title: Autonomic dysfunction affects cerebral neurovascular coupling.
abstract: OBJECTIVE
  Autonomic failure (AF) affects the peripheral vascular system, but little is known about its influence on cerebrovascular regulation. Patients with familial amyloidotic polyneuropathy (FAP) were studied as a model for AF.
  
  
  METHODS
  Ten mild (FAPm), 10 severe (FAPs) autonomic dysfunction FAP patients, and 15 healthy controls were monitored in supine and sitting positions for arterial blood pressure (ABP) and heart rate (HR) with arterial volume clamping, and for blood flow velocity (BFV) in posterior (PCA) and contralateral middle cerebral arteries (MCA) with transcranial Doppler. Analysis included resting BFV, cerebrovascular resistance parameters (cerebrovascular resistance index, CVRi; resistance area product, RAP; and critical closing pressure, CrCP), and neurovascular coupling through visually evoked BFV responses in PCA (gain, rate time, attenuation, and natural frequency).
  
  
  RESULTS
  In non-stimulation conditions, in each position, there were no significant differences between the groups, regarding HR, BP, resting BFV, and vascular resistance parameters. Sitting ABP was higher than in supine in the three groups, although only significantly in controls. Mean BFV was lower in sitting in all the groups, lacking statistical significance only in FAPs PCA. CVRi and CrCP increased with sitting in all the groups, while RAP increased in controls but decreased in FAPm and FAPs. In visual stimulation conditions, FAPs comparing to controls had a significant decrease of natural frequency, in supine and sitting, and of rate time and gain in sitting position.
  
  
  CONCLUSIONS
  These results demonstrate that cerebrovascular regulation is affected in FAP subjects with AF, and that it worsens with orthostasis.
authors.affiliation: Department of Neurology, Hospital São João, Alameda Professor Hernani Monteiro, Porto, Portugal. elsaazevedo@netcabo.pt
authors.forename: Elsa
authors.initials: E
authors.lastname: Azevedo
authors.forename: Pedro
authors.initials: P
authors.lastname: Castro
authors.forename: Rosa
authors.initials: R
authors.lastname: Santos
authors.forename: João
authors.initials: J
authors.lastname: Freitas
authors.forename: Teresa
authors.initials: T
authors.lastname: Coelho
authors.forename: Bernhard
authors.initials: B
authors.lastname: Rosengarten
authors.forename: Ronney
authors.initials: R
authors.lastname: Panerai
mesh_terms: D000328:Adult; D017772:Amyloid Neuropathies / Q000150:complications; D001342:Autonomic Nervous System Diseases / Q000150:complications*; D002561:Cerebrovascular Disorders / Q000150:complications*; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged