None of these trials clearly resolve the issue of whether to intervene in asymptomatic carotid stenosis. From these and other trials it can be inferred that it is uncertain if endarterectomy reduces the incidence of strokes in patients who have asymptomatic carotid stenosis with luminal narrowing that is less than 60 to 70 percent of normal diameter. For those with greater degrees of stenosis, the benefits are slight and may apply predominantly to older men. It is not clear if the presence of an ulcerated plaque or heavy calcification alters this view but it probably does not. These comments also apply to patients with asymptomatic carotid stenosis who are about to undergo major surgery such as cardiac bypass grafting, but adequate studies in this circumstance have not been performed. As already noted, any advice should be tempered by the surgical risk in a particular institution. Our usual practice with asymptomatic cases has been to start medical treatment with statin agents, accompanied by smoking cessation, aspirin therapy, and glucose control and to reevaluate the lumen of the internal carotid artery (using ultrasonography) at 6to 12-month intervals. If the stenosis is advancing or becomes narrowed to about 2 mm or less, or if there is an event that could be construed as a TIA referable to the stenotic side, then surgery or endovascular treatment is considered.
These comments reflect the guidelines for asymptomatic carotid stenosis set forth by the American Heart
Association in 2011 but there must be a careful evaluation of the circumstances in each patient, particularly the medical risk of endarterectomy, and a recognition that residual lumen diameters and percent stenoses are measured in different ways by varying techniques, both in the above-described studies and in clinical practice.
Course and Prognosis of Ischemic Stroke
It is a fair statement that no rules have yet been formulated that allow prediction of the early or late course of stroke. A mild paralysis may become a disastrous hemiplegia or the patient’s condition may worsen only temporarily. In cases of basilar artery occlusion, dizziness and dysphagia may progress in a few days to total paralysis and deep coma. Or, in both cases, the deficit may completely resolve. Anticoagulation and thrombolytic or endovascular therapy may alter the course but cerebral thrombosis is often progressive.
During the period 1970–1974 in Rochester, Minnesota, 94 percent of patients with ischemic strokes survived for 5 days and 84 percent for 1 month (Garraway et al, 1983a and b). The survival rate was 54 percent at 3 years and 40 percent at 7 years. These were significantly greater than had been the case during the period 1965–1969. These figures, which were gathered retrospectively, are comparable to more recent ones reported by Bamford and colleagues from patients who had strokes in the 1980s. The mortality rate following cerebral infarcts (no separation being made between thrombotic and embolic types) at the end of 1 month was 19 percent and at the end of 1 year, 23 percent. Of the survivors, 65 percent were capable of an independent existence. In every series, among long-term survivors, heart disease is a more frequent cause of death than additional strokes. It has been repeatedly pointed out that pneumonia as a result of disordered swallowing is a major determinant of survival; further discussion regarding aspiration problems following stroke are found in later sections of the chapter.