Posterior reversible encephalopathy syndrome (PRES) is a neurological disorder of reversible subcortical vasogenic edema resulting from endothelial injury due to abrupt blood pressure changes or direct effects of cytokines.  PRES is characterized by encephalopathy, headaches, seizures, and visual disturbances.  PRES is often seen in the setting of renal failure, autoimmune disorders, or may be induced by medications or drugs.  Neuroimaging may reveal ischemic strokes, intraparenchymal hemorrhage, or sulcal subarachnoid hemorrhage.  Black cohosh is a dietary supplement of the buttercup family claimed to have estrogenic effects used primarily for relief of menopausal symptoms. 

We describe a case of a 36 year-old woman who developed PRES shortly after initiating black cohosh for the treatment of hot flashes. 

A 36 year-old woman with history of hypertension and uterine fibroids post hysterectomy presented with sudden onset headache. She had started taking black cohosh the day of presentation.  CT brain showed a right posterior parietal intraparenchymal hemorrhage with surrounding edema and adjacent sulcal subarachnoid hemorrhage. Cerebral angiogram revealed multifocal irregularity of the right parietal branches of the MCA. The patient was started on verapamil 120mg three times daily and treated with strict blood pressure control.  She was initially monitored in the neurointensive care unit and discharged home three days later.  The patient was instructed to stop using black cohosh and her headache resolved over the next three weeks.  Follow up cerebral angiography three months later revealed resolution of multifocal vasoconstriction of the right parietal branches.  

Early diagnosis, treatment, and discontinuation of the offending agent are important to minimize long term neurological sequelae in PRES.  Review of patient medications and herbal supplements may help determine unusual triggers for PRES.  Further studies are warranted to determine the association of black cohosh with PRES.