[Transient ischemic attack: past, present, and future].

Transient ischemic attack (TIA) is a brief episode of reversible neurological deficits caused by focal and temporary central nervous system ischemia. TIA is associated with a high risk of recurrent ischemic stroke, but immediate evaluation and intervention for TIA lowers this risk of recurrent ischemic stroke. A new clinical concept termed acute cerebrovascular syndrome (ACVS) that includes TIA and acute ischemic stroke has been proposed. With the development of new neuroimaging modalities such as diffusion-weighted image (DWI), the definition of TIA used in the United States has shifted from time-based (less than 24 h) to tissue-based (without acute infarction). High ABCD² score, carotid artery stenosis, and DWI lesions suggest that patients are at a high risk for early recurrence of ischemic stroke. Recently, it was reported that not only DWI or magnetic resonance angiography(MRA), but also fluid-attenuated inversion recovery (FLAIR) images are useful for evaluating TIA. In Japan, the definition of TIA has not been revised since 1990. To review the definition of TIA and establish a TIA management system that is suitable to domestic healthcare environment, the Japan TIA research group (PI, Kazuo Minematsu) was formed in 2009. The group conducted a nation-wide survey and a retrospective registration study to clarify the current status of clinical practice of TIA. In the group's opinion, TIA is defined as the presence of focal neurological symptoms ascribable to a vascular etiology lasting less than 24 h, irrespective of imaging findings, as classically defined. However, if acute ischemic lesions are found on DWI, it is diagnosed as "TIA with DWI lesions." The group also made recommendations for hospitalization policies and outpatient management.