title: Autonomic nervous system functioning associated with psychogenic nonepileptic seizures: Analysis of heart rate variability.
abstract: OBJECTIVE
  Psychogenic nonepileptic seizures (PNESs) resemble epileptic seizures but originate from psychogenic rather than organic causes. Patients with PNESs are often unable or unwilling to reflect on underlying emotions. To gain more insight into the internal states of patients during PNES episodes, this study explored the time course of heart rate variability (HRV) measures, which provide information about autonomic nervous system functioning and arousal.
  
  
  METHODS
  Heart rate variability measures were extracted from double-lead electrocardiography data collected during 1-7days of video-electroencephalography monitoring of 20 patients with PNESs, in whom a total number of 118 PNESs was recorded. Heart rate (HR) and HRV measures in time and frequency domains (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. Additionally, quantitative analyses of Poincaré plot parameters (SD1, SD2, and SD1/SD2 ratio) were performed.
  
  
  RESULTS
  In the five-minute interval before PNES, HR significantly (p<0.05) increased (d=2.5), whereas SDANN (d=-0.03) and VLF power (d=-0.05) significantly decreased. During PNES, significant increases in HF power (d=0.0006), SD1 (d=0.031), and SD2 (d=0.016) were observed. In the five-minute interval immediately following PNES, SDANN (d=0.046) and VLF power (d=0.073) significantly increased, and HR (d=-5.1) and SD1/SD2 ratio (d=-0.14) decreased, compared to the interval preceding PNES.
  
  
  CONCLUSIONS
  The results suggest that PNES episodes are preceded by increased sympathetic functioning, which is followed by an increase in parasympathetic functioning during and after PNES. Future research needs to identify the exact nature of the increased arousal that precedes PNES.
authors.affiliation: Kempenhaeghe, P.O. Box 61, 5590AB Heeze, The Netherlands; School for Mental Health and Neuroscience, Maastricht University, P.O. Box 616, 6200MD Maastricht, The Netherlands. Electronic address: kruijss@kempenhaeghe.nl.
authors.forename: Sylvie J M
authors.initials: SJ
authors.lastname: van der Kruijs
authors.affiliation: Reference Centre for Refractory Epilepsy, Department of Neurology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium.
authors.forename: Kristl E J
authors.initials: KE
authors.lastname: Vonck
authors.affiliation: University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands.
authors.forename: Geert R
authors.initials: GR
authors.lastname: Langereis
authors.affiliation: University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands.
authors.forename: Loe M G
authors.initials: LM
authors.lastname: Feijs
authors.affiliation: Kempenhaeghe, P.O. Box 61, 5590AB Heeze, The Netherlands; School for Mental Health and Neuroscience, Maastricht University, P.O. Box 616, 6200MD Maastricht, The Netherlands.
authors.forename: Nynke M G
authors.initials: NM
authors.lastname: Bodde
authors.affiliation: Kempenhaeghe, P.O. Box 61, 5590AB Heeze, The Netherlands; Department of Neurology, Maastricht University Medical Centre, P.O. Box 5800, 6202AZ Maastricht, The Netherlands.
authors.forename: Richard H C
authors.initials: RH
authors.lastname: Lazeron
authors.affiliation: Reference Centre for Refractory Epilepsy, Department of Neurology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium.
authors.forename: Evelien
authors.initials: E
authors.lastname: Carrette
authors.affiliation: Kempenhaeghe, P.O. Box 61, 5590AB Heeze, The Netherlands; Reference Centre for Refractory Epilepsy, Department of Neurology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium.
authors.forename: Paul A J M
authors.initials: PA
authors.lastname: Boon
authors.affiliation: School for Mental Health and Neuroscience, Maastricht University, P.O. Box 616, 6200MD Maastricht, The Netherlands; Department of Radiology, Maastricht University Medical Centre, P.O. Box 5800, 6202AZ Maastricht, The Netherlands.
authors.forename: Walter H
authors.initials: WH
authors.lastname: Backes
authors.affiliation: School for Mental Health and Neuroscience, Maastricht University, P.O. Box 616, 6200MD Maastricht, The Netherlands; Department of Radiology, Maastricht University Medical Centre, P.O. Box 5800, 6202AZ Maastricht, The Netherlands.
authors.forename: Jacobus F A
authors.initials: JF
authors.lastname: Jansen
authors.affiliation: Kempenhaeghe, P.O. Box 61, 5590AB Heeze, The Netherlands; School for Mental Health and Neuroscience, Maastricht University, P.O. Box 616, 6200MD Maastricht, The Netherlands; Reference Centre for Refractory Epilepsy, Department of Neurology, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium; University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands; Department of Neurology, Maastricht University Medical Centre, P.O. Box 5800, 6202AZ Maastricht, The Netherlands.
authors.forename: Albert P
authors.initials: AP
authors.lastname: Aldenkamp
authors.affiliation: Kempenhaeghe, P.O. Box 61, 5590AB Heeze, The Netherlands; University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands.
authors.forename: Pierre J M
authors.initials: PJ
authors.lastname: Cluitmans
mesh_terms: D000328:Adult; D001143:Arousal / Q000502:physiology; D001341:Autonomic Nervous System / Q000503:physiopathology*; D004562:Electrocardiography; D004644:Emotions / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011602:Psychophysiologic Disorders / Q000503:physiopathology* / Q000523:psychology; D012640:Seizures / Q000503:physiopathology* / Q000523:psychology; D055815:Young Adult
keywords: Autonomic nervous system; Conversion disorder; Heart rate variability; Psychogenic nonepileptic seizures; Vagal tone