SIGNIFICANCE OF SPIKES AT TEMPORAL-LOBE ELECTROCORTICOGRAPHY

Among 87 consecutive patients operated on under local anesthesia, few aspects of pre- and posttemporal lobe resection electrocorticograms (E CoG) yielded prognostic data. Preresection spikes were most common in the hippocampus, followed in order of frequency by the anterior tempor al convexity and the inferior temporal surface, Moderately frequent(>1 0 spikes/100 s) preresection spikes appeared beyond the subsequent res ection line in the posterior temporal region in 16 of 87 (18%) and in orbital frontal cortex in 12 of 87 (14%). Although many hippocampus sp ikes portended a favorable outcome and rare spikes an unfavorable one, preresection spike quantity otherwise failed to distinguish outcome g roups. Absolute quantity of postresection spikes and change from prere section quantity in any region did not correlate with outcome except f or the insula, where relatively abundant spikes portended favorable ou tcomes, Postresection electrographic seizures were rare but occurred e qually in all outcome groups. No significant change in spike incidence occurred between the first and last 10-min epoch of the 30-min postre section recording.