Prevalence of cervical fibromuscular dysplasia among aneurysmal subarachnoid hemorrhage patients

Background and Objectives: Fibromuscular dysplasia (FMD) is a vascular disorder affecting medium-sized arteries, including the extracranial cervical arteries, and can lead to aneurysmal subarachnoid hemorrhage (aSAH). We aimed to determine the prevalence of cervical FMD in aSAH patients and assess whether cervical FMD in these patients is associated with more severe aneurysmal disease and internal carotid artery (ICA) elongation. Methods: We retrospectively reviewed computed tomography angiography (CTA) scans acquired on admission in a consecutive series of aSAH patients (2019-2024). The prevalence of FMD in the extracranial segments of the ICA and vertebral arteries (VA) was determined. In addition differences in aneurysm size, number of aneurysms, rebleeding rates and ICA elongation were assessed between patients with and without FMD using logistic regression, adjusting for potential confounders. Results: Cervical FMD was identified in 40 of 485 aSAH patients (prevalence 8.3%, 95% confidence interval CI 6.0%-11.1%). aSAH patients with FMD were older, more frequently women and more likely to have hypertension than those without FMD. We found no statistically significant differences in aneurysm size, number of aneurysms, rebleeding rates, or ICA elongation. Discussion: We report a high prevalence (8.3%) of cervical FMD among aSAH patients, but no clear differences in aneurysm severity and ICA elongation compared to those without. Given the high prevalence, we recommend routine screening for cervical FMD in aSAH patients on CTA (or another angiography modality). If FMD is suspected, full-body CTA (or other angiographic modality) should be considered for further vascular assessment.