Familial intracranial aneurysm, the relationship of the aortic diameter

Familial predisposition appears as an identified risk factor for cerebrovascular disease. The primary objective of our study was to assess intracranial aneurysm (IA) recurrence rate in a population of familial IA. Secondary objectives were first to analyse the inheritance categorisation/pattern of these families and second to assess the correlation between the aortic diameter on MRI and the aneurysmal characteristics.

Over a period of 20 years (1990-2010), 26 patients from 23 families, identified from a regional register, accepted to participate in this prospective trial in order to determine, the inheritance pattern, the screening of de novo aneurysms by CT angioscan, and the aortic mensuration by MRI. The transmission pattern was categorised into autosomal dominant inheritance, autosomal recessive and autosomal dominance with incomplete penetrance. The aortic diameter was measured: anatomic coverage in the caudo-cranial direction from the iliac arteries to the ventriculo-aortic junction.

All 26 patients [from 55.4 ± 11.2 years, sex ratio female/male: 1.36] were reviewed after a mean follow-up of 7.9 ± 6.6 years after the diagnosis of a cerebral aneurysm. The characteristics of this population were the diagnostic circumstances such as a subarachnoid hemorrhage (SAH) in 14 (53.8%), the multiple locations in 10 (38.5%) and a giant aneurysm in 4 (15.4%). Four de novo aneurysms were diagnosed in 3 patients (11.5%) after a mean follow-up of 22.3 ± 4 years, which corresponds to an annual incidence of 1.9 (95% CI 1.4-2.6%). The transmission pattern was autosomal dominant in 16 (61.5%), recessive in 3 (11.5%) and not defined in 7 (26.9%). As regards the aortic diameter, a significant decrease in the aortic diameter was observed in patients with an aneurysmal diameter superior to 10mm.

The rate of de novo aneurysm justifies prolonged monitoring by imaging of these patients with familial intracranial aneurysm. The narrowing of the terminal part of the aorta could be a hemodynamic factor involved into the IA development.