Persistent Headache Attributed to Past Reversible Cerebral Vasoconstriction Syndrome Demonstrating Significant Improvement with Fremanezumab

A 45-year-old woman with a history of migraine experienced thunderclap headaches, after which cerebral vasospasm was confirmed by brain magnetic resonance angiography. Nimodipine treatment initially improved the headache, but moderate daily headaches persisted despite vasospasm resolution. Conventional headache medications including topiramate, propranolol and amitriptyline proved ineffective. Treatment with fremanezumab, a calcitonin gene-related peptide (CGRP)-targeted therapy, resulted in significant reduction of headache frequency and intensity after 3 months. This case suggests the potential effectiveness of CGRP inhibition for persistent headaches following reversible cerebral vasoconstriction syndrome.