Reversible Cerebral Vasoconstriction Syndrome.

Background: Reversible cerebral vasoconstriction syndrome (RCVS) is an underappreciated and poorly understood cause of thunderclap headache (TCH). Although self-limited in the majority of patients, incidence is increasing, with presentations overlapping considerably with life-threatening conditions, such as aneurysmal subarachnoid hemorrhage and stroke. In addition, radiographic findings seen in RCVS are also present in primary angiitis of the central nervous system (PACNS). Misdiagnosis of RCVS might subject patients to unnecessary invasive testing and immunosuppressive therapy. Furthermore, the recommended treatment of glucocorticoids used in PACNS can be harmful in RCVS. RCVS is not a benign condition, as patients can have ischemic or hemorrhagic complications leading to persistent neurologic deficits and even death. Current treatments, guided only by expert consensus, have no proven effect on these complications, which argues the need for accurate identification of patients with RCVS and prospective studies to validate treatment and inform prognoses.

Case Report: We describe a previously healthy male who presented to the emergency department after 2 episodes of TCH and angiography consistent with RCVS. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: RCVS is a common but underappreciated cause of TCH. The likelihood of misdiagnosing RCVS following the accepted diagnostic algorithm of acute headache in the emergency department is high due to a lack of clinical awareness and common features shared with other headache syndromes. Emergency department physicians must broaden the differential in patients presenting to the emergency department with TCH to include RCVS and be familiar with the accepted treatments and appropriate follow-up.