title: Evaluation of the autonomic cardiovascular response in Arnold-Chiari deformities and cough syncope syndrome.
abstract: OBJECTIVE
  To study the autonomic control of heart rate in patients with Arnold-Chiari deformity types I and II who exhibit the signs and symptoms of cough syncope syndrome.
  
  
  METHODS
  Prospective, clinical descriptive study.
  
  
  METHODS
  University clinical research center.
  
  
  METHODS
  Nine patients with Arnold-Chiari deformity and cough syncope syndrome.
  
  
  METHODS
  None.
  
  
  METHODS
  Changes in heart rate, blood pressure, and electrocardiograms for power spectral analysis of heart rate variability were studied in the supine and standing positions, preoperatively (n = 9) and postoperatively (n = 5).
  
  
  RESULTS
  Preoperatively, 8 (89%) of 9 patients increased their heart rate after postural change from supine to standing (mean +/- SD delta = 13 +/- 13 beats per minute [bpm]). Postoperatively, 4 (80%) of the 5 patients exhibited a greater increase in standing heart rate (mean delta = 19 +/- 16 bpm) compared with preoperative values. Changes in systolic, diastolic, and mean blood pressure with postural change were variable. Preoperatively, all patients exhibited abnormal control of heart rate in response to postural change. Three patients (33%) showed an abnormal decrease in low-frequency heart rate power (mean delta = -27 +/- 35 bpm2); the remaining 6 (67%) demonstrated an abnormal increase in high-frequency heart rate power (mean delta = 25 +/- 41 bpm2). All patients were clinically asymptomatic at 2 months after surgery. A normal spectral response to postural change was demonstrated in heart rate power in all 5 patients who were reevaluated postoperatively, with an increase in low-frequency power (mean delta = 33 +/- 21 bpm2) and a decrease in high-frequency power (mean delta = -21 +/- 23 bpm2).
  
  
  CONCLUSIONS
  Patients with cervicomedullary anatomic abnormalities caused by Arnold-Chiari deformities may exhibit abnormal autonomic control of heart rate, and the autonomic control of their heart rate returns to a normal pattern after surgical palliation in conjunction with resolution of clinical symptoms.
authors.affiliation: Division of Neurosurgery, University of Rochester School of Medicine and Dentistry, NY, USA.
authors.forename: P D
authors.initials: PD
authors.lastname: Ireland
authors.forename: D
authors.initials: D
authors.lastname: Mickelsen
authors.forename: T G
authors.initials: TG
authors.lastname: Rodenhouse
authors.forename: R S
authors.initials: RS
authors.lastname: Bakos
authors.forename: B
authors.initials: B
authors.lastname: Goldstein
mesh_terms: D000293:Adolescent; D000328:Adult; D001139:Arnold-Chiari Malformation / Q000503:physiopathology* / Q000601:surgery; D001341:Autonomic Nervous System / Q000503:physiopathology; D001342:Autonomic Nervous System Diseases / Q000503:physiopathology* / Q000601:surgery; D001794:Blood Pressure / Q000502:physiology*; D002648:Child; D003371:Cough / Q000503:physiopathology*; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000503:physiopathology; D012815:Signal Processing, Computer-Assisted; D013575:Syncope / Q000503:physiopathology*; D013577:Syndrome