OnabotulinumtoxinA injections: treatment of reversible cerebral vasoconstriction syndrome chronic daily headaches.

Reversible cerebral vasoconstriction syndrome (RCVS) is a rare condition characterised by repetitive, multifocal, vasofluctuations of cerebral arteries. A key symptom is chronic, disabling 'thunderclap' headaches, which are extremely difficult to treat as established medications may exacerbate the pathophysiology of RCVS. OnabotulinumtoxinA (OBT-A) injections are used for the prophylaxis of chronic daily headaches (CDH). The mechanism of action of OBT-A significantly differs from oral headache treatments. Thus, OBT-A may be an effective, safe treatment of RCVS-CDH. A 51-year-old woman with RCVS-CDH presented to outpatient clinic. This case report describes the first, believed, documented treatment of RCVS-CDH by OBT-A injections. In 2018, the consented patient received a total of 200 units of OBT-A, 155 units to the 31 approved U.S. Food and Drug Administration (FDA) sites and 45 units injected into the bilateral occipital belly of occipitofrontalis muscles. The patient reported 3 months of excellent pain relief (60% reduction). Three rounds of OBT-A injection, each 3 months apart, resulted in 80% reduction. OBT-A injections may prove a successful, novel treatment for RCVS-CDH.