Arterial distensibility in patients with ruptured and unruptured intracranial aneurysms: Is it a predisposing factor for rupture risk?

Background: A risk factor assessment that reliably predicts whether patients are predisposed to intracranial aneurysm (IA) rupture has yet to be formulated. As such, the clinical management of unruptured IA remains unclear. Our aim was to determine whether impaired arterial distensibility and hypertrophic remodeling might be indicators of risk for IA rupture.
Material and Methods: The study population (n=49) was selected from consecutive admissions for either unruptured IA (n=23) or ruptured IA (n=26) from January to December 2010. Hemodynamic measures were taken from every patient, including systolic and diastolic blood pressure using a sphygmomanometer. Unruptured IA and ruptured IA characteristics, including aneurysmal shape, size, angle, aspect ratio, and bottleneck factor, were measured and calculated from transverse brain CT angiography images. With ultrasound, the right common carotid artery intima-media thickness was measured, as well as the lumen diameter during systole and diastole. Arterial wall strain, distensibility, stiffness index, and elastic modulus were calculated and compared between patients with unruptured IAs and ruptured IAs. A p-value less than 0.05 was considered statistically significant.
Results: General demographic data did not differ between patients with unruptured IAs and ruptured IAs. Greater mean intima-media thickness (p=0.013), mean stiffness index (p=0.044), and mean elastic modulus (p=0.026) were observed for patients with ruptured IAs. Moreover, mean strain (p=0.013) and mean distensibility (p=0.024) were decreased in patients with ruptured IAs.
Conclusions: Patients with ruptured IAs demonstrated decreased arterial distensibility and increased intima-media thickness at the level of the carotid arteries. By measuring these parameters via ultrasound, it may be possible to predict whether patients with existing IAs might rupture and hemorrhage into the subarachnoid space.

Keywords: Cerebral Angiography, carotid intima-media thickness, Cerebral Arteries - ultrasonography, elastic modulus, Hemodynamics, Intracranial Aneurysm - pathology, Risk Factors, Statistics, Nonparametric, Turkey - epidemiology, Vascular Stiffness