Surgical treatment of lesions involving the supplementary motor area: clinical results of 12 patients

Surgical resection of lesions involving the dominant supplementary motor area (SMA) may result in immediate postoperative motor and speech deficits which in most cases are reversible.We report 12 patients with frontal lesions involving the SMA and aim to analyse the clinical data and the correlation of neurological deficit with the extent of SMA resection. 12 patients (5M/7F, mean age 30.5) harbouring lesions involving the SMA who underwent surgery between 2002-2007 were evaluated retrospectively. Eloquent cortical areas were determined by functional MRI studies and/or invasive monitoring with subdural grids and depth electrodes and/or awake craniotomy with continuous intraoperative monitoring. The evaluation of postoperative MRI's revealed total and subtotal resection of the lesion in 9(75%) and 3(25%) patients respectively. The extent of SMA resection was complete in 5 patients (41,6%) and incomplete in 7 patients (58,3%). Immediately postoperatively, all patients where the resection of SMA was complete displayed the typical characteristics of SMA syndrome. The degree of deficits was consistent with the extent of the SMA resection in all patients. Proper diagnostic methods aiming to localise the sensorimotor area can minimize the risk of deficit in the surgical treatment of SMA lesions. The results suggest a relationship between the incidence of SMA syndrome and the extent of SMA resection.