Acute Reversible Cerebral Vasoconstriction Syndrome With Low-Dose Dihydroergotamine Possibly Potentiated by Valproic Acid and Erenumab: A Case Report

Dihydroergotamine (DHE), in the setting of polypharmacy, may increase the possibility of reversible cerebral vasoconstriction syndrome (RCVS). A 64-year-old woman with chronic migraine and medication-overuse headache (on amitriptyline, duloxetine, erenumab) was electively admitted for 5 days of intravenous (IV) ketamine (up to 55 mg/h) to treat intractable migraine pain. On the seventh day, upon receiving her forth dose of IV DHE (0.25 mg) and the first of IV valproic acid (VPA) (500 mg) adjunctively, she developed acute bilateral decreased visual acuity, bitemporal visual field deficit, and unsteady gait. Brain magnetic resonance imaging/magnetic resonance angiography (MRI/MRA) showed confluent bilateral T2 hyperintensities with punctate restricted diffusion in the occipital lobes associated with multi-segmental narrowing involving anterior, middle, posterior cerebral, and basilar arteries consistent with RCVS. Verapamil was initiated, whereas DHE, neuroleptics, and serotonergic agents were discontinued. Though she continued to have constant, non-thunderclap migrainous headache, her other neurologic symptoms resolved in 24 h. Concomitant use of VPA and erenumab with DHE may result in RCVS. VPA likely displaces the protein-bound DHE causing a transient surge of free DHE level in the serum. Erenumab may have impaired the protective vasodilatory mechanism, augmenting DHE’s vasoconstrictive effect. This case report highlights the importance and awareness of such a drug-drug interaction with DHE. J Neurol Res. 2020;10(1):20-24 doi: https://doi.org/10.14740/jnr558