Search

We present clinical observation of a 3-year-old child during recovery after acute hypoxic brain injury (freshwater drowning). Using diagnostic transcranial magnetic stimulation and magnetic resonance tractography with reconstruction of the corticospinal tract (CST) originated from the primary motor cortex and supplementary motor area (SMA), we determined that hypoxic brain injury induced activation of CST from the SMA. The period of reorganization was associated with the development of epileptiform patterns, that confirms the transient hyperexcitability of cortical neurons. Our findings indicate no recovery of motor function after acute hypoxic brain injury when CST originated only from SMA.

Preoperative planning on the basis of combined data of navigated transcranial magnetic stimulation and MR-tractography give an opportunity to choose an optimal treatment approach in each clinical case. There were performed the examinations in 52 patients with tumors situated in projection of central gyrus. The neurosurgical interference was admitted as inappropriate in 3 (5,8%) patients. The volume of planned operation was reduced in 14 (26,9%) cases. The examination of 15 (28,9%) patients allowed choice of the correct access trajectory. The navigated transcranial magnetic stimulation assisted in performance of more safe removal of neoplasms closed to the functionally meaningful zones of the brain in 20 (38,4%).

Background: Tumors of the paralimbic system were considered inoperable for a long time due to high risk of postoperative complications. However, there have been significant changes in surgical tactics for these neoplasms over the past decades. Despite the improvement of surgical principles for these tumors and development of new approaches, risks of surgical treatment are still high (up to 33.6%)., Objective: To assess the results of surgical treatment of paralimbic glial tumors and identify predictors of adverse outcomes., Material and Methods: We retrospectively analyzed postoperative outcomes in 52 patients with paralimbic glial tumors at the neurosurgical department of the Pirogov National Medical Surgical Center between 2016 and 2020. Tumor dimensions and topography with surrounding structures were evaluated using preoperative MRI. Resection quality was evaluated within the first postoperative day considering MRI data. We applied transcranial or transcortical electrostimulation, direct cortical and subcortical bi- and monopolar stimulation for intraoperative functional assessment of corticospinal tract. Neurological examination was performed prior to surgery, after 24 hours, 7 days, and 6 months., Results: Total resection was performed in 39 patients, almost total - 5 patients, subtotal - 6 patients, partial resection - 2 patients. Mean volume of tumors before surgery was 95.1±55.1 cm 3 . After surgery, volume ranged from 0 to 24.7 cm 3 (mean 2.2±5.01 cm 3 ). After 24 hours, neurological symptoms de novo or aggravation of preoperative motor deficit was revealed in 17 (33%) patients. However, this impairment regressed in most patients, and only 4 (7%) patients retained these disorders after 6 months., Conclusion: Transcortical or combined surgical approach in conjunction with multimodal neurophysiological monitoring allows total or close to total resection of paralimbic glioma in 85% of cases. Risk of postoperative complications is 7%. Unfavorable prognostic factors of neurological impairment are decrease in muscle response amplitude ≥50% according to transcranial neurophysiological stimulation and tumor spread medial to perforator arteries.

Objective: To compare monopolar and bipolar mapping in point-by-point fashion by using of threshold amperage, frequency of positive motor responses and the number of muscles involved in response., Material and Methods: A prospective non-randomized study included 14 patients with supratentorial tumors who underwent surgery in 2018-2019. All neoplasms were localized within 2 cm from the motor cortex and pyramidal tract. Age of patients ranged from 25 to 74 years. There were 9 women and 5 men. Eight patients had malignant glioma (grade III - 4, grade IV - 4), 6 patients - meningioma. Motor functions were assessed in all patients before and after surgery (1, 7 days and 3 months later) by using of a 5-point scale. In addition to routine neurophysiological monitoring, comparative mono- and bipolar mapping of the pyramidal tract within the bed of excised tumor was carried out at the end of surgery. The points of motor responses were marked. Comparative analysis of mono- and bipolar stimulation at identical points included threshold amperage, frequency of positive motor responses and the number of muscles involved in response (leg, forearm, hand, facial muscles). Brain MRI was performed in early postoperative period for assessment of resection quality., Results: There were 64 points of motor responses in 14 patients. The number of these points ranged from 2 to 8 per a patient (mean 5 points). Motor responses were recorded in 57 points during monopolar and bipolar stimulation, in other 7 points - only during monopolar stimulation. Amperage of monopolar stimulation was 3-15 mA, bipolar stimulation - 2.5-25 mA. Threshold amperage (7.37 mA for monopolar stimulation and 8.88 mA for bipolar stimulation; p =0.12), frequency of positive motor responses and the number of muscles involved in response ( p =0.1 and p =0.73) were similar. Seven (50%) patients had neurological deterioration in early postoperative period (4 patients with glial tumors and 3 patients with meningiomas). At the same time, only 2 patients (14.3%) had persistent neurological deficit (both patients with infiltrative meningioma). According to postoperative MRI in T1+C mode, resection volume was 100% in 1 patient with contrast-enhanced glioma and 94% in another one. According to FLAIR MRI data, resection volume exceeded 70% in 2 patients with non-enhancing glioma and less than 70% in 2 patients. Meningioma resection volume was estimated according to postoperative T1+C MRI data and made up over 90% in 4 patients., Conclusion: Monopolar stimulation is a reliable method of pyramidal tract identification in supratentorial brain tumor surgery.