Autonomic dysregulation in children with epilepsy with postictal generalized EEG suppression following generalized...

Postictal generalized electroencephalographic suppression (PGES) has been associated with sudden unexpected death in epilepsy (SUDEP) in adults. Decreased heart rate variability (HRV) is one clinical marker of SUDEP in adults with epilepsy. The objective of this study was to analyze the characteristics of HRV associated with generalized convulsive seizures (GCS) ± PGES in children.

Nine hundred and seventy-seven consecutive children who underwent prolonged scalp video-EEG (vEEG) and 1-lead electrocardiogram (ECG) monitoring at the Hospital for Sick Children, Toronto, Ontario, Canada were reviewed retrospectively from 2009 to 2011. Thirty-five children had GCS captured during their vEEG with or without PGES and met inclusion criteria. Children were subdivided into three age groups and compared with age-matched controls: 3-6 years; 7-12 years; and 13-18 years. Interictal HRV was measured at 5 min during N2 sleep. Preictal HRV was measured at 1 h prior to GCS onset, and postictal HRV was measured at 3 min post-GCS cessation. Low frequency (LF: ms², 0.04-0.15 Hz) and high frequency (HF: ms², 0.15-0.4 Hz) bands of heart rate oscillations were analyzed during the interictal and preictal periods. The root mean square of successive differences (RMSSDs) was analyzed during the following time points: interictal; preictal; and postictal.

Thirty-five children had GCS: 18 children with PGES [3-6 years (n = 2); 7-12 years (n = 6); 13-18 years (n = 10)] and 17 children without PGES [3-6 years (n = 6); 7-12 years (n = 5); 13-18 years (n = 6)]. Seventeen additional age-matched controls were identified [3-6 years (n = 3); 7-12 years (n = 5); 13-18 years (n = 9)]. Seventy-four GCS were captured consisting of 36 GCS + PGES and 38 GCS - PGES. There was no difference of interictal HRV among children with GCS ± PGES and controls. The preictal LF and HF in 36 GCS + PGES were significantly higher compared with 38 GCS - PGES (p < 0.01). The postictal RMSSD in 36 GCS + PGES was significantly higher compared with 38 GCS - PGES (p < 0.01). The pre- to postictal RMSSD change was significantly lower in children with GCS + PGES than in those with GCS - PGES (p = 0.035).

In summary, the preictal HRV in GCS + PGES was significantly higher than in children with GCS - PGES. The higher remaining postictal RMSSD in children with GCS + PGES is a potential indicator of autonomic dysregulation. In certain children with epilepsy, autonomic dysregulation may contribute to poor recovery from a GCS with subsequent PGES, thereby contributing to SUDEP. Heart rate variability and autonomic regulation in children with epilepsy should be further studied prospectively in order to better understand the mechanism by which PGES may lead to SUDEP.