Risk factors for intraoperative seizures during asleep motor evoked potential monitoring in supratentorial surgery.

OBJECTIVE

Intraoperative-seizures(IOS) following direct electrical stimulation(DES) affects intraoperative neurophysiological monitoring(IONM) and may lead to stop surgical resection. We analyzed IOS risk factors during asleep brain surgery.

METHODS

We reviewed 232 consecutive patients who underwent surgery for supratentorial brain lesions with IONM, that consisted in motor evoked potentials monitoring and mapping, elicited by DES using the train-of-five technique. Preoperative history of seizures, paresis, use of anti-seizure medications(ASM), stimulated cortical regions, histology, and motor performance were evaluated. IOS was defined as clinical seizure or an after-discharge.

RESULTS

IOS occurred in 35 patients (15.1 %). IOS risk increased with higher stimulation intensities, younger age, cavernomas, and a history of seizures, especially in patients without ASM at the time of surgery. IOS did not significantly impact the extent of resection or clinical outcome, but prolonged hospital stays.

CONCLUSION

Our findings suggest that lower stimulation intensities are advisable when operating on patients with specific risk factors for IOS.

SIGNIFICANCE: We observed a significant increase in IOS risk with stimulation above 20 mA, thresholds being lower in high-risk patients. Tailored stimulation can reduce the risk of IOS. This study presents a large series on IOS risk factors during asleep surgeries and provides a review of these factors.