A Retrospective Cohort Study of Cerebrovascular Fibromuscular Dysplasia

Background: Fibromuscular dysplasia (FMD) is a rare vasculopathy for which limited data are available particularly from Europe. Our aim was to study the clinical characteristics of a regional cohort of carotid fibromuscular dysplasia patients to assess their clinical outcomes and the rate of vascular complications.Methods: A retrospective cohort study of all cases of carotid/cerebrovascular FMD presenting to our regional vascular service (catchment population approximately 2 million), between 1998 and 2020. Imaging reports and patient case notes were screened using the keywords "FMD", "Fibromuscular Dysplasia", and "carotid". From case-note and imaging review, all relevant clin-ical data were extracted and the anatomical extent of vascular disease recorded.Results: Eighty six patients with a diagnosis of cerebrovascular fibromuscular dysplasia were identified on imaging (31 computed tomography angiography, 46 magnetic resonance angiog-raphy, and 9 digital subtraction angiography) by a neurovascular radiologist. The mean age was 64 years, 78 (90%) patients were female, and 45/59 (75%) were Caucasian. Presenting clinical syndromes were Stroke/transient ischemic attack in 54 (63%) patients, symptomatic intracranial aneurysm in 6 (10%), and other neurological symptoms (headache/migraine, tinnitus) in 14 (16%), with 11 (13%) presenting incidentally. Six patients (7%) had a positive fam-ily history of FMD (2 patients) or other cerebrovascular event (4 patients: carotid dissection, intracerebral bleed, or stroke). Eight patients (9%) had a known or suspected hereditary connec-tive tissue disorder (2 Ehlers-Danlos syndrome). Involved vessels were as follows: Carotid (mainly extracranial) in 79 (92%), vertebral 19 (22%), and a combination of these in 15 (17%) patients. Fifty eight (67%) patients had bilateral disease. Cerebrovascular complications were observed in 35 (41%) patients as follows: carotid dissection 11 (23%), carotid stenosis or occlu-sion 8 (9%), carotid aneurysm 8 (9%), cerebral aneurysm 9 (11%), vertebral aneurysm/dissec-tion 2 (2%), and carotid-cavernous fistula 2 (2%). Of the 22 patients who had extracranial imaging, 14 (60%) had FMD affecting other beds-renal artery in 8 (36%) patients, other visceral arteries in 4 (18%), and aorta in 2 (9%). In addition, 4 (18%) patients had aneurysm or dissection affecting renal, splenic, and lower limb arteries. Overall, 67 (80%) patients had FMD affecting more than 1 vessel and 50 (58%) had multisite FMD (>/ 1/4 2 vascular beds involved). Fifty nine (68%) patients were managed conservatively on close surveillance. Nineteen (21%) patients required carotid/cerebrovascular intervention and 9 (10%) required vascular interven-tion at other sites. Recurrent cerebrovascular events (stroke/transient ischemic attack, symp-tomatic Berry aneurysm) were seen in 20 (23%) patients. Overall mortality was 7% over a median follow-up period of 47 months.Conclusions: Carotid FMD patients have a high rate of multisite involvement, extracerebral vascular complications, and evidence of hereditary vasculopathy, requiring careful screening and surveillance.