[Reversible Cerebral Vasoconstriction Syndrome (RCVS) Induced by a Chinese Herbal Medicine; Tokishigyakukagoshuyushokyoto].

A 52-year-old woman taking a Chinese herbal medicine for 10 months was admitted to our hospital for recurrent severe headaches, nausea and vomiting. Brain magnetic resonance imaging revealed convexity subarachnoid hemorrhage in the left occipital and parietal lobes. Brain magnetic resonance angiography (MRA) showed multifocal segmental stenosis of cerebral arteries. Clinical symptoms resolved after treatments with nicardipine and verapamil. Follow-up MRA at 31 days after the onset showed complete disappearance of multifocal stenosis of cerebral arteries, confirming the diagnosis of reversible cerebral vasoconstriction syndrome (RCVS). It was suggested that licorice and evodia fruit, which were components of a Chinese herbal medicine named tokishigyakukagoshuyushokyoto were the precipitating factors of vasoconstriction. It is important for physicians to recognize that herbal supplements could be one of the causes of RCVS. (Received January 22, 2019; Accepted April 3, 2019; Published July 1, 2019).