| ORIGINAL RESEARCH (2008) | |||||||||||||
Abstract | |||||||||||||
| Brain imaging has challenged the assumption that because clinical transient ischemic attack (TIA) symptoms resolve, significant ischemic tissue does not occur. 1-4 MR imaging using diffusion-weighted imaging (DWI) reveals an ischemic lesion in approximately half of all TIAs (range, 21%– 67%), 1,4-11 with the probability of DWI positivity increasing with the duration of symptoms. 7,12 Therefore, the TIA Working Group has proposed a new definition of TIA as a brief episode of neurologic dysfunction presumptively caused by focal brain or retinal ischemia, with clinical symptoms typically lasting less than 1 hour, and without neuroimaging evidence of acute infarction. The corollary is that persistent clinical signs or characteristic imaging abnormalities define infarction—that is, stroke. 3 This implicitly assumes that imaging changes associated with these transient focal neurologic | |||||||||||||
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