Morphological Analysis of Cerebral Artery Fenestrations and Their Correlation with Intracranial Aneurysms.

Abstract Background Fenestrations of cerebral arteries are congenital variants that develop when primitive vessels fuse incompletely. A association between the incidence of aneurysm on a fenestrated artery has been noted in the radiological literature. However, technical limitations of radiological studies may hamper visualization of small fenestrations and aneurysms. We sought to analyze a large, post-mortem collection of human brains to assess the association between aneurysm formation and the presence of fenestrations. Methods A 333 formalin-fixed brains were studied. The arachnoid was dissected under a microscope, the cerebral arteries were completely exposed, and fenestrations and aneurysms were identified and measured. For each specimen, the age, sex, and all vascular abnormalities and variations were recorded for analysis. Results Fenestrations were present in 41% of the cases, and 37% of these were multiple. Fenestrations were 3.1 ± 2.5 mm long and most commonly occurred in the anterior communicating artery (63%). Aneurysms were present in 8% of the specimens, usually in the anterior communicating artery or the middle cerebral artery. The detection of an aneurysm correlated with a fenestration was in 2% of all specimens (a total of four cases) and was not statistically significant (p = 0.18). Conclusions Fenestrations of the intracranial arteries are a common anatomical finding. They are present most often in the anterior communicating artery. Most of the aneurysms were detected in the anterior communicating artery and middle cerebral artery. We conclude that the co-existence of the aneurysm on the fenestrated artery is an incidental, rather than causal, relationship.