Neurovascular Involvement in Fibromuscular Dysplasia: A Clue for Reappraisal of Old Classifications.

backgroundFibromuscular dysplasia (FMD) is a non-atheromatous, non-inflammatory arteriopathy involving the medium and small-sized arteries virtually in all vascular beds. The most frequently involved arteries are cerebroafferent and renal arteries. The current classification of the diseases is mostly imaging based and two subtypes are defined: a multifocal one and a focal one. The multifocal pattern corresponds to the typical "string of beads", which is the most frequently reported subtype.

aimsIn this review, we are presenting the several phenotypes of FMD neuroimaging, including the associated conditions, mainly dissection and aneurysms. MATERIALS AND

methodsWe reviewed the literature on neurovascular subtypes of FMD starting from the historical angiographic studies, validated versu pathologuy.

resultsPrevious description of the diseases relied on angiographic appearance and had a close relationship with the pathological classification. In particular, the angiographic classification of the neurovascular involvement contained much more details than the current classification, including multifocal, focal and atypical subtypes. DISCUSSION: Atypical subtype was missed in the transition from pathology to non-invasive vascular imaging, but some features of the old classifications deserve to be retrieved in order to do not miss some phenotypes of FMD.

conclusionsThe different imaging phenotypes might correspond to different clinical and prognostic phenotypes and their description supports the need of an updated classification, taking into accounts the past imaging subtypes and helping to address the underdiagnoses of FMD.