title: Autonomic dysfunction in chronic persistent dizziness.
abstract: OBJECTIVE
  To investigate the autonomic dysfunction in patients with chronic persistent dizziness using standardized autonomic function tests.
  
  
  METHODS
  We prospectively recruited 18 patients with chronic persistent dizziness after excluding other causes with extensive investigations. A standardized battery of autonomic tests including the head up tilt (HUT) test, Valsalva maneuver (VM), and heart rate (HR) response to deep breathing was performed.
  
  
  RESULTS
  Approximately eighty percent of the patients showed at least one abnormality in autonomic tests. Two patterns of autonomic abnormality were identified: sympathetic failure, including abnormal decrease in blood pressure (BP) during HUT test or abnormal sympathetic indices related with the BP recovery during late phase II and phase IV during VM, and sympathetic hyperactivity, including abnormal increase in HR response during HUT test or an exaggerated phase IV response manifesting increased β-adrenergic tone during VM.
  
  
  CONCLUSIONS
  Autonomic dysfunction is frequently found in patients with chronic persistent dizziness after excluding other causes with extensive investigations. Sympathetic failure or hyperactivity may be postulated as one of the possible causes of chronic persistent dizziness. Clinicians should be aware of the possibility of autonomic dysfunction in patients with chronic dizziness, even if the dizziness is not orthostatic but persistent.
authors.affiliation: Department of Neurology, Keimyung University School of Medicine, Daegu, Republic of Korea; Brain Research Institute, Keimyung University School of Medicine, Daegu, Republic of Korea.
authors.forename: Hyung
authors.initials: H
authors.lastname: Lee
authors.affiliation: Department of Neurology, Keimyung University School of Medicine, Daegu, Republic of Korea; Brain Research Institute, Keimyung University School of Medicine, Daegu, Republic of Korea. Electronic address: kha0206@dsmc.or.kr.
authors.forename: Hyun-Ah
authors.initials: HA
authors.lastname: Kim
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001342:Autonomic Nervous System Diseases / Q000175:diagnosis / Q000209:etiology*; D001794:Blood Pressure / Q000502:physiology; D002908:Chronic Disease; D004244:Dizziness / Q000150:complications*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged
keywords: Autonomic nervous system; Chronic disease; Dizziness; Sympathetic nervous system diseases; Tilt-table test; Valsalva maneuver