Transient cerebral ischemia: Definition and natural history

Abstract

N considering cerebral &hernia and infarction there are so many interrelating clinical and pathophysiologic phenomena that a standard set of definitions or reference language should be used and understood by practicing clinicians and clinical investigators alike. When the term “transient ischemic attack” (TIA) is used, does it, for instance, mean only symptoms of a focal neurologic deficit, or does it include symptoms of diffuse cerebral ischemia (syncope), and does it include common complaints such as dizziness and vertigo? Precision in definition is all important in defining the natural history of the disorder to determine if TIAs are a high risk factor in the stroke-prone profile. The difficulties are emphasized by the report in 1964 of one clinical investigator’ who found a stroke rate of 2% in patients with transient ischemic attacks who were observed for 45 mo. The next year the same investigator’ reported a stroke rate of 43% in 158 patients with TIA observed for 60 mo. This important difference in the two