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Abstract Recent advances in neuroimaging have enhanced the understanding of TIA. Accumulated evidence indicates that clinically transient manifestations are not transient at the tissue level and leave infarction in the brain in about half of TIA patients. TIA-related acute infarcts are typically extremely small and often are not detected by CT and conventional MRI. Diffusion-weighted imaging (DWI) is currently the preferred method of imaging in TIA. Recognition of acute infarcts in patients with TIA has challenged the long standing conventional definition and led to the proposition of a new tissue-based definition. The tissue based definition reserves the term TIA for transient episodes without radiological evidence of acute infarction. So that “TIA with DWI related lesions” represents an extremely unstable condition with early risk of stroke that is higher than the risk after TIA with normal imaging. The persons of this study were classified in to 2 groups; patients group (Ι) and control one (Π). The patients group (Ι) was divided in to 2 subgroups: 1-Group (ΙA): (n=35) were those clinically diagnosed to have a recent TIA for the first time for whom initial DW-MRI scans were done within 48 hr from TIA onset and a follow up one 3 months later for those with initial positive DWI. 2- Group (ΙB): (n=35) were those clinically diagnosed to have a recent ischemic cerebro-vascular stroke with past history of TIAs during the last one year. In group (ΙA), it was found that those with TIA duration ≥1 hour, having mainly AF and /or carotid artery stenosis > 50% and clinically presented with aphasia and/or motor manifestations were associated with lesions on Summary 105 DWI and the combinations of two or more previous parameters were associated with irreversible lesions on follow up DWI done 3 months later from the initial ones. In group (ΙB), it was found that most of the clinical presentations of the acute ischemic strokes were similar to that of prior TIAs whom those patients had during the last one year with ipsilateral hemispheric involvement. It was also found that DWI done during development of evident ischemic stroke detected permanent ischemic lesions corrosponding to the prior TIAs manifestations in 8 patients (22.85 %). Those with prior TIAs duration ≥ 1 hour , having mainly AF and /or carotid artery stenosis > 50% as risk factors and clinically presented with aphasia and/or motor manifestations , had positive DWI for their prior TIAs more than those with negative scans. |