Morphometric analysis of reticular and elastin fibers in the cerebral arteries of patients with intracranial aneurysms.

Elastin and reticular fibers were identified using standard histological strains in middle cerebral arteries taken from patients who had died from aneurysmal subarachnoid hemorrhage and control patients who did not have cerebral aneurysms. Examination of cerebral arteries from normal individuals revealed a dense network of fine reticular fibers in the arterial media that were uniformly distributed. Computerized morphometric analysis indicated that reticular fibers in the arterial media of cerebral arteries were significantly decreased in patients with aneurysms. In addition, these fibers were irregularly distributed and shortened when compared to those seen in control arteries. In both patients with aneurysms and control patients, elastin fibers were limited almost exclusively to the internal elastin lamina. No differences were observed in the appearance or content of elastin fibers in control patients and patients with aneurysm. Although other explanations cannot be excluded, these observations are consistent with the hypothesis that "intrinsic" abnormalities in the walls of cerebral arteries lead to conditions that favor the formation and rupture of cerebral aneurysms.