title: Cannabis and stroke: systematic appraisal of case reports.
abstract: OBJECTIVE
  An increasing number of case reports link cannabis consumption to cerebrovascular events. Yet these case reports have not been scrutinized using criteria for causal inference.
  
  
  METHODS
  All case reports on cannabis and cerebrovascular events were retrieved. Four causality criteria were addressed: temporality, adequacy of stroke work-up, effects of rechallenge, and concomitant risk factors that could account for the cerebrovascular event.
  
  
  RESULTS
  There were 34 case reports on 64 patients. Most cases (81%) exhibited a temporal relationship between cannabis exposure and the index event. In 70%, the evaluation was sufficiently comprehensive to exclude other sources for stroke. About a quarter (22%) of patients had another stroke after subsequent re-exposure to cannabis. Finally, half of patients (50%) had concomitant stroke risk factors, most commonly tobacco (34%) and alcohol (11%) consumption.
  
  
  CONCLUSIONS
  Many case reports support a causal link between cannabis and cerebrovascular events. This accords well with epidemiological and mechanistic research on the cerebrovascular effects of cannabis.
authors.affiliation: From the Division of Clinical Pharmacology, Department of Medicine, Western University, London, Ontario, Canada. dhackam@uwo.ca.
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Hackam
mesh_terms: D000293:Adolescent; D000328:Adult; D000428:Alcohol Drinking; D002188:Cannabis / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008385:Marijuana Smoking / Q000009:adverse effects*; D008875:Middle Aged; D012307:Risk Factors; D012907:Smoking; D020521:Stroke / Q000139:chemically induced* / Q000209:etiology; D013997:Time Factors; D055815:Young Adult
keywords: case management; epidemiology; risk factors; stroke; substance-related disorders