Abstracts

Rationale: We examined usefulness of ictal HFO analysis for adult patients with MRI-negative neocortical epilepsy.Methods: This study consisted of 13 adult patients with neocortical epilepsy who had MRI negative lesion and underwent curative epilepsy surgery without removal of hippocampus. FDG-PET and chronic intracranial ECoG monitoring were performed in all of 13, FMZ-PET in 11, MEG in 7, and SISCOM in 5 patients to detect epileptogenic focus. After 2013, we introduced ictal HFO analysis. We analyzed surgical procedures and outcome of patients before (group A: 8 cases) and after (group B: 5 cases) ictal HFO analysis at least 1 year after surgical intervention.Results: 1) Group A included 6 frontal lobe epilepsies (FLE), 1 lateral temporal lobe epilepsy (TLE), and 1 parietal lobe epilepsy. They underwent focus resection in 6, CCS in 3, and extensive MST in 3 cases. 2) Group B included 4 lateral TLEs and 1 FLE. They underwent focus resection in 3 and extensive MST in 2 cases. Ictal HFO analysis indicated different or narrow epileptogenic focus from visual analysis in 4 of 5 patients. Hippocampal transection was added to 3 lateral TLE patients who showed fast spread of epileptic discharge in the hippocampus. 3) In group A, 3 patients obtained Engel class II outcome, and 5 patients achieved Engel class III or IV outcome at least 7 years after surgery. In group B, 3 lateral TLE patients became Engel class I, 1 lateral TLE became Engel class II, and 1 FLE remained Engel class IV at least 1 year after surgery.Conclusions: Ictal HFO analysis of adult patients with MRI-negative neocortical epilepsy was useful method for epilepsy surgery. However, we need more long observations and accumulation of cases for reaching a firm conclusion.