title: Acute stroke chameleons in a university hospital: Risk factors, circumstances, and outcomes.
abstract: OBJECTIVE
  To identify risk factors, circumstances, and outcomes for individuals with acute ischemic stroke (AIS) chameleons (AIS-C) arriving in the emergency department of a university hospital.
  
  
  METHODS
  We retrospectively reviewed all patients with AIS from the prospectively constructed Acute Stroke Registry and Analysis of Lausanne during 8.25 years. AIS-C were defined as a failure to suspect stroke or as incorrect exclusion of stroke diagnosis. They were compared with patients diagnosed correctly at the time of admission.
  
  
  RESULTS
  Forty-seven of 2,200 AIS were missed (2.1%). These AIS-C were either very mild or very severe strokes. Multivariate analysis showed a younger age in patients with AIS-C (odds ratio [OR] per year 0.98, p < 0.01), less prestroke statin treatment (OR 0.29, p = 0.04), and lower diastolic admission blood pressure (OR 0.98 p = 0.04). They showed less eye deviation (OR 0.21, p = 0.04) and more cerebellar strokes (OR 3.78, p < 0.01). AIS-C were misdiagnosed as other neurologic (42.6% of cases) or nonneurologic (17.0%) disease, as unexplained decreased level of consciousness (21.3%), and as concomitantly present disease (19.1%). At 12 months, patients with AIS-C had less favorable outcomes (adjusted OR 0.21, p < 0.01) and higher mortality (adjusted OR 4.37, p < 0.01).
  
  
  CONCLUSIONS
  AIS are missed in patients with younger age with a lower cerebrovascular risk profile and may be masked by other acute conditions. Patients with chameleons present more often with milder strokes or coma, fewer focal signs and cerebellar strokes, and have higher disability and mortality rates at 12 months. These findings may be used to raise awareness in emergency departments to recognize and treat such patients appropriately.
authors.affiliation: From the Neurology Department (B.R., P.M.), Emergency Department (O.H., F.D., P.-N.C.), and Institute of Social and Preventive Medicine (M.F.), Centre Hospitalier Universitaire Vaudois and University of Lausanne, Switzerland. brichoz@gmail.com.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Richoz
authors.affiliation: From the Neurology Department (B.R., P.M.), Emergency Department (O.H., F.D., P.-N.C.), and Institute of Social and Preventive Medicine (M.F.), Centre Hospitalier Universitaire Vaudois and University of Lausanne, Switzerland.
authors.forename: Olivier
authors.initials: O
authors.lastname: Hugli
authors.affiliation: From the Neurology Department (B.R., P.M.), Emergency Department (O.H., F.D., P.-N.C.), and Institute of Social and Preventive Medicine (M.F.), Centre Hospitalier Universitaire Vaudois and University of Lausanne, Switzerland.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Dami
authors.affiliation: From the Neurology Department (B.R., P.M.), Emergency Department (O.H., F.D., P.-N.C.), and Institute of Social and Preventive Medicine (M.F.), Centre Hospitalier Universitaire Vaudois and University of Lausanne, Switzerland.
authors.forename: Pierre-Nicolas
authors.initials: PN
authors.lastname: Carron
authors.affiliation: From the Neurology Department (B.R., P.M.), Emergency Department (O.H., F.D., P.-N.C.), and Institute of Social and Preventive Medicine (M.F.), Centre Hospitalier Universitaire Vaudois and University of Lausanne, Switzerland.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Faouzi
authors.affiliation: From the Neurology Department (B.R., P.M.), Emergency Department (O.H., F.D., P.-N.C.), and Institute of Social and Preventive Medicine (M.F.), Centre Hospitalier Universitaire Vaudois and University of Lausanne, Switzerland.
authors.forename: Patrik
authors.initials: P
authors.lastname: Michel
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D004185:Disability Evaluation; D004636:Emergency Service, Hospital; D005260:Female; D006785:Hospitals, University / Q000706:statistics & numerical data*; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D020521:Stroke / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome