FAMILIAL SUBARACHNOID HEMORRHAGE - DISTINCTIVE FEATURES AND PATTERNS OF INHERITANCE

To delineate the distinctive features of familial subarachnoid hemorrh age, we compared gender and age at the time of subarachnoid hemorrhage , as well as site and number of aneurysms, in patients with familial s ubarachnoid hemorrhage (at least 1 first-degree relative with subarach noid hemorrhage)and patients with sporadic subarachnoid hemorrhage (no subarachnoid hemorrhage in first- or second-degree relatives),in a pr ospective, hospital-based series of patients. In addition we studied t he pattern of inheritance in 17 families with familial subarachnoid he morrhage. Mean age at the time of hemorrhage in patients with the fami lial form was 6.8 years lower than that in those with the Sporadic for m, and middle cerebral artery aneurysms occurred more often in patient s with familial disease. Sex distribution and number of aneurysms were similar in the two groups. Inheritance was compatible with autosomal dominant transmission in some families, and with autosomal recessive o r multifactorial transmission in others. In our 5 families as well as in all 18 previously reported families with two affected generations, the age at the time of subarachnoid hemorrhage was invariably lower in later generations, which is suggestive of anticipation. We conclude t hat familial subarachnoid hemorrhage is a separate entity with occurre nce at a young age, predilection for aneurysms of the middle cerebral artery, and variable modes of inheritance, including autosomal dominan t inheritance with possible anticipation.