Familial intracranial aneurysm and infundibular widening.

We present details of a family who show a high incidence of both intracranial saccular aneurysm and infundibular widening. Familial aneurysms are compared with aneurysms occurring in the general populations with regard both to site distribution and age of onset of symptoms. The possibility of infundibular widening being preaneurysmal is further discussed. It is highly likely that the mode of inheritance in familial cases is one of dominance.