Permanent visual impairment following a Behçet's disease flare while on calcitonin gene-related peptide receptor antagonist therapy: a case report.

Background: Behçet's disease (BD) is a chronic, relapsing, systemic vasculitis that can involve both arteries and veins. Ocular involvement, including non-granulomatous panuveitis and occlusive retinal vasculitis, is common and a significant cause of morbidity. Erenumab is a monoclonal antibody targeting the calcitonin gene-related peptide (CGRP) receptor approved for migraine prevention Although it is generally well tolerated, recent concerns have emerged regarding its vasoconstrictive potential in patients with underlying vascular disorders.

Case presentation: We report a case of a 44-year-old woman with a history of BD, well-managed with azathioprine and methotrexate, who developed painless, bilateral subacute visual loss eleven days after receiving her second monthly dose of erenumab. This occurred during a BD flare marked by oral ulcers and severe migraine. Despite corticosteroid treatment, visual acuity did not improve. Erenumab was discontinued, but at her following visit four weeks later, vision remained impaired and visual fields showed blind spot enlargement and nonspecific defects.

Conclusion: We hypothesize that the patient's visual loss was due to secondary ischemia from BD-associated small-vessel vasculitis, potentially exacerbated by CGRP receptor blockade from erenumab, which may have impaired compensatory vasodilation in the optic nerve or retinal circulation. This case represents the first report of permanent bilateral visual impairment associated with CGRP antagonist use in a patient with BD. Recent FDA labeling updates for CGRP-targeting agents now caution against use in patients with preexisting vascular disease, including risk of hypertension and Raynaud's phenomenon. This case underscores the need for heightened caution when prescribing CGRP inhibitors to patients with systemic vasculitic disorders and highlights the importance of further investigation to better define the safety profile of these agents in individuals with underlying vascular disease.