Some stroke experts defined TIA is a brief neurological dysfunction induced by a focal brain or retinal ischemic lesion, whose symptoms last in general close to one hour without any infarction in the neuroimaging4. Twothirds of TIAs last less than 1 hour and the probability that symptoms lasting more than 1 hour disappear within 24 hours is 15%4. In addition the
prevalence of ischemic lesions on MRI increases with symptom duration.
Although classic definition of TIA may induce a delay in thrombolysis therapy, however classic definition has epidemiologic points of interest.