SURG-17. COMBINED AWAKE CRANIOTOMY AND TRANSCORTICAL MEP FOR RESECTION OF MOTOR AREA GLIOMAS

Abstract

BACKGROUND: Resection of primary motor area gliomas have risk of severe motor deficits and it is considered difficult to massive removal. We have actively resected gliomas in this area with combined awake craniotomy and transcortical motor evoked potentials (MEP) since 2005. We presented the removal method and surgical results for tumor in this area, and examined factors related to postoperative motor deficits. METHODS: The present study included 30 consecutive patients (nine men and nine women; mean age 40 years) with a primary motor area glioma from 2005 to 2017. All tumors were removed with confirming spontaneous movement during awake craniotomy and monitoring transcortical MEP. Postoperative motor deficits were evaluated in four categories: Stable, Declined (Mild, Moderate, Severe). We defined Moderate and Severe as deficits that interfere with daily life. RESULTS: In 28 of 30 cases, an effective waveform was not obtained with transcortical MEP. The mean extent of resection was 93%. Motor deficits at 6 months after surgery were Stable 20, Mild 7, Moderate 2 cases, and Severe one case. Moderate and Severe deficits were confirmed in 3/30 cases (10%). Motor deficits at 6 months after surgery was significantly correlated with declined intraoperative spontaneous movement, decreased transcortical MEP more than 50%, and presence of ischemic lesion postoperative MRI. The patients without declined spontaneous movement with/without decreased transcortical MEP showed no decline of motor function 6 months after surgery (6 patients). While, those with declined spontaneous movement without decreased transcortical MEP showed 20% (2 of 10 patients) of declined cases, and those with declined spontaneous movement with decreased transcortical MEP more than 50%, 67% (8 of 12 patients) of declined cases. CONCLUSIONS: Monitoring of spontaneous movement during awake craniotomy and neurophysiological monitoring by transcortical MEP have complementary relationship, are useful for removal of primary motor area gliomas, and contribute aggressive removal.