Features of intraoperative neuromonitoring of the supplementary motor area of the brain. Literature review and case report

Abstract

Introduction. Supplementary motor area (SMA) syndrome is a symptom complex resulting from damage to the premotor cortex and it’s subcortical projection. There is no generally accepted protocol for functional mapping of SMA during neurosurgical intervention in this area.The objective of the publication is to present a review of the literature and clinical cases from practice that describes the treatment of two patients with glioblastomas in the posterior regions of the superior frontal gyrus with IOM. Given the localization of the tumor in the dominant hemisphere, one operation was performed with awakening, the other according to the protocol of total intravenous anesthesia with mapping of only motor representative areas.Clinical cases. In both cases, during intraoperative direct electrical stimulation of the cortex subjected to resection, evoked motor responses were not recorded. The modalities used made it possible to continuously evaluate the viability of the cortico‑spinal tract. During the surgery with awakening, episodes of an instantaneous termination of the initia‑ tion of speech and counter directional movements in the arm were recorded – in the subcortical projection of the SMA at a current strength of 1–2 mA. Both patients in the early postoperative period showed the development of a gross transient neurological deficit in the form of hemiparesis and sensorimotor aphasia, which was a manifestation of pos‑ tresection SMA syndrome. During the follow‑up (control) examination 6–7 months after the operation, the following was observed in the clinical picture: mild hemiparesis up to 4–5 points, impaired bimanual coordination; difficulty the ini‑ tiation of speech spontaneous speech.Conclusion. When mapping the cortex and subcortical structures, the localization of SMA can be assumed in the event of a negative motor response of the cerebral cortex using the protocol of low‑frequency 1 Hz stimulation under EcoG control. Standardization of the SMA mapping protocol would be useful in clinical practice for determining the bounda