Objective: The usefulness of an awake surgery for the resection of brain tumor adjacent to the eloquent area has been reported. However, during tumor resection in the supplementary motor area (SMA), intraoperative motor symptoms, which are often recognized as an unresectable region, do not necessarily indicate the permanent morbidities after the surgery. We therefore studied usefulness of the awake surgery for SMA lesions by evaluating intraoperative motor symptoms and postoperative course.
Methods: Six patients (five men, one woman, aged from 33 to 61) who underwent awake surgeries for SMA glioma were examined. During tumor resection, motor function was continuously monitored and assessed in detail. Postoperative motor function was evaluated appropriately according to each recovery process.
Results: Motor symptoms during tumor resection included delayed motor weakness, delay of movement initiation, slowness of movement, and difficulty in dual task response. Delayed motor weakness occurred later than 50 minutes from the beginning of the SMA resection. The movement initiation required 1.5 to 3 seconds after patients tried to start the movement. Moreover, the movement speed became slower (1.5 to 6.5 times) during the resection of the SMA compared with that before resection. Postoperative hemiparesis in five patients and coordination disturbances in six patients, which were observed immediately after operations, recovered to the preoperative level within 6 weeks and 12 weeks, respectively.
Discussion: In the awake surgery, even if characteristic abnormal motor responses due to the tumor resection of the SMA were observed, they do not indicate the postoperative permanent morbidities. We should recognize intraoperative SMA syndrome as postoperative reversible motor symptoms, and patients also should be informed of these particular symptoms prior to surgery. For the further utility of the awake surgery in the SMA, it would be important to differentiate positive mapping that might predict permanent deficit.