Lack of evidence for an association between neurofibromatosis type I and intracranial aneurysms - Autopsy study and review of the literature

Background and Purpose-Neurofibromatosis type I (NFI) is an autosomal domin ant, hereditary, neurocutaneous syndrome purported to be associated with in tracranial aneurysms. To study the relationship between NFI and intracrania l aneurysms, we have analyzed all intracranial autopsies of NFI patients pe rformed at our institution from 1889 to 1999 and analyzed all intracranial aneurysm cases at our institution from 1990 to 1999 in an attempt to identi fy patients with NFI. In addition, we have reviewed published clinical seri es of NF1 patients. Methods-The autopsy database at our institution, which contains 50 000 case s from 1889 to 1999, was searched to identify NF1 patients, and the results of these autopsies were reviewed. The prevalence of intracranial aneurysms in these NFI patients was compared with the prevalence of intracranial ane urysms in our hospital's autopsy population and with the published prevalen ce of intracranial aneurysms in the general population. To identify patient s with intracranial aneurysms and NFI, our institution's intracranial aneur ysm database was searched for patients with clinical manifestations of NFl. Published clinical series of NF1 patients were identified through searches of the literature. Results-None of the 25 autopsy patients with NF1 had an intracranial aneury sm. None of the 925 patients treated for intracranial aneurysms were affect ed by NFl. A review of the literature identified 8 comprehensive clinical s tudies, all of which failed to document any relationship between NFI and in tracranial aneurysms. Conclusions-The autopsy prevalence of no NFI patients with intracranial ane urysms out of 25 is not different from the prevalence of intracranial aneur ysms in the general autopsy population. In addition, no patients treated fo r intracranial aneurysms at this institution had NFI. These findings are su pported by the observation that an association between NFI and intracranial aneurysms has never been identified in 8 large clinical studies of NFI pat ients. We conclude that there is a lack of evidence for any association bet ween NF1 and intracranial aneurysms.