Predictive Value of Electrocorticography in Patients With Mesial Temporal Lobe Epilepsy Undergoing Selective Amygdalohippocampectomy.

PURPOSE: The utility of intraoperative electrocorticography has been reported in predicting seizure outcome in patients with mesial temporal lobe epilepsy due to mesial temporal sclerosis (MTS) undergoing standard temporal lobectomy. Three studies reported the predictive outcome in patients with MTS undergoing selective amygdalohippocampectomy (sAHE). We evaluate the predictive value of the intraoperative electrocorticography in postoperative outcome in patients with mesial temporal lobe epilepsy secondary to MTS undergoing sAHE.

METHODS: Retrospective analysis of 36 consecutive patients with mesial temporal lobe epilepsy undergoing sAHE between 2001 and 2012. A single neurosurgeon performed the sAHE. Preresection and postresection spikes were recorded in all patients and interpreted by two epileptologists. Long-term postoperative seizure freedom was correlated with intraoperative electrocorticography findings.

RESULTS: Ten patients had normal brain MRI (G1), whereas 26 had MTS (G2). All patients had MTS on histopathology. Mean duration of postoperative follow-up was 21.3 and 24.4 months for G1 and G2, respectively. In G1, 4/10 (40%) had resolution of spikes after sAHE, with 2/4 (50%) seizure free at last follow-up. Spikes were persistent in 6/10 (60%), with 5/6 (83%) seizure free at last follow-up (P value = 0.5). In G2, 7/26 (27%) had postresection resolution of spikes, with 5/7 (71%) seizure free at last follow-up. Spikes were persistent in 19/26 (73%), with 13/19 (68%) seizure free at last follow-up (P value = 0.62). The difference between the two arms of G1 and G2 was statistically insignificant.

CONCLUSIONS: Postresection intraoperative electrocorticography has limited value in predicting postoperative seizure freedom in patients with mesial temporal lobe epilepsy secondary to MTS undergoing sAHE.