Stroke Chameleons


      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.


      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.


      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%).


      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.

      Key Words

      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Journal of Stroke and Cerebrovascular Diseases
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Libman R.B.
        • Wirkowski E.
        • Alvir J.
        • et al.
        Conditions that mimic stroke in the emergency department. Implications for acute stroke trials.
        Arch Neurol. 1995; 52: 1119-1122
        • Kothari R.U.
        • Brott T.
        • Broderick J.P.
        • et al.
        Emergency physicians: accuracy in diagnosis of stroke.
        Stroke. 1995; 26: 2238-2241
        • Huff J.S.
        Stroke mimics and chameleons.
        Emerg Med Clin N Am. 2002; 20: 583-595
        • Carrera E.
        • Bogousslavsky J.
        The thalamus and behavior: effects of anatomically distinct strokes.
        Neurology. 2006; 66: 1817-1823
        • LaBresh K.
        • Reeves M.
        • Frankel M.
        • et al.
        Hospital treatment of patients with ischemic stroke or transient ischemic attack with Get With The Guidelines.
        Arch Intern Med. 2008; 168: 411-417
        • Benbaddis S.
        • Sila C.
        • Cristea R.
        Mental status changes and stroke.
        J Stroke Cerebrovasc Dis. 1994; 9: 216-219
        • Parvizi J.
        • Damasio A.R.
        Neuroanatomical correlates of brainstem coma.
        Brain. 2003; 126: 1523-1536
        • Schmahmann J.
        Vascular syndromes of the thalamus.
        Stroke. 2003; 36: 2264-2278
        • Davidson E.
        • Rotenberg Z.
        • Fuchs J.
        • et al.
        Transient ischemic attack-related syncope.
        Clin Cardiol. 2009; 14: 141-144
        • Qureshi A.
        Acute hypertensive response in patients with stroke: pathophysiology and management.
        Circulation. 2008; 118: 176-187
        • Zampaglione B.
        • Pascale C.
        • Marchisio M.
        • et al.
        Hypertensive urgencies and emergencies: prevalence and clinical presentation.
        Hypertension. 1996; 27: 144-147
        • Richards A.
        • Graham D.
        • Bullock R.
        Clinicopathophysiologic study of neurologic complications due to hypertensive disorders of pregnancy.
        J Neurol Neurosurg Psychiatry. 1988; 51: 416-421
        • Manolio T.
        • Olson J.
        • Longstreth W.
        Hypertension and cognitive function: pathophysiologic effects of hypertension on the brain.
        Curr Hypertens Rep. 2003; 5: 255-261
        • Grau A.
        • Buggle F.
        • Becher H.
        • et al.
        Recent bacterial and viral infection is a risk factor for cerebrovascular ischemia: clinical and biochemical studies.
        Neurology. 1998; 50: 196-203
        • Gorson K.
        • Pessin M.
        • Dewitt L.
        • et al.
        Stroke with sensory symptoms mimicking myocardial ischemia.
        Neurology. 1996; 46: 548-551