title: The influence of hemodynamic stress factors on intracranial aneurysm formation.
abstract: OBJECTIVE
  Applanation tonometry is a noninvasive method of assessing both peripheral and central arterial blood pressure (BP) profiles. In this study the authors examine whether there are differences in these profiles in patients with intracranial aneurysms when compared with age-matched controls.
  
  
  METHODS
  Carotid artery (CA) and derived aortic BP waveforms were obtained using a pulse wave analysis system. The ratio of the pressure wave amplitude above the systolic shoulder to the total systolic BP (augmentation index [AI]) was recorded. One hundred seventy-three patients with intracranial aneurysms (23 unruptured lesions) and 173 healthy control volunteers were examined. For the patients with aneurysms the right and left CA AIs (mean +/- standard deviation) were 125.6 +/- 23.1% and 128.3 +/- 22.1%, respectively. Corresponding values for the control group were 118.4 +/- 22.6% and 119.4 +/- 21.8%. The calculated AI for the ascending aorta was 29.8 +/- 10.5% and 25.6 +/- 12.2% for patients with aneurysms and control volunteers, respectively. Significant asymmetry in CA AI was seen in patients with aneurysms, the left being greater (p = 0.002). No significant differences were seen in mean BP (108 +/- 14 mm Hg in patients with aneurysms compared with 106 +/- 16 mm Hg in controls; p = 0.2). Multivariate analysis excluded the influence of BP and other potential confounding vascular risk factors for increased AI.
  
  
  CONCLUSIONS
  Significant differences in AI, both in magnitude and symmetry, were identified in patients with intracranial aneurysms when compared with matched controls.
authors.affiliation: University Department of Neurosurgery, Addenbrooke's Hospital, Cambridge, United Kingdom.
authors.forename: C L
authors.initials: CL
authors.lastname: Turner
authors.forename: S
authors.initials: S
authors.lastname: Tebbs
authors.forename: P
authors.initials: P
authors.lastname: Smielewski
authors.forename: P J
authors.initials: PJ
authors.lastname: Kirkpatrick
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001011:Aorta / Q000503:physiopathology; D001794:Blood Pressure; D002339:Carotid Arteries / Q000503:physiopathology; D005260:Female; D006439:Hemodynamics; D006801:Humans; D002532:Intracranial Aneurysm / Q000209:etiology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011674:Pulse; D012016:Reference Values; D012307:Risk Factors; D013312:Stress, Physiological / Q000150:complications*; D013599:Systole; D014065:Tonometry, Ocular / Q000379:methods