SURG-19. THE SYNDROME OF THE SUPPLEMENTARY MOTOR AREA: CLINICAL COURSE AND PREDICTORS OF OUTCOME AFTER RESECTION OF PREMOTOR LESIONS

Abstract OBJECTIVE Supplementary motor area (SMA) syndrome frequently occurs after resection of premotor lesions. Interhemispheric connectivity including the contralateral SMA might be crucially involved in its development and recovery. We aimed to identify predictors of outcome by quantifying preoperative structural alterations in the non-affected contralateral hemisphere. METHODS We retrospectively searched our database for patients developing SMA syndrome after resection of premotor lesions between 2013 and 2023. Clinical characteristics and imaging data were collected. Structural network analysis was performed using the previously validated morphometric inverse divergence network. RESULTS 27 patients with a mean age of 39.2 ± 17.7 years developed SMA syndrome, including 13/27 patients (48.1%) with primary brain tumors and 14/27 patients (51.9%) with intractable lesional epilepsy. Postoperative SMA syndrome was commonly characterized by contralateral upper extremity hemiparesis (19/27 patients, 70.4%) and aphasia in case of dominant hemisphere involvement (13/13 patients, 100%). Tumor patients were less likely to fully recover from SMA syndrome after 7 days compared to epilepsy patients (2/13 [15.4%] versus 9/14 [64.3%] patients, p=0.018). Most patients (23/27, 85.2%) experienced full recovery of SMA syndrome after a median follow-up of 5 months (IR 3-16 months), with no difference between patients with tumors or epilepsy (p=0.999). Preoperative contralateral intra-hemispheric connectivity was similar between patients receiving tumor or focal resection (0.183 vs 0.177, p=0.295). However, imaging analyses demonstrated baseline affection of SMA connectivity in patients with brain tumors as characterized by reduced cortical thickness of the contralateral frontal lobe and the cingulate gyrus compared to epilepsy patients. CONCLUSION While full recovery from SMA syndrome is common, SMA syndrome is frequently less severe and more transient in patients with epilepsy. This might be due to affection of the contralateral SMA network in tumor patients due to the infiltrative nature of the disease. Imaging analyses might assist in identifying network affections at baseline.