The Value of Postictal Electroencephalogram in Temporal Lobe Seizures

Abstract

Background: The ictal changes on scalp electroencephalogram (EEG) helps in lateralizing and localizing the seizure origin, however, the value of postictal EEG has received limited study. Objectives: To examine the value of postictal EEG in simple partial (SP), complex partial (CP), and secondary generalized (SG) temporal lobe seizures. Methods: Patients with detailed Video EEG monitoring who were seizure free for a minimum of 2 years following a temporal lobectomy were identified. Up to 3 seizures per patient were classified as SP, CP, or SG based on the patient description and video-tape review. The ictal EEGs were masked and the postictal EEG segments were randomly reviewed by one electroencephalographer (EEGer), who was blind to all clinical and EEG data. He assigned each segment to unilateral, bilateral, or no postictal delta activity (PDA). Results: 53 seizures and accompanying EEGs from 20 patients were studied. The age at temporal lobectomy ranged between 19-45 years (mean 29.5). Pathology revealed mesial temporal sclerosis in 16 (80%). PDA was identified in 55%, 85%, and 100% of postictal EEG segments of SP, CP, and SG seizures respectively. Unilateral PDA was identified in 36%, 76%, and 44% of postictal EEG segments of SP, CP, and SG seizures respectively. Unilateral PDA was ipsilateral to the side of surgery in 94% of EEGs. Conclusion: The postictal EEG may be helpful in the identification and lateralization of all types of seizures originating from the temporal lobe.