title: Comparing maximum autonomic activity of psychogenic non-epileptic seizures and epileptic seizures using heart rate variability.
abstract: OBJECTIVE
  The semiology of psychogenic non-epileptic seizures (PNES) can resemble epileptic seizures, and differentiation between epileptic seizures with no EEG-correlate and PNES can be challenging even for trained experts. Therefore, there has been a search for a quantitative measure, other than EEG and semiology that could distinguish PNES from epileptic seizures. We used ECG to measure heart rate variability (HRV) in order to compare maximum autonomic activity of epileptic seizures and PNES. These comparisons could potentially serve as biomarkers for distinguishing these types of clinical episodes.
  
  
  METHODS
  Forty-nine epileptic seizures from 17 patients and 24 PNES from 7 patients with analyzable ECG were recorded during long-term video-EEG monitoring. Moving windows of 100 R-R intervals throughout each seizure were used to find maximum values of Cardiac Sympathetic Index (CSI) (sympathetic tonus) and minimum values of Cardiac Vagal Index (CVI), Root-Mean-Square-of-Successive-Differences (RMSSD) and HF-power (parasympathetic tonus). In addition, non-seizure recordings of each patient were used to compare HRV-parameters between the groups.
  
  
  RESULTS
  The maximum CSI for epilepsy seizures were higher than PNES (P=0.015). The minimum CVI, minimum RMSSD and HF-power did not show significant difference between epileptic seizures and PNES (P=0.762; P=0.152; P=0.818). There were no statistical difference of non-seizure HRV-parameters between the PNES and epilepsy patients.
  
  
  CONCLUSIONS
  We found the maximum sympathetic activity accompanying the epileptic seizures to be higher, than that during the PNES. However, the great variation of autonomic response within both groups makes it difficult to use these HRV-measures as a sole measurement in distinguishing epileptic seizures from PNES.
authors.affiliation: Department of Neurophysiology, Aarhus University Hospital, Noerrebrogade 44, 8000 Aarhus C, Denmark. Electronic address: jespjepp@rm.dk.
authors.forename: Jesper
authors.initials: J
authors.lastname: Jeppesen
authors.affiliation: Department of Neurophysiology, Aarhus University Hospital, Noerrebrogade 44, 8000 Aarhus C, Denmark; Department of Clinical Neurophysiology, Danish Epilepsy Centre, Visby Álle 5, 4293 Dianalund, Denmark. Electronic address: Sandor.Beniczky@aarhus.rm.dk.
authors.forename: Sándor
authors.initials: S
authors.lastname: Beniczky
authors.affiliation: Department of Engineering, Aarhus University, Finlandsgade 22, 8200 Aarhus N, Denmark. Electronic address: pj@eng.au.dk.
authors.forename: Peter
authors.initials: P
authors.lastname: Johansen
authors.affiliation: Department of Neurology, Aarhus University Hospital, Noerrebrogade 44, 8000 Aarhus C, Denmark. Electronic address: Per.Sidenius@aarhus.rm.dk.
authors.forename: Per
authors.initials: P
authors.lastname: Sidenius
authors.affiliation: Department of Neurophysiology, Aarhus University Hospital, Noerrebrogade 44, 8000 Aarhus C, Denmark. Electronic address: Anders.Fuglsang@aarhus.rm.dk.
authors.forename: Anders
authors.initials: A
authors.lastname: Fuglsang-Frederiksen
mesh_terms: D001341:Autonomic Nervous System / Q000503:physiopathology*; D003937:Diagnosis, Differential; D004569:Electroencephalography / Q000379:methods; D004827:Epilepsy / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D012640:Seizures / Q000503:physiopathology*
keywords: Autonomic nerves system; Epileptic seizure; Heart rate variability (HRV); Psychogenic non-epileptic seizure (PNES); Sympathetic tonus