Heart rate variability during sleep in children with partial epilepsy
Ferri R, Curzi-Dascalova L, Arzimanoglou A, Bourgeois M, Beaud C, Nunes ML, Elia M, Musumeci SA, and Tripodi M (2002) Heart rate variability during sleep in children with partial epilepsy. J Sleep Res 11:2 153–60.
Abstract: Alterations in autonomic control of cardiac activity in epileptic patients have been reported by several studies in the past, and both ictal and interictal modifications of heart rate regulation have been described. Alterations of autonomic control of cardiac activity can play an important role in sudden unexplained death in patients with epilepsy (SUDEP). However, the presence of specific changes in heart rate variability (HRV) during sleep, not correlated with seizures, has not been assessed in children with epilepsy; for this reason, we evaluated features of cardiac autonomic function during sleep without ictal epileptiform electroencephalogram (EEG) activity in a group of children with partial epilepsy. Eleven patients (five males and six females; mean age 11.5 years, SD: 3.65 years) affected by partial epilepsy were admitted to this study; 11 normal subjects (five males and six females; mean age 12.9 years, SD: 2.72 years) served as a control group. All subjects slept in the laboratory for two consecutive nights. The data were analyzed during the second night. Sleep was polygraphically recorded [including one electrocardiography (ECG) channel] and signals were digitally stored. A series of 5-min ECG epochs were chosen from each sleep stage, during periods without evident ictal epileptiform activity in the EEG. Electrocardiography signals were analyzed for automatic detection of R-waves and, subsequently, a series of time- and frequency-domain measures were calculated. Epileptic subjects tended to show an overall lower HRV in both time- and frequency-domain parameters, principally during rapid eye movement (REM) sleep and, to a lesser extent, during sleep stage 2. Among the different bands, this decrease was most evident for the high-frequency band (HF) absolute power. For this reason, the ratio between the low-frequency band (LF) and HF was always higher in epileptic patients than in normal controls and the difference was statistically significant during sleep stages 3 and/or 4 and REM sleep. Our results indicate that during sleep, a particular condition of basal modification in autonomic characteristics occurs (mostly during REM sleep) in partial epilepsy patients. This finding might represent an important factor contributing to the complex mechanism of SUDEP which takes place most often during sleep and supports the need of studying HRV specifically during this state in subjects with seizures.
Keywords: autonomic function, heart rate variability, partial epilepsy, sleep, spectral analysis
Context
- Careful study from Italy using 11 children with partial epilepsy taking at least one AED as study group. HRV was lower in patients, especially during REM and stage 2 sleep. The authors contend that vagal influences are the main contributor to high-frequency variation while low-frequency variation is sympathetic or sympathetic plus vagal. They refer to many articles regarding low HRV during sleep in patients at risk for SIDS. RR interval measurement was automated and not corrected. Differences are most clear when the authors undertake spectral analyses comparing a lower frequency band, 0.04- 0.15 Hz, with a higher frequency band, 0.15-0.4 Hz. The precise significance of these bands is hard to determine.