INTRACRANIAL EEG SEIZURE-OFFSET TERMINATION PATTERNS - RELATION TO OUTCOME OF EPILEPSY SURGERY IN TEMPORAL-LOBE EPILEPSY

Purpose: Studies using stereo-EEG (SEEG) and electrocorticography (ECo G) should not only identify a patient's epileptogenic zone, but also s hould provide prognostic information for surgical outcome. In this res pect, seizure-offset patterns have so far been the subject of only one study, in which they were shown to be associated with poor outcome wh en recorded over cortical areas outside the temporal lobe of seizure o nset. To clarify whether seizure-offset patterns are reliable in predi cting seizure outcome, we studied SEEG/ECoG in a similar group of pati ents with temporal lobe epilepsy (TLE). Methods: SEEG/ECoG records of 44 patients with refractory TLE were analyzed. The areas of seizure te rmination were classified as ipsilateral or contralateral (mesial and/ or lateral) temporal, (temporal and) frontal, and diffuse/bilateral. P atients were classified with respect to seizure outcome as either seiz ure-free (UCLA class 1a) or not seizure free (UCLA class 2-4); both gr oups were correlated with specific seizure-offset categories using Fis her's exact probability test and analysis of variance (ANOVA). Results : Of the 44 patients, the majority (n = 36) had at least part of their seizure offsets in the ipsilateral temporal lobe, whereas 8 patients manifested no seizure offsets in this lobe. Only 9 patients (20%) show ed exclusive offsets in the ipsilateral temporal lobe. No statisticall y significant difference was evident between patients with all seizure offsets in the ipsilateral temporal lobe and those with offsets elsew here. Similarly, no statistically significant difference was evident b etween patients with a diffuse seizure offset and those with seizure o ffsets of a different category. Conclusions: Seizure-offset patterns i n SEEG/ECoG are unreliable in predicting seizure outcome after resecti ve activity surgery for TLE.