Transient Ischemic Attacks: Diagnosis and Prognosis

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Abstract
The diagnosis of transient ischemic attacks (TIAs) is subject to considerable interobserver variation. One of the reasons may be that the diagnostic guidelines are phrased in abstract diagnostic terms such as amaurosis fugax, which require an interpretation of symptoms. The reliability of the diagnosis of TIA can be improved if the nature and time course of the symptoms are recorded in plain language. Another reason may be the arbitrary upper time limit of 24 h, while most clinical evidence suggests that TIAs and ischemic strokes should be regarded as a continuum rather than as separated subgroups. The overall risk of stroke or death in untreated TIA patients is approximately 10% per year. Recent studies have identified the following specific risk factors: increased age; male gender, multiple attacks; dysarthria; other vascular diseases, including diabetes, claudication, and angina, and the presence of various abnormalities on CT scan or electrocardiography. Patients with monocular visual symptoms only or vertigo as a main symptom have half the risk of patients with hemispheric attacks. The risk of stroke is specifically associated with an elevated hematocrit, and gradually increases with the duration of symptoms, independent of the classical ''boundaries'' at 24 h and 6 weeks which separate TIAs, reversible ischemic neurological deficits and strokes. Patients with symptoms atypical for a TIA may have a low risk of stroke but a high risk of major cardiac events. These findings underscore the need to (1) stratify patients with cerebral ischemia according to the risk of subsequent vascular events, especially in therapeutic trials, and (2) focus on the nature rather than the duration of symptoms.

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