Object: Supplementary motor area (SMA) resection often induces postoperative contralateral hemiparesis or speech disturbance. This study was performed to assess the neurological impairments that often follow SMA resection and to assess the risk factors associated with these postoperative deficits.
Methods: The records for patients who had undergone SMA resection for pharmacologically intractable epilepsy between 1994 and 2010 were gleaned from an epilepsy surgery database and retrospectively reviewed in this study.
Results: Forty-three patients with pharmacologically intractable epilepsy underwent SMA resection with intraoperative cortical stimulation and mapping while under awake anesthesia. The mean patient age was 31.7 years (range 15-63 years), and the mean duration and frequency of seizures were 10.4 years (range 0.1-30 years) and 14.6 per month (range 0.1-150 per month), respectively. Pathological examination of the brain revealed cortical dysplasia in 18 patients (41.9%), tumors in 16 patients (37.2%), and other lesions in 9 patients (20.9%). The mean duration of the follow-up period was 84.0 months (range 24-169 months). After SMA resection, 23 patients (53.5%) experienced neurological deficits. Three patients (7.0%) experienced permanent deficits, and 20 (46.5%) experienced symptoms that were transient. All permanent deficits involved contralateral weakness, whereas the transient symptoms patients experienced were varied, including contralateral weaknesses in 15, apraxia in 1, sensory disturbances in 1, and dysphasia in 6. Thirteen patients recovered completely within 1 month. Univariate analysis revealed that resection of the SMA proper, a shorter lifetime seizure history (<10 years), and resection of the cingulate gyrus in addition to the SMA were associated with the development of neurological deficits (p=0.078, 0.069, and 0.023, respectively). Cingulate gyrus resection was the only risk factor identified on multivariate analysis (p=0.027, OR 6.530, 95% CI 1.234-34.562).
Conclusions: Resection of the cingulate gyrus in addition to the SMA was significantly associated with the development of postoperative neurological impairment.