[Transient ischemic attacks in the elderly: new definition and diagnostic difficulties]

Abstract

Transient ischemic attacks (TIA) are very frequent in the elderly. Their frequency increases beyond 65 years. However, no epidemiologic study was specifically dedicated to elderly patients. The first definition of TIA was a sudden focal neurologic deficit that lasted for less than 24 hours, presumed to be of vascular origin and located in a specific artery territory of the brain or eye. The Working Study Group has proposed a new definition: TIA is a brief episode of neurologic dysfunction caused by focal brain or retinal ischemia with clinical symptoms typically lasting less than one hour, most often some minutes, and without evidence of acute infarction. Weighted diffusion MRI may show very early an aspect of cytotoxic oedema. The one-hour criterion associated with a stable neurological deficit is requested for initiating IV thrombolysis, if the angio-MRI shows an occlusion of the supra-aortic trunks or intracranial arteries, even in aged patients. Each TIA constitutes a major risk for a completed infarct resulting in disability or death. Hypertension is the main risk factor for TIAs, followed by atrial fibrillation, diabetes, coronaropathy and sedentarity. These factors multiply by 4 the stroke risk. In the elderly, TIAs are pecularly associated with lacunar infarcts in the territory of deep perforating arteries. TIAs represent a neurologic emergency that allows no delay in clinical and laboratory investigations, such as ultrasonic echographies and weighted diffusion MRI. Diagnostic errors are often due to frequent polypathology and cognitive changes in great age. The most misleading symptoms are vertigo, imbalance, falls, disorders of consciousness. Unawareness of the deficit is also a frequent cause of failure of TIA diagnosis. Conversely, the most frequent cause of diagnostic error by excess is epileptic seizures which are often under-evaluated.