Interictal EEG as a predictor of outcome after surgery in patients with refractory temporal lobe epilepsy and hippocampal sclerosis.

Aim: To detect value of Interictal EEG in prediction of post surgical outcome in patients with hippocampal sclerosis. Methods: 24 hour awake and sleep interictal and ictal EEG data was analyzed in 60 patients with medial temporal sclerosis on MRI and histopathologically verified HS. All patients had at least 12 months follow up after surgery. Patients were grouped into those with preponderantly unilateral (> 75% of all discharges or exclusively unilateral) and those with bilateral interictal epileptiform discharges. Oligospikers were defined as those with < 1 spike/hour. Univariate analysis with odds ratio (OR) was employed in data analysis. Chi square test was used for P value. The interictal EEG findings were correlated with ictal EEG onset and outcome (favorable -- Engel's Class 1&2 and poor Classes 3-5). Results: Among 60 patients, all seizures arose from expected side in 55. Patients with bilateral spikes had poor outcome (28%) compared with unilateral spikes (5%) {OR -- 7.69(C.I. 5.94-9.44) and P < 0.001}. Unilateral interictal discharge is a predictor of ipsilateral seizure origin {OR 8.94 (C.I. 6.68-11.20). [ABSTRACT FROM AUTHOR]