Reversible Cerebral Vasculopathy Resembling Reversible Cerebral Vasoconstriction Syndrome in a Case of Untreated Basedow's (Graves') Disease.

Reversible cerebral vasoconstriction syndrome (RCVS) involves transient, multifocal cerebral artery narrowing. We report the case of a 42-year-old woman presenting with thunderclap headaches one month after thyrotoxicosis onset. Brain computed tomography and magnetic resonance imaging (MRI) were unremarkable, but magnetic resonance angiography (MRA) revealed focal narrowing of the M2 segment of the right middle cerebral artery. Initial treatment with intravenous nicardipine failed to relieve symptoms. After diagnosing Basedow's (Graves') disease and initiating antithyroid therapy, the headaches markedly improved. This case suggests that RCVS may be triggered by thyrotoxicosis alone and that RCVS secondary to Graves' disease may resolve with appropriate antithyroid treatment.