Serial testing of the ICHD

To serially test the International Classification of Headache Disorders (ICHD) 3rd edition beta version criteria for 6.7.3.1 probable reversible cerebral vasoconstriction syndrome (probable RCVS) in patients with thunderclap headache. We prospectively screened consecutive patients with thunderclap headache who visited the Samsung Medical Center between October 2015 and March 2017. Patients were included in the analysis if they a) visited our hospital within 1 month after onset, b) completed a diagnostic work-up, and c) had no secondary causes other than RCVS. The ICHD-3 beta 6.7.3.1 criteria were evaluated serially during the first visit (visit 1), 2 weeks after the first visit (visit 2), and 1–3 months after onset (visit 3). A total of 99 patients completed this study. Based on the first clinical and radiological evaluation, 63 (63.6%) were diagnosed with angiogram-proven RCVS, whilst 36 (36.4%) showed normal neuroimaging. The ICHD-3 beta 6.7.3.1 criteria were fulfilled in 76.2% of patients with angiogram-proven RCVS. In patients with normal angiograms, the ICHD diagnosis of probable RCVS changed over time: 25.0%, 47.2%, and 38.9% at visits 1, 2, and 3, respectively. The sensitivity and specificity of the criteria at visit 1 were 72.4% and 95.5%, respectively, for the prediction of a final diagnosis of overall (angiogram-proven？+？probable) RCVS. The ICHD-3 beta criteria for probable RCVS are applicable for patients with thunderclap headaches at the acute stage, with the exception of criterion C3. Criteria C1 and C2 are less reliable when applied at the first visit. Repeated evaluation is necessary to enhance diagnostic sensitivity