Heart rate variability before and after seizure control in five patients with generalized seizures

Changes in heart rate variability (HRV) as a result of autonomic dysfunction has been reported in patients with epileptic seizures and this condition is associated with higher morbidity and mortality. Because most studies have been limited to cases of temporal lobe epilepsy, our study focused on cases of generalized epilepsy and examined changes in sympathetic and parasympathetic regulation. Five patients with generalized seizures were enrolled. Before seizure control and for 6 months or more after seizure control, precordial electrocardiograms were taken during an interictal period in the daytime. Frequency-domain analysis of HRV was performed using a nonparametric method of fast Fourier transformation. Each power spectrum was subsequently converted to standard frequency domain measures, including R-R interval (RR), high frequency power (HF; 0.15-0.40 Hz), low frequency power (LF; 0.04-0.15 Hz), and LF/(HF+LF) expressed in normalized units (LF%). After seizure control, there was a significant increase in HF and significant decrease in LF% relative to their levels before seizure control but no changes in RR or LF were noted. Thus, control of generalized seizures was accompanied by a simultaneous increase in parasympathetic regulation and decrease in sympathetic regulation. Our study confirms that seizure control may modulate autonomic function.