Abstracts

The experience of sudden unexpected death in epilepsy (SUDEP) obliges clinicians to consider possible etiologies and investigate possible preventing mechanisms. A reduction of the heart rate variability (HRV) has been reported in several cardiological and neurological diseases (Kamath MV et al. Crit Rev Biomed Eng 1993;21:245-311) and an association between reduced HRV and sudden death has been suggested. Several studies on HRV and epilepsy provide evidence of a sympathetic/parasympathetic dysbalance. Central modulation of autonomic function was studied by spectral analysis of HRV. Subjects: 7 patients who died from SUDEP, 21 with epilepsy, 15 with psychogenic seizures, and two healthy drug free controls for each SUDEP patient matched for age and sex. Patients and controls underwent a 15 min standard electroencephalogram (EEG) with electrocardiogram (ECG)- channel. High frequency HRV (HF-HRV) was analyzed by an algorithm developed by Porges (Porges SW et al. Biol Psychol 1992;34:93-130). Twenty-one consecutive 30 second epochs of interbeat intervals were submitted to the polynomial filter providing estimates of HF-HRV. These estimates were analyzed by a repeated measure analysis of variance using epoch-number as within-subject factor and group membership as between-subject factor. Post hoc contrasts revealed that the SUDEP patients had significantly lower HF-HRV than epilepsy patients (p=.045), patients with psychogenic seizures (p=.029) and healthy controls ([lt]0.01).
Discussion: Our study provides evidence that SUDEP patients have an altered autonomic control of the heart, with a reduction in HF-HRV measures. This suggests a decreased parasympathetic tone, which may be related to drug therapy, epilepsy as such or a concomitant maturation deficit of the central autonomous network. Decreased HF-HRV may be associated with an increased risk for SUDEP.