Interhemispheric interactions analyzed by coherence during flexor spasms

Objective: We used coherence analysis to test for leading discharges on an ipsilateral right mesial temporal lesion in a 5 year old boy with flexor spasms. Method: Digital EEG analysis with video-EEG telemetry was performed preparatory to epilepsy surgery. Results: Study of 10 spasms with head drop and subsequent flexion of both arms demonstrated an interhemispheric time lag with secondary bilateral synchrony, with a mean difference of 17 ms. The right hemisphere led. After a lesionectomy with resection of epileptic regions (performed with electrocorticographical guidance), the patient has been seizure-free for 4 years. Pathology confirmed a low-grade mixed glioma and cortical dysgenesis. Conclusion: The coherence analysis demonstrated a pathway of secondary generalization, confirming that the lesional side was leading during ictal generalized discharges in flexor spasms.