Epileptic seizures developing for the first time after a neurosurgical intervention (de novo seizures) are a challenge for choosing an optimal treatment. The pathogenesis of these seizures is often associated with factors that become inactive in the early postoperative period. These seizures can not serve the basis for diagnosing symptomatic epilepsy and should be regarded as a brain response to surgery, and patients do not need anticonvulsant therapy that reduces the quality of life. But in some situations, new early postoperative seizures serve the onset of symptomatic epilepsy and require prolonged anticonvulsant therapy. To date, one of the main techniques to identify the nature of newly developed seizure and to plan further treatment (whether or not to use anticonvulsant therapy) is video EEG monitoring. We present two clinical cases of patients who developed de novo convulsive seizures in the early postoperative period in similar situations after resection of intracerebral tumors. The use of video EEG monitoring allowed avoiding unreasonable use of anticonvulsant therapy in one of the patients.

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BACKGROUND: Intraoperative neurophysiological monitoring is an obligatory tool during fossa posterior surgery. Corticobulbar motor evoked potentials is the modality of intraoperative neurophysiological monitoring, which can be used during such neurosurgery interventions. It is used to determine the functional state of the caudal cranial nerves during surgery. However, there are technical features of this modality, therefore, corticobulbar motor evoked potentials are not used routine in neurosurgery now. AIM: To establish the predictive value of corticobulbar motor evoked potentials for development of dysphagia after removal of tumors of brainstem and fourth ventricle. MATERIALS AND METHODS: We analyzed 80 patients aged from 11 months to 67 years. In 49 cases tumor located in forth ventricle (34 adults and 15 children). In 31 cases tumor located in upper brainstem and craniospinal region (16 adults and 15 children). All patients underwent neurosurgery removal of tumor with intraoperative neurophysiological monitoring. We analyzed otoneurological symptoms before and after operation, MR-images, the volume of removed tumor was estimated. We analyzed data of intraoperative neurophysiological monitoring; the main modality of intraoperative neurophysiological monitoring was corticobulbar motor evoked potentials. RESULTS: Progress in neurological symptoms from caudal nerves was observed in 35% cases. Amplitude of corticobulbar motor evoked potentials statistically depends on neurological symptoms from caudal nerves in early postoperative period. When the amplitude of the corticobulbar motor evoked potentials decreases by more than 34% from the initial level, there is a high probability of appearance or increase of symptoms from the caudal group of cranial nerves after surgery. The sensitivity and specificity of the corticobulbar motor evoked potentails are 94.4 and 89.2%, respectively. CONCLUSIONS: It is necessary to use the corticobulbar motor evoked potentials to determine the functional state of the caudal group of cranial nerves during brainstem and forth ventricle surgery and to predict the development of dysphagia and dysarthria after surgery. The modality has a high prognostic value both in children and in adults.

Introduction. Corticobulbar motor evoked potentials (CB-MEP) are a modality of intraoperative monitoring (IOM) for assessment of the functional state of caudal cranial nerves. CB-MEPs can be used during fossa posterior surgery, when there is a risk of damaging the caudal cranial nerves and their nuclei. The possibility of using this modality in pediatric patients is rarely discussed in the literature. Objective. To assess the CB-MEP validity in the prognosis of neurological symptoms from caudal cranial nerves in the pediatric group of patients after surgery in the brainstem and fourth ventricle. Material and methods. The study included 30 children aged from 11 months to 17 years who underwent brainstem and the fourth ventricle tumor surgery with IOM at the N.N. Burdenko National Medical Research Center for Neurosurgery from January 2020 to November 2021. Results. We obtained statistically significant difference in the dynamics of the CB-MEP amplitude in the groups of patients with and without an increase in neurological symptoms (p<0.05). Conclusion. CB-MEP can be used during brainstem surgery in pediatric patients for assessing the functional state of caudal cranial nerves.

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