title: Stroke chameleons.
abstract: BACKGROUND
  Many conditions called "stroke mimics" may resemble acute stroke. The converse of the "stroke mimic" is a presentation suggestive of another condition, which actually represents stroke. These would be "stroke chameleons." The recognition of a chameleon as stroke has implications for therapy and quality of care.
  
  
  METHODS
  We performed a retrospective chart review, including all cases for 1 year in which patients had a stroke missed on hospital presentation. Initial erroneous diagnoses were compared for all patients correctly admitted with those diagnoses to determine positive predictive value (PPV) for each chameleon.
  
  
  RESULTS
  Ninety-four cases were identified as chameleons where brain imaging revealed acute stroke. The common chameleons were initially diagnosed as altered mental status (AMS) (29, 31%), syncope (15, 16%), hypertensive emergency (12, 13%), systemic infection (10, 11%), and suspected acute coronary syndrome (ACS) (9, 10%). The total number of patients who were diagnosed with these conditions over the same year were AMS (393), syncope (326), hypertensive emergency (144), systemic infection (753), and suspected ACS (817) (total N = 2528). For each chameleon diagnosis, the PPV of each presentation for acute stroke was AMS (7%), syncope (4%), hypertensive emergency (8%), systemic infection (1%), and suspected ACS (1%).
  
  
  CONCLUSIONS
  Stroke chameleons may result in patients not receiving appropriate care. The largest proportions of chameleons were AMS, syncope, hypertensive emergency, systemic infection, and suspected ACS. Patients diagnosed with hypertensive emergency or AMS had an 8% and 7% chance of having an acute stroke. Physicians should consider stroke in patients with these diagnoses with a lower threshold to obtain neuroimaging with subsequent appropriate management.
authors: Department of Neurology, North Shore Long Island Jewish Medical Center, New Hyde Park, New York.
authors: Callum M
authors: CM
authors: Dupre
authors: Department of Neurology, North Shore Long Island Jewish Medical Center, New Hyde Park, New York. Electronic address: rlibman@lij.edu.
authors: Richard
authors: R
authors: Libman
authors: Department of Biology, Frostburg State University, Frostburg, Maryland.
authors: Samuel I
authors: SI
authors: Dupre
authors: Department of Neurology, North Shore Long Island Jewish Medical Center, New Hyde Park, New York.
authors: Jeffrey M
authors: JM
authors: Katz
authors: Department of Neurology, North Shore Long Island Jewish Medical Center, New Hyde Park, New York.
authors: Igor
authors: I
authors: Rybinnik
authors: Department of Emergency Medicine, Hofstra North Shore-LIJ School of Medicine, New Hyde Park, New York.
authors: Thomas
authors: T
authors: Kwiatkowski
mesh_terms: D003937:Diagnosis, Differential; D003951:Diagnostic Errors; D003952:Diagnostic Imaging / Q000379:methods; D006760:Hospitalization; D006801:Humans; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D020521:Stroke / Q000175:diagnosis* / Q000503:physiopathology / Q000523:psychology / Q000628:therapy; D013997:Time Factors
keywords: Acute stroke; hypertensive emergency; hypertensive encephalopathy; psychosis; stroke mimic; syncope