Concerning transient ischemic attacks1
To investigate some of the controversies concerning transient ischemic attacks (TIAs) recent experience with cerebrovascular disease at the Massachusetts General Hospital is reviewed. For example, TIAs are commonly thought to last up to 24 hours, but TIAs rarely lasted one hour in Massachusetts General cases (135 cases). Recurrent TIAs preceded strokes in 90% of 100 cases, whereas single TIAs usually posed no threat (32 cases). Of 80 patients who had more than one TIA, 88.5% had the second attack within one week. A clinicopathologic study of endarterectomy specimens in 57 cases supported hemodynamic failure rather than embolism as the cause of TIAs. Embolism from a carotid mural thrombus caused longer spells (1 case). Cardiogenic emboli (200 cases) entering a carotid system did not cause ischemic episodes that mimicked carotid TIAs (50 cases), that is, their behavior did not resemble that attributed to fibrin platelet emboli from carotid mural thrombi. The problem of TIAs in the absence of vascular disease is discussed.