Effects of anterior thalamic nucleus DBS on interictal heart rate variability in patients with refractory epilepsy

Abstract

Objective: Heart rate variability (HRV) changes were investigated by several studies after resective epilepsy surgery/vagus nerve stimulation. We examined anterior thalamic nucleus (ANT)-deep brain stimulation (DBS) effects on HRV parameters.

Methods: We retrospectively analyzed 30 drug-resistant epilepsy patients' medical record data and collected electrocardiographic epochs recorded during video- electroencephalography monitoring sessions while awake and during N1- or N2-stage sleep pre-DBS implantation surgery, post-surgery but pre-stimulation, and after stimulation began.

Results: The mean square root of the mean squared differences between successive RR intervals and RR interval standard deviation values differed significantly (p < 0.05) among time-points, showing increased HRV post-surgery. High (0.15-0.4 Hz) and very low frequency (<0.04 Hz) increased, while low frequency (0.04-0.15 Hz) and the LF/HF ratio while awake decreased, suggesting improved autonomic regulation post-surgery. Change of effect size was larger in patients where both activated contacts were located in the ANT than in those where only one or none of the contacts hit the ANT.

Conclusions: In patients with drug-resistant epilepsy, ANT-DBS might positively influence autonomic regulation, as reflected by increased HRV.

Significance: To gain a more comprehensive outcome estimation after DBS implantation, we suggest including HRV measures with seizure count in the post-surgery follow-up protocol.

Keywords: Deep brain stimulation; Drug-resistant; Epilepsy; Heart rate variability; Thalamus.