Illicit Drugs and Reversible Cerebral Vasoconstriction Syndrome.

Reversible cerebral vasoconstriction syndrome (RCVS) is a condition characterized by thunderclap headache and associated vasospasm of the cerebral vasculature. A multitude of factors are considered to potentially predispose to the development of RCVS. These potential precipitants include numerous illicit drugs. In this study, we investigated the role of illicit drugs as a precipitating factor for RCVS, through systematic review of the relevant literature. We found the strongest evidence for cannabis, but a relative lack of evidence to support other illicit drugs, particularly as individual precipitating factors. We also identified a lack of the consistent application of diagnostic criteria for RCVS, which undoubtedly hampers advancement of knowledge in this field. Consistent adherence to diagnostic criteria will be important for future studies. Ultimately, a prospective registry of RCVS cases would be advantageous to advance understanding of the condition and its underlying causes.