Autonomic Nervous System Functioning Associated with Epileptic Seizures: Analysis of Heart Rate Variability van der Kruijs SJM 1,2* , Vonck KEJ 3 , Feijs LMG 4 , Bodde NMG 1,2 , Lazeron RHC 1,5 , Carrette E 3 , Boon PAJM 1,3 , Backes WH 2,6, Jansen JFA 2,6, Aldenkamp AP 1-5 , and Cluitmans PJM 1,4 1 Epilepsy Centre Kempenhaeghe, Heeze, Netherlands 2 School for Mental Health and Neuroscience, Maastricht University, Maastricht, Netherlands 3 Reference Centre for Refractory Epilepsy, Department of Neurology, Ghent University Hospital, Ghent, Belgium 4 University of Technology, Eindhoven, the Netherlands Department of Neurology, Netherlands 5 Radiology, Maastricht University Medical Centre, Maastricht, the Netherlands 6 Maastricht University Medical Centre, Maastricht, the Netherlands * Corresponding author: van der KruijsKempenhaeghe SJM, Epilepsy Centre Kempenhaeghe, Heeze, Netherlands, Tel: +31 (0)402279502; Fax: +31 (0)402265691; E- mail: sylvie.kolfschoten@gmail.com Received date: May 27, 2014; Accepted date: June 24, 2014; Published date: June 30, 2014 Copyright: © 2014 van der Kruijs SJM, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Objective: Little is known about the (peri-) ictal changes in autonomic nervous system activity of epileptic seizures. Such information may be useful for seizure prediction paradigms and differential diagnosis between epilepsy and psychogenic non-epileptic seizures (PNES). The current study investigated the peri-ictal time course of heart rate variability (HRV) measures, which reflect autonomic nervous system functioning. Methods: HRV measures were extracted from electrocardiography data collected during 1-7 days of video- electroencephalography monitoring of 17 patients with epilepsy and 20 patients with PNES. Heart rate (HR) and HRV measures (standard deviation of average beat-to-beat intervals (SDANN), root mean square of successive differences (RMSSD), high frequency (HF) power, low frequency (LF) power and very low frequency (VLF) power) were averaged over consecutive five-minute intervals. Quantitative analyses of Poincaré plot parameters (SD1, SD2 and SD1/SD2 ratio) were also performed. In addition, differences with HRV parameters of patients with PNES were explored. Results: In epilepsy, no significant pre-ictal changes in HR and HRV parameters were observed. During seizures, HR, SDANN, SD1 and SD1/SD2 ratio significantly increased while VLF power significantly decreased. In the five-minute interval immediately following seizures, HR, SDANN and SD1 were back to pre-seizure levels, while VLF power remained significantly decreased and SD1/SD2 ratio remained significantly increased. Significant between-group differences were identified for several pre-ictal and ictal HRV parameters, but not for post-ictal measurements. Conclusion: The ictal HR and HRV changes reflect increased sympathetic system activation during epileptic seizures. The HRV parameters of patients with epilepsy differed significantly from the peri-ictal HRV pattern of patients with PNES, which suggested increased sympathetic system activation and decreased vagal tone shortly before PNES and return to normal levels shortly after the episode. Implications for differential diagnosis and treatment are discussed. Keywords: Epilepsy; Psychogenic; Non-epileptic seizures; Heart rate variability; Vagal tone; Autonomic nervous system Introduction Epileptic seizures result from brief episodes of abnormal excessive and synchronous neuronal activity in the brain. Examination of heart rate variability (HRV) parameters, which reflect (co-)activation of the sympathetic and parasympathetic branches of the autonomic nervous system in epilepsy, has previously identified altered sympathetic and vagal tone during interictal and ictal states [1-7]. These findings may have important meaning for our insight in the prognosis of epilepsy. For example, the ictal reduction of the vagal tone that has been repeatedly observed has been suggested to be one of the reasons for sudden unexpected death in epilepsy (SUDEP) [8,9]. A more detailed analysis of how HRV parameters change in the immediate pre-ictal period may be useful for seizure prediction paradigms, which could be used in vagal nerve or deep brain stimulators or for the purpose of real time seizure detection in physiological monitoring devices [6]. Therefore, the current study examined the peri-ictal HRV pattern associated with epileptic seizures. In addition, we investigated peri-ictal HRV patterns of psychogenic non-epileptic seizures (PNES), which are epilepsy-like episodes that lack epileptiform brain activity on the electroencephalogram (EEG), but instead originate from psychogenic factors [10,11]. Differences between the peri-ictal patterns of HRV changes in epilepsy and PNES Neurology & Neurophysiology van der Kruijs et al., J Neurol Neurophysiol 2014, 5:4 http://dx.doi.org/10.4172/2155-9562-5-1000215 Research Article Open Access J Neurol Neurophysiol ISSN:2155-9562 JNN, an open access journal Volume 5 • Issue 4 • 1000215