[Stroke Mimics and Stroke Chameleons: Differential Diagnosis of Stroke].

The analysis of misdiagnosis of stroke has become increasingly relevant because of the time pressure in the thrombolytic treatment of ischemic strokes. Within the narrow time window of thrombolysis, a false-positive stroke diagnosis can lead to a faulty and potentially dangerous thrombolysis. The terms "Stroke Mimic" (SM = false-positive stroke diagnosis) and "Stroke Chameleon" (SC = false-negative stroke diagnosis) have been introduced for misdiagnosis in this field. The rate of SM decreases during the treatment phases from approximately 50 % in the preclinical situation to approximately 2-10 % in the Stroke Unit indicating thrombolytic therapy. The complication rate for not indicated thrombolysis in SM is low with 0.5 % for intracranial bleeding and 0.3 % for orolingual edema. Thus, the net balance in favour of fast thrombolysis is maintained, even when a higher number of mis-indicated lyses occurs in SM. The rate of SC during the stages of treatment drops from about 50 % in the preclinical stage to about 2-5 % in stroke units. The rates of SM and SC are inversely linked: a reduction in the SM rate leads to a more critical diagnosis of stroke, thus increasing the number of underdiagnosed stroke cases as SC, and vice versa. While SM rarely lead to the legal consequences of treatment error, SC often give rise to accusations of medical errors.