How Often Is Thunderclap Headache Caused by the Reversible Cerebral Vasoconstriction Syndrome?

BackgroundThunderclap headache (TCH) has a broad differential diagnosis that includes the reversible cerebral vasoconstriction syndrome (RCVS). It is believed to be caused by a dysregulation of vascular tone, which leads to reversible and segmental vasoconstriction and may cause permanent neurological deficits. One of the remaining mysteries is the incidence of the syndrome in a general hospital setting. MethodsWe recruited consecutive patients with TCH without evidence of aneurysmal subarachnoid hemorrhage on immediate computed tomography-scanning from the emergency room in a period of 12 months. Only those patients with an acute and severe onset of the pain were recruited; the peak of the pain had to be reached in less than 1 minute (verbal analog scale >8/10), and the minimum duration of the pain had to be 6 hours. All patients underwent lumbar puncture, magnetic resonance angiography, and serial transcranial Doppler sonography. ResultsThirty-four patients fulfilled the inclusion criteria; 3 of those were diagnosed with the RCVS (8.8%; 95% confidence interval 3-23). ConclusionsWe found the incidence of RCVS to be 8.8% (95% confidence interval 3-23) (3 patients) in patients presenting with TCH without evidence for severe illness. We believe that RCVS is an underrecognized condition, and therefore additional imaging should be performed in every patient with TCH.