Reader response: RCVS2 score and diagnostic approach for reversible cerebral vasoconstriction syndrome

We read with interest the article by Rocha et al.,¹ who developed a new diagnostic tool to distinguish reversible cerebral vasoconstriction syndrome (RCVS) from other intracranial arteriopathies. The RCVS2 score performed perfect specificity and sensitivity for the differential diagnosis between RCVS and non-RCVS arteriopathy at admission. However, there were some issues, which should be raised. First, as a retrospective study, there was a limited sample size in a stroke center (30 RCVS vs 80 non-RCVS). Prospective studies with larger samples from multiple centers in the other sites of the United States or the other countries are urgently needed to confirm. Second, besides the objective 3 variables of RCVS2 score (carotid artery involvement, sex, and subarachnoid hemorrhage), both the thunderclap headache and vasoconstrictive trigger were derived from the patients' subjective complaints and lack of golden standard to assess, which may lead to higher false positivity. Third, using the data from a published cohort,² this study only validated to distinguish RCVS from primary angiitis of the CNS, not including all the non-RCVS arteriopathies just as mentioned in the derivation cohort, such as moyamoya disease, intracranial atherosclerosis, secondary vasculitis, and radiation-induced arteriopathy. As a quite novel tool for accurate differential diagnosis of RCVS and non-RCVS, more available clinical variables, imaging features (such as vascular wall imaging³ and transcranial color-coded sonography⁴), and other biomarkers are warranted to confirm such findings.