Intracranial aneurysms are customarily divided into three chief etiologic types: congenital; arteriosclerotic and embolic. Of these three types, the congenital has proved the most interesting and in all probability the most numerous. The presence of defects in the media in this type of aneurysm was first shown by Forbus.1 Richardson and Hyland2 subsequently corroborated this observation.
Congenital anomalies are notoriously prone to occur in combinations, so that it is not surprising that congenital aneurysms have been reported in association with other developmental defects. The most frequently reported combination is that of aneurysm of the circle of Willis and coarctation of the aorta.3 Congenital polycystic kidney also is associated with other anomalies, the most frequent developmental defects being aberrant biliary cysts of the liver and pancreatic cysts. Aneurysm of the cerebral arteries is sometimes found with congenital polycystic kidney, a combination which has been recorded previously.
FORSTER FM, ALPERS BJ. ANEURYSM OF CIRCLE OF WILLIS ASSOCIATED WITH CONGENITAL POLYCYSTIC DISEASE OF THE KIDNEYS. Arch NeurPsych. 1943;50(6):669-676. doi:10.1001/archneurpsyc.1943.02290240053004