A Case of Reversible Cerebral Vasoconstriction Syndrome in a Healthy Adult Male.

Reversible cerebral vasoconstriction syndrome (RCVS) represents a potentially under-recognized cause of thunderclap headache in patients presenting to the ED. While a rarely made diagnosis in emergency medicine practice, RCVS may be as common as subarachnoid hemorrhage (SAH). RCVS typically presents as a sudden onset, excruciating headache that may be associated with nausea, vomiting, photophobia, or other features with overlap in the clinical presentation of both SAH and migraine headaches. As a result of historical features overlapping the presentation of SAH, particularly the rapidity of onset and peak of severity, these patients are typically investigated for SAH and when that workup ultimately is reassuring, clinicians may often misattribute RCVS symptoms as migrainous. We present a case of a 35-year-old healthy male who presented with a severe, sudden onset headache, nausea, and photophobia to the ED on four occasions within a nine-day period. He was initially investigated appropriately for SAH; receiving an unenhanced head CT and lumbar puncture, which were both unremarkable. Following this initial workup, he was assessed on several other occasions, treated symptomatically as a migraine, and discharged home. On the fourth ED visit a CT angiogram (CTA) was completed that demonstrated the characteristic "string of beads" appearance of the middle cerebral artery (MCA) diagnostic of RCVS. This case describes the key features and investigations of a patient with RCVS and highlights the importance of early and accurate diagnosis of thunder clap headache in which SAH has been excluded.