Motor evoked potentials monitoring in resection of infratentorial lesions

Resection of infratentorial tumors is one of the most complicated surgical interventions in neurosurgery. These operations require high-quality technical equipment and high skill of the surgeon. The greatest challenge is the manipulation in the limited area with a high density of functional structures and anatomy changed by a tumor. As a result, the risk of new neurological deficits is high and can lead to a disability of the patient. The use of intraoperative neurophysiological monitoring allows a significant risk reduction of surgery. This technique allows the neurosurgeon to identify all functionally important structures in the area of surgical intervention and provides control of their functions intraoperatively in real time. Transcranial motor evoked potentials are the modality of intraoperative monitoring, a record of the motor evoked potentials in response to transcranial electrical stimulation. The method assesses the integrity of corticospinal and corticobulbar pathways, since these are the main motor pathways of the central nervous system, their damage may lead to a significant motor deficit.This article presents a review and an analysis of the literature within the historical context, which shows the development of motor evoked potentials in neurosurgery, especially in infratentorial surgery. The methodology of the transcranial motor evoked potentials and corticobulbar evoked potentials and evaluation criteria during surgery for infratentorial lesions are described. Moreover, we compared the literature data with our own experience

The impact of extent of resection in surgical outcome of pilomyxoid astrocytoma: a case study

The pilomyxoid astrocytoma (PMA) is a rare glioma that has recently been identified as a separate entity and is frequently found in the hypothalamic region. PMA is a subtype of pilocytic astrocytoma (PA), with clinical, histological, and molecular data indicating a close relationship as well as more aggressive biological behaviour in the former. There is still doubt in surgical outcome of PMA that the extent of resection, independent of location or age, is a key factor of recurrence and subsequent therapeutic choices. However, further study is needed to better understand its behaviour and, as a result, establish a consensus on its management. This research features a 2-year-6-month-old female who sought medical attention after complaining of weight loss for four weeks and vomiting for two weeks prior to her visit to the doctor. She had no additional symptoms. Only bilateral pailledema was found during the physical examination. The magnetic resonance imaging (MRI) scans revealed a tumor in the sellar area with heterogeneous enhancement. The patient had ventriculoperitoneal (VP) shunting followed by partial tumor excision twice (Extent of resection 35 percent followed by 16 percent as total 51 percent). The histology and immunohistochemical investigations revealed typical PMA characteristics. Adjuvant treatment, which included chemotherapy and radiosurgery, was initiated for the patient. She has been asymptomatic for two years and has showed no indications of progression of the disease on follow-up scans

Recurrence rate of sphenoid wing meningiomas and role of peritumoural brain edema: a single center retrospective study

Objective: To evaluate the recurrence rate of the operatively treated sphenoid wing meningiomas (SWMs) in relation to other factors and role of PTBE in recurrence as a prognostic factors in a series of 67 patients. Materials and methods: The magnetic resonance imaging (MRI), and pathology data for 67 patients with SWM, who underwent surgery at Uzhhorod Regional Neurosurgical Center between 2007 and 2021 were examined. The recurrence rate and role of PTBE in recurrence in relation to: gender, age, extend of resection, histopathology, tumor volume, location and time of recurrence were evaluated. Follow-up period ranged from 6 to 168 months (median, 87 months) after surgical resection. Results: In our study, the mean age of patients is 47 years, ranged (20-74), at the average (53.5). Male 16 (23.9%), female 51 (76.1%). Mean tumor volume was (32.8cm3), ranged 4.2cm3-143.7cm3. Edema Index (EI) 1; 27 (40.3%) absent edema, and (EI) >1; in 40 (59.7%) present edema. Recurrence rate was 11 (16.4%) patients, 8 (20.0%) patients with PTBE, as compared to 3 (11.1%) patients without PTBE, (p=0,50). Female (8 patients, 15.7%), male (3 patients, 18.7%). The mean age of recurrence was 50.9 years, ranged (21-75), at the average 52.0 years. The mean age in female was 50.8 years, in male 51.0. Bivariate analysis of simultaneous effect of gender and age on SWM recurrence with logistic regression yield both main effect and interaction effect (β gender=M=7.56±6.44, P=0.24; β age=-0.034±0.031, p=0.28; β interaction term=-0.13±0.12, p=0.26). Out of 11 recurrence cases, (2 cases, 9.5%) with small tumour volume, (5 cases, 15.6%) with medium, (3 cases, 33.3%) with large, and (one case, 20.0%) with giant tumour volume. The effect of tumour volume on recurrence rate is insignificant, χ2=2.42, p=0.49.Location of SWM; the recurrence was in (6 cases, 25.0%) of CM location, (2 cases, 25.0%) of SOM and (3 cases, 11.5%) in lateral SWM, (p=0.19). Pathological grade, in the low grade (Gr.I) 7 recurrence cases (13.0%), as compared to 4cases (44.4%) in atypical Gr II, (p=0.01). Simpson grade, the recurrence rate was; 0% in Gr. I; 13.9% in Gr. II; 20.0% in Gr.III; and 33.3% in Gr. IV and 3 cases had died in the early post op (p<0.05). Conclusion: The factors which had a strong impact on the recurrence rate in our study,; i) pathological grade (Gr. II, atypical type) p=0.01 and ii) Simpson grade (extend of tumor resection, p<0.05), while, PTBE (P=0.50), tumor volume (χ2=2.42, p=0.49) and location (χ2=3.37, p=0.19), are weak and non strong factors for recurrence. However, time of recurrence is shorter in patients with PTBE (W=20.5, p=0.092). WHO Gr. II (Spearman’s p=-0.86, p=0.00063) and negligible for Simpson grade (Spearman’s=-0.15, p=0.66)

Динамика болевого синдрома у пациентов с остеопоротическими вертебральными переломами: анализ результатов 27 операций баллонной кифопластики

Вступление. При остеопорозе высок риск возникновения вертебральных переломов, значительно ухудшающих качество жизни пациентов. В первую очередь это обусловлено стойким болевым синдромом. Цель: Изучить динамику болевого синдрома и социальной адаптированности пациентов, оперированных по поводу компрессионных переломов позвоночника на фоне остеопороза с применением чрескожной баллонной кифопластики. Материалы и методы. Проанализированы результаты лечения 27 больных с неосложнёнными переломами грудопоясничного отдела позвоночника на фоне остеопороза. В 31 % случаев имела место двухуровневая компрессия, в 69 % – одноуровневая. Унипедикулярный доступ выполнен у 8 пациентов, а бипедикулярный – у 19 пациентов. Для оценки результатов операции использовались опросники McGill и Oswestry. Результаты. Клинически значимых осложнений не было. Все пациенты показали уменьшение интенсивности болевого синдрома и большую социальную адаптированность. Наиболее ярко эта динамика прослеживалась в первые сутки после операции. Выводы. Применение баллонной кифопластики позволяет снизить болевой синдром и улучшить социальную адаптацию пациентов

Low-frequency noise in nFinFETs of different dimensions processed in strained and non-strained SOI wafers

The results of low-frequency noise investigation in fully-depleted (FD) nFinFETs of Weff = 0.02 to 9.87 µm, Leff = 0.06 to 9.9 µm, processed on standard (SOI) and strained (sSOI) wafers are presented. It is shown that the McWhorter noise is typical at zero back gate voltage for the devices studied and the density of the corresponding noisy traps in the SiO₂ portion of the gate oxide is, as a rule, much higher than that in the HfO2 portion. The results on the McWhorter noise are used for studying the behavior of the electron mobility µ and the free electron density NS in the channel at V* ≥ 0.4 V where V* is the gate overdrive voltage. It is also shown that the Linear Kink Effect (LKE) Lorentzians appear in the low-frequency noise spectra at an accumulation back gate voltage and that the parameters of those Lorentzians are different for the sSOI and SOI nFinFETs. This is the first observation of the LKE noise under a back-gate accumulation bias for sufficiently wide nMuGFET

ВІддаленІ наслідкИ хірургічнОгО лікуваннЯ менінгіом. АналіЗ 110 ВипадкіВ

Менінгіома є найчастішою інтракраніальною пухлиною у дорослих. Часто епілепсія є основним клінічним проявом менінгіоми. Хірургічне лікування є методом вибору у пацієнтів з вперше діагностованими менінгіомами. Ранній результати операції та вплив операцій на симптоматичну епілепсію добре вивчені. Однак віддалені результати малодосліджені.Мета дослідження. Оцінити віддалені результати хірургічного лікування супратенторіальних менінгіом головного мозку та провести їх порівняння із ранніми. Дослідити динаміку симптоматичної епілепсії у цих пацієнтів.Матеріали та методи: Проведено ретроспективний аналіз перебігу захворювання у 110 пацієнтів із тотально видаленою супратенторіальною менінгіомою головного мозку. Оцінено віддалені результати ефективності хірургічного лікування. Середня тривалість спостереження становила 48 місяців (13-83).Результати: Неврологічний дефіцит в доопераційному періоді спостерігався у 50 пацієнтів; на момент виписки у 40, при оцінці в віддаленому період - у 12, з 36 оцінених. У двох пацієнтів мала місце гематома ложа видаленої пухлини. Післяопераційна летальність становила 1,8 % - два пацієнти із судинними ускладненнями. 30 із 40 пацієнтів, які мали епілепсію до операції стали вільними від нападів після втручання. У 10 з 40 пацієнтів епілепсія зберігалася.. В тому числі у 2-х пацієнтів через продовжений ріст менінгіоми. У 7 пацієнтів із 70, які не мали нападів до операції, виникли напади у ранньому та/або пізньому післяопераційному періоді з різних причин. 87 (79 %) пухлин були вискодиференційованими, анапластична менінігіома виявлена у 5 (4,5 %) пацієнтів.Висновок: Тотальне видалення менінгіоми дозволяє досягнути хороших віддалених результатів. В нашій серії випадків неврологічний дефіцит при тривалому спостереженні зберігся тільки у 12 (11 %) з 50 (45,4 %) пацієнтів, які мали його до операції. Симптоматична епілепсія регресувала у 75 % пацієнтів. Відмічалася поява нападів у 7 пацієнтів з 70 в кого епінападу до операції не спостерігалися. Гістологічно у 87 (79 %) пацієнтів була виявлена Grade І менінгіом

METHOD OF AUDITORY EVOKED POTENTIALS IN THE SURGICAL TREATMENT OF CEREBELLOPONTINE ANGLE TUMORS

This article presents a review of literature on cerebellopontine angle tumors, anatomy and physiology of the vestibular nerve, intraoperative neurophysiological monitoring and method of registration of auditory evoked potentials. In view of the development of neurosurgical equipment in our time, it becomes possible to perform surgical interventions while maintaining functionally significant structures and thus improving the patient's quality of life in the postoperative period. The aim of the study – to demonstrate the effectiveness of the use and the method of intraoperative neurophysiological monitoring in the modality of the auditory evoked potentials aimed at preserving the function of cochlear nerve during surgery on the cerebellopontine angle tumors. The object of the study is the function of the cochlear nerve, and the subject of the study is the auditory evoked potentials. Materials and Methods. The Auditory Evoked Potentials reflect the entire sensitive path of the vestibulocochlear nerve. Using Medtronic Xomed NIM-Eclipse intraoperative neuromonitoring system with 32-channel neurophysiological unit was performed. The impulses move through the conductive path of the auditory analyzer: the first auditory neuron – bipolar cells – spiral ganglion, second neuron – ventral and dorsal nuclei at the lateral angle of the rhomboid fossa, third auditory neuron – the lower lobes of the corpora quadrigemina, fourth auditory neuron is – the medial geniculate bodies – Heschl gyrus. On the monitor screen, we get seven waves designated by the Roman numerals I, II, III, IV, V, VI, VII. The evaluation of the data of the amplitude and latency of all the waves makes it possible to analyze the functional integrity of the leading hearing path at all its levels. With this method, the neurosurgeon gets the information on the functional status of the nerve. Results and Discussion. In total, 35 (100 %) patients with cerebellopontine angle tumors underwent surgical operations in the Uzhhorod Regional Clinical Center of Neurosurgery and Neurology during the period dating from February 2016 till August 2017. Among them, 30 (85.7 %) patients lost the hearing at the preoperative stage; 5 (14.2 %) patients had subnormal hearing preserved on the affected side. The auditory evoked potentials were not registered before the beginning of the main stage in the group of patients, who lost the hearing at the preoperative stage, and the predominant diameter of the tumor was more than 25 mm. As for the patients with preserved hearing, the diameter of the tumor was less than 25 mm. Conclusions. The correlation between the clinical signs at the preoperative stage (preserved hearing) and tumor size was determined. The use of this method for treating cerebellopontine angle tumors up to 25 mm in diameter is effective