Supplementary motor area syndrome in intracranial gliomas is not associated with worse survival.

PURPOSE: Resection of gliomas involving the supplementary motor area (SMA) carries a substantial risk of postoperative functional deficits, which may affect patients' ability to undergo adjuvant therapy. This study evaluated whether postoperative SMA syndrome is associated with delayed initiation of adjuvant therapy and with progression-free survival (PFS) and overall survival (OS). METHODS: We performed a retrospective single-center study of patients undergoing resection of gliomas involving, adjacent to, or approached through the SMA between 2015 and 2024. SMA syndrome was defined as new-onset motor deficits and/or language impairment without corresponding intraoperative neuromonitoring changes and without involvement of the primary motor cortex or corticospinal tract. Logistic and Cox regression analyses were performed. RESULTS: Seventy-four patients were included, of whom 37 (50%) developed postoperative SMA syndrome. In univariate logistic regression, RANO class 2 A and class 2B resections were associated with higher odds of postoperative SMA syndrome compared with RANO class 1 resections (p = 0.048 and p = 0.035, respectively). In the pairwise multivariable model, grouped RANO class 2 resections remained associated with higher odds of postoperative SMA syndrome compared with class 1 resections (OR 5.05, 95% CI 1.24-20.57; p = 0.024). Postoperative SMA syndrome was not associated with delayed initiation of adjuvant therapy (HR 0.86, 95% CI 0.49-1.53; p = 0.617), PFS (HR 1.21, 95% CI 0.63-2.32; p = 0.573), or OS (HR 1.21, 95% CI 0.49-2.95; p = 0.681). Postoperative functional decline (≥ 20-point KPS decrease) was independently associated with receipt of modified or reduced-intensity adjuvant therapy (adjusted OR 13.91, 95% CI 2.21-87.64; p = 0.005), whereas SMA syndrome itself was not associated with treatment modification. CONCLUSIONS: Postoperative SMA syndrome was not associated with delayed adjuvant therapy or worse survival. Functional status, rather than SMA syndrome, influenced treatment intensity, supporting maximal safe resection in the SMA region.