Neurovascular brain dysplasias in neurofibromatosis Type 1 (NF1) patients: a magnetic resonance angiographic (MRA) study

Introduction: Among the rare cerebrovascular abnormalities found in patients with NF1, the most common is stenosis or occlusion of the cerebral arteries, which may have an appearance like the Moyamoya disease. Cerebral aneurysms and arteriovenous fistulae are described as well, although less commonly. Materials and methods: 80 patients with NF1 were studied with MR Imaging (MRI) of the brain and MRAof the intracranial arteries. Only 2 patients were submitted to an intracranial MRAwith a 0.5 Tesla, while 61 were studied with a 1.5 Tesla machine. The remaining 17 brain MRI were accurately reviewed, searching vessel asymmetries. 2 patients were also submitted respectively to CTA and MRA of extracranial arteries, with intravenous contrast injection because a sub-occlusive narrowing of the intracranial internal carotid artery had been previously found. Finally a patient, examined by MRI presented multiple intracranial arterial aneurisms. Results: Our patients did not show at MRI any ischemic lesion, being asymptomatic for such kind of pathology. Multiple intracranial arterial stenoses were found in 5 patients, respectively located: 1 at the carotid siphon, 2 at the supraclinoid carotid tracts, 2 involved the complete intracranial tract of the ICA, 4 the MCA, 3 the ACA, 2 the PCA, including a typical case of Moyamoya, showing a total of 5.64% of stenoses. We noted that ICA’s stenoses were already well appreciable on brain MRI, while other localizations were only detectable with MRA. The patient with a huge fusiform intracavernous aneurysm at left internal carotid artery with a second controlateral smaller aneurysm became symptomatic at the age of 21 when suddenly a left painful ophthalmoplegia manifested caused by an aneurysm trombosis better depicted by a subsequent MRA. Conclusions: Vascular stenoses in NF1 population is reported in about 2.5% of cases, probably underestimating the real incidence, because MR angiography (MRA) is not routinely executed. Our studies suggest that the percentage of brain vascular stenoses in NF1 patients is more elevated than those in literature reported, and also we believe that intracranial aneurysms in patients with NF1 deserve special attention. For this reason we recommend the routinely use of MR Angiography for NF1 patients during MR Imaging of brain