Marijuana, or cannabis, is one of the most commonly used illicit drugs worldwide. Although there are some case reports of stroke associated with cannabis use, there is no information on a causal role of cannabis in stroke. We identified 14 patients admitted to St Louis University Hospital between January 2004 and July 2007 with ischemic stroke who had documented clear exposure to cannabis during or before symptom onset and a positive urine screen for cannabis. We report this series, along with 3 cases previously reported by our group, for a total of 17 patients (13 men and 4 women), with a mean age of 41 years (range, 15-63 years). Nine patients were under age 45 years, 4 had a history of hypertension, and 10 sustained stroke in the posterior circulation. Headache, dysarthria, and ataxia were the most common presenting symptoms. Five patients had recurrent stroke with reexposure to cannabis. No patient had a prothrombotic state or cardiac source of embolism. Autopsy performed in 2 patients revealed hemorrhagic infarct with no evidence of vasculitis or embolus. The absence of other vascular risk factors in most of our patients, the temporal relation of symptom onset to cannabis exposure, and the recurrence of symptoms in a few patients with reexposure suggest a causal role of cannabis in these cases of ischemic stroke. However, this causal association cannot be definitely ascertained, given the descriptive nature of our series. More research is needed to explore this possible causal association.
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