Abruptly attenuated terminal ictal pattern in pediatrics

Purpose: We examined the ictal discharges at the end of pediatric seizures and categorized the various patterns. One particular pattern, termed "abruptly attenuated termination" was studied in detail. Methods: Ictal segments captured on video-EEG monitoring during a 26-month interval were analyzed for a variety of ictal termination patterns, including one that we rigorously defined as abruptly attenuated termination pattern (AAT). We studied the associations between AAT and the other ictal EEG and clinical features. Results: AAT was noted in 16 of 200 (8%) pediatric seizures. All 16 were immediately preceded by repetitive spikes or spike-waves. The presence of AAT also correlated with ictal spread pattern, initial ictal pattern, laterality of onset, seizure duration, age, and epilepsy etiology. AAT is more often noted in children older than 6 months and in children with idiopathic or cryptogenic forms of epilepsy. Conclusions: The minority of pediatric seizures recorded in a tertiary epilepsy monitoring unit end with diffuse, synchronized abrupt attenuation. AAT probably is the result of an active process that is developmentally related. It appears to require some degree of mature and intact neurophysiology and may involve the thalamocortical circuit.