenko National Medical Research Center of Neurosurgery. An magnetic resonance imaging (MRI) revealed a giant pituitary adenoma. The level of PRL was more than 5000 mU/l (30-360) (serum dilution was not used to determine PRL). Transcranial microsurgical removal of the tumor was performed. He was treated by cabergoline after surgery. Endoscopic transsphenoidal approach was repeated with subtotal removal of the rest of the tumor. Morphological and immunohistochemical studies of the tumor were done. RESULTS: A morphological study revealed PRL-positive tumor with a Ki-67 LI of 8% with a distinctive expression of D2R, CD31, and CD34 markers. Control MRI in 3 months after surgery revealed remnants of a tumor of endoinfrasellar localization, the tumor remainders were found in endoinfrasellar localization. The tumor retained pronounced immunopositivity to PRL and D2R and a decrease in the Ki-67 to 2% and in the expression of CD31 and CD34. Subsequent therapy with cabergoline resulted in persistent normoprolactinemia, restoration of androgenic function, and absence of tumor recurrence during the 10-year follow-up period. CONCLUSIONS: Cabergoline is an effective treatment for prolactinoma, which leads to tumor regression. One of its mechanisms is the reduction of the proliferative index and tumor angiogenesis.

Endoscopic Transsphenoidal Approach in Treatment of Germinomas of the Chiasmosellar Region.

INTRODUCTION: Germinogenic central nervous system (CNS) tumors represent a heterogeneous group of tumors, constituting approximately 0.4% of all primary brain tumors. Removal of the tumor has no prognostic value. In "pure" primary germinomas of the CNS, the alpha-fetoprotein and human chorionic gonadotropin levels are within normal limits, and no specific biochemical tumor markers currently exist for this tumor type, making histological verification crucial for the choice of treatment tactics. When the tumor is located in the chiasmosellar region, one of the possible verification methods is endoscopic endonasal transsphenoidal biopsy. OBJECTIVE: The main objective of the study is to demonstrate the feasibility and safety of endoscopic transsphenoidal approach for histological verification of primary germinomas of the CNS with chiasmosellar localization. MATERIALS AND METHODS: The current study includes 13 patients with "pure" germinomas of the chiasmosellar region who underwent endoscopic endonasal surgical interventions with subsequent treatment according to the "Germinoma 2008" protocol. RESULTS: The extent of surgical intervention ranged from biopsy (4) to partial (5) and total (4) removal of the tumor. In all cases, histological verification of the diagnosis was achieved and none of the patients presented with cerebrospinal fluid leaks and/or meningitis in the postoperative period, allowing to evaluate endoscopic intervention in our patient series as safe and effective. Two out of 13 patients were lost to follow-up. CONCLUSION: The endoscopic endonasal approach for histological verification and removal of chiasmosellar region germinomas is safe, and in some cases, less traumatic for the patient than transcranial and transventricular approaches.

Amygdalohippocampectomy via the Lateral Extended Transsphenoidal Endoscopic Approach Through the Pterygopalatine Fossa: An Anatomic Study.

BACKGROUND: The lateral extended transsphenoidal endoscopic approach (LETEA) is used to remove tumors located lateral to the cavernous segment of the internal carotid artery under direct visual control and provides access to Meckel cave, pterygopalatine fossa, medial part of the middle cranial fossa, and orbit. We describe an extended transsphenoidal approach to the amygdalohippocampectomy through the pterygopalatine fossa. METHODS: The LETEA to the middle cranial fossa through the pterygopalatine fossa was studied on 3 injected human cadavers at the Burdenko Neurosurgery Institute in Moscow, Russia. RESULTS: LETEA and trepanation of the greater wing of the sphenoid bone allow access to the medial part of the middle cranial fossa. Medial segments of the temporal lobe (hippocampus and amygdala) and the temporal pole were removed under guidance of the 45° angled endoscope. CONCLUSIONS: LETEA through the pterygopalatine fossa is minimally invasive and provides direct access to the temporal pole and medial part of the temporal lobe. This approach may reduce risk of neurologic deficit and help to avoid cosmetic defects in the frontotemporal region associated with injury to temporal muscle and facial nerve injury as can occur during transcranial approaches. Disadvantages that limit application of LETEA include risk of cerebrospinal fluid leak and skills needed for manipulation in a narrow and deep surgical field with angled 30° and 45° endoscopes.

Endoscopic Endonasal Surgery of Epidermoid Cysts of the Chiasmatic Region.

BACKGROUND: Despite the rarity of epidermoid cysts in the chiasmatic region, their surgical treatment is particularly complicated because of the tendency toward massive dissemination of the epidermoid masses along cerebrospinal fluid pathways and significant deviation of the tumor from the midline. OBJECTIVE: The purpose of the present work is evaluation of the role of extended transsphenoidal endoscopic endonasal approaches in the surgery of epidermoid cysts. METHODS: The study included 6 patients with epidermoid cysts in the chiasmatic region who were operated on at the Burdenko Neurosurgery Institute in the last 5 years using an anterior extended transsphenoidal endoscopic endonasal approach. RESULTS: The epidermoid masses were totally removed in 5 patients, but in no patient was it possible to completely remove the epidermoid cyst capsule. Visual deterioration was not noted in any patient, nor did new focal neurologic symptoms appear. One of the patients developed hypopituitary disorders in the postoperative period. No recurrence of the epidermoid cysts was observed during the follow-up period. CONCLUSIONS: Removal of epidermoid cysts in the chiasmatic region using an anterior extended transsphenoidal endoscopic approach may be an alternative to transcranial microsurgery operations. This technique is widely accepted as an approach to this area.

Extended Transsphenoidal Endoscopic Endonasal Surgery of Suprasellar Craniopharyngiomas.

OBJECTIVE: The endoscopic extended transsphenoidal approach for suprasellar craniopharyngiomas may be a really alternative to the transcranial approach in many cases. The authors present their experience with this technique in 136 patients with craniopharyngiomas. METHODS: From the past 7 years 204 patients with different purely supradiaphragmatic tumors underwent removal by extended endoscopic transsphenoidal transtuberculum transplanum approach. Most of the patients (136) had craniopharyngiomas (suprasellar, intra-extraventricular). The patients were analyzed according to age, sex, tumor size, growth and tumor structure, and clinical symptoms. Twenty-five patients had undergone a previous surgery. The mean follow-up was 42 months (range, 4-120 months). The operation is always performed with the bilateral endoscopic endonasal anterior extended transsphenoidal approach. RESULTS: A gross-total removal was completed in 72%. Improvement of vision or absence of visual deterioration after operation was observed in 89% of patients; 11% had worsening vision after surgery. Endocrine dysfunction did not improve after surgery, new hypotalamopituitary dysfunction (anterior pituitary dysfunction or diabetes insipidus) or worsening of it was observed in 42.6%. Other main complications included transient new mental disorder in 11%, temporary neurological postoperative deficits in 3.7%, bacterial meningitis in 16%, cerebrospinal fluid leaks in 8.8%. The recurrence rate was 20% and the lethality was 5.8%. CONCLUSIONS: Resection of suprasellar craniopharyngiomas using the extended endoscopic approach is a more effective and less traumatic technology, able to provide resection of the tumor along with high quality of life after surgery, and relatively rare postoperative complications and mortality.