A new definition of transient ischemic attack (TIA) was proposed by the working group of the American Heart Association and the American Stroke Association in 2009. In this definition, TIA is defined as a transient episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischemia, without acute infarction. This definition is currently much argued, and has not yet been globally accepted. There would be no meaning to differentiate TIA from ischemic stroke only by the duration of symptoms. Because, TIA in acute setting and acute ischemic stroke share the same spectrum. Therefore, we proposed a new clinical concept termed acute cerebrovascular syndrome (ACVS), which includes acute TIA and acute ischemic stroke. Patients early after TIA are at high risk of stroke and thus should be immediately evaluated and treated as a medical emergency, that is, ACVS. An international multicenter cooperative registry study is ongoing in 5,000 patients with TIA or minor stroke within 7 days after the onset, who will be followed up for 5 years, involving Japanese patients.
