title: Decreased cerebral vasomotor reactivity in patients with obstructive sleep apnea syndrome.
abstract: In obstructive sleep apnea syndrome (OSAS), any of the activated neural, vascular, hemodynamic, metabolic, inflammatory, and thrombotic mechanisms may be related to increased cerebrovascular disease and risk of death; however, the possible pathophysiological process between obstructive sleep apnea syndrome and stroke has not been clearly explained. We hypothesize that alterations in vasomotor reactivity in patients may be responsible for their altered cerebral blood flow, and may contribute to the increased risk of ischemic stroke.
  
  
  
  A total of 30 untreated patients with severe obstructive sleep apnea and 26 control subjects were included in the study. The mean blood flow velocity and breath holding index were measured in middle cerebral artery bilaterally in both patient and control groups by using transcranial Doppler ultrasound. We compared the values between two groups.
  
  
  
  The mean blood flow velocity and breath holding indexes were significantly decreased in the patient group when compared with the control group. There were no correlations between cerebral hemodynamic parameters and polysomnographic findings in patients.
  
  
  
  Our findings suggest that there was a deteriorated vasodilator response to hypercapnia in patients with OSAS. This deterioration may stem from chemoreceptors or endothelial damages that lead to vascular relaxation and vasodilatation in cerebrovascular circulation. This impaired cerebral vascular regulation may contribute to the increased risk of stroke in patients with OSAS.
authors.affiliation: Department of Neurology, Gulhane Military Medical Academy, Ankara, Turkey. Electronic address: oz_oguzhan@yahoo.com.
authors.forename: Oguzhan
authors.initials: O
authors.lastname: Oz
authors.affiliation: Neurology Service, Beytepe Military Hospital, Ankara, Turkey.
authors.forename: Serdar
authors.initials: S
authors.lastname: Tasdemir
authors.affiliation: Department of Neurology, Gulhane Military Medical Academy, Ankara, Turkey.
authors.forename: Hakan
authors.initials: H
authors.lastname: Akgun
authors.affiliation: Department of Psychiatry, Gulhane Military Medical Academy, Ankara, Turkey.
authors.forename: Murat
authors.initials: M
authors.lastname: Erdem
authors.affiliation: Department of Psychiatry, Gulhane Military Medical Academy, Ankara, Turkey.
authors.forename: Adem
authors.initials: A
authors.lastname: Balikci
authors.affiliation: Department of Neurology, Gulhane Military Medical Academy, Ankara, Turkey.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Cetiz
authors.affiliation: Department of Neurology, Gulhane Military Medical Academy, Ankara, Turkey.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Yucel
authors.affiliation: Department of Neurology, Gulhane Military Medical Academy, Ankara, Turkey.
authors.forename: Umit Hidir
authors.initials: UH
authors.lastname: Ulas
authors.affiliation: Department of Neurology, Gulhane Military Medical Academy, Ankara, Turkey.
authors.forename: Seref
authors.initials: S
authors.lastname: Demirkaya
authors.affiliation: Department of Neurology, Gulhane Military Medical Academy, Ankara, Turkey.
authors.forename: Yasar
authors.initials: Y
authors.lastname: Kutukcu
authors.affiliation: Department of Psychiatry, Gulhane Military Medical Academy, Ankara, Turkey.
authors.forename: Fuat
authors.initials: F
authors.lastname: Özgen
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*; D017585:Ultrasonography, Doppler, Transcranial
keywords: Breath holding index; Mean blood flow velocity; Transcranial Doppler