title: Cardiovascular autonomic and hemodynamic responses to vagus nerve stimulation in drug-resistant epilepsy.
abstract: OBJECTIVE
  Vagus nerve stimulation (VNS) is used as an adjunctive therapy for treating patients with drug-resistant epilepsy. The impact of VNS on cardiovascular autonomic function remains to be fully understood. We determined changes in cardiovascular sympathetic and parasympathetic, and hemodynamic function in association with VNS in patients with drug-resistant focal epilepsy.
  
  
  METHODS
  Longitudinal (n=15) evaluation of beat-to-beat blood pressure (BP) and heart rate variability (HRV), baroreflex sensibility, and hemodynamic function performed before VNS implantation, 6-months after implantation, and a mean of 12-months after implantation; and cross-sectional study (n=14) of BP and HR variability and baroreflex sensitivity during VNS on and VNS off.
  
  
  RESULTS
  In the longitudinal study, no differences were observed between the baseline, the 6-month visit, and the final visit in markers of parasympathetic cardiovagal tone or baroreflex sensitivity. Systolic and diastolic BP upon 5-min of head-up tilt increased significantly after VNS implantation (Systolic BP: -16.69±5.65mmHg at baseline, 2.86±16.54mmHg at 6-month, 12.25±12.95mmHg at final visit, p=0.01; diastolic BP: -14.84±24.72mmHg at baseline, 0.86±16.97mmHg at 6-month, and 17±12.76mmHg at final visit, p=0.001).
  
  
  CONCLUSIONS
  VNS does not seem to produce alterations in parasympathetic cardiovagal tone, regardless of the laterality of the stimulus. We observed a slight increase in sympathetic cardiovascular modulations. These changes had no significant hemodynamic implications. These findings contribute to the understanding of potential mechanisms of action of VNS.
authors.affiliation: Epilepsy Unit, Biocruces Research Institute, Barakado, Bizkaia, Spain. Electronic address: inigo.garamendiruiz@osakidetza.eus.
authors.forename: Iñigo
authors.initials: I
authors.lastname: Garamendi
authors.affiliation: Epilepsy Unit, Biocruces Research Institute, Barakado, Bizkaia, Spain.
authors.forename: Marian
authors.initials: M
authors.lastname: Acera
authors.affiliation: Epilepsy Unit, Biocruces Research Institute, Barakado, Bizkaia, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Agundez
authors.affiliation: Department of Neurosurgery, Cruces University Hospital, Spain.
authors.forename: Lara
authors.initials: L
authors.lastname: Galbarriatu
authors.affiliation: Epilepsy Unit, Biocruces Research Institute, Barakado, Bizkaia, Spain.
authors.forename: Ainhoa
authors.initials: A
authors.lastname: Marinas
authors.affiliation: Department of Neurosurgery, Cruces University Hospital, Spain.
authors.forename: Iñigo
authors.initials: I
authors.lastname: Pomposo
authors.affiliation: Epilepsy Unit, Biocruces Research Institute, Barakado, Bizkaia, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Valle
authors.affiliation: Dysautonomia Center, Department of Neurology, New York University Medical Center, New York, NY, USA.
authors.forename: Jose-Alberto
authors.initials: JA
authors.lastname: Palma
authors.affiliation: Autonomic and Movement Disorders Unit, Biocruces Research Institute, Barakado, Bizkaia, Spain; Department of Neurosciences, University of Basque Country, Leioa, Spain. Electronic address: juancarlos.gomezesteban@osakidetza.eus.
authors.forename: Juan C
authors.initials: JC
authors.lastname: Gomez-Esteban
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology*; D017704:Baroreflex / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D003430:Cross-Sectional Studies; D000069279:Drug Resistant Epilepsy / Q000503:physiopathology* / Q000628:therapy*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D018709:Statistics, Nonparametric; D055536:Vagus Nerve Stimulation / Q000379:methods*; D055815:Young Adult
keywords: Autonomic nervous system; Blood pressure; Heart rate variability; Vagus nerve stimulation