Familial intracranial aneurysms: report of five families.

Five families are reported in which 13 members suffered aneurysmal subarachnoid haemorrhage. The presentation of five of these patients in a 12-month period suggests that familial aneurysms may be more common than previously reported. The clinico-pathological features of these patients are reviewed with reference to previously reported families. The putative roles of dietary factors, Type III collagen deficiency, smoking, oral contraceptive ingestion and hypertension in the aetiology of familial aneurysms are discussed.