Progressive cerebral ischemia antedates cerebrovascular symptoms by two years.

Prospective longitudinal cerebral blood flow values were serially plotted over a four-year interval against the course of cerebral ischemia before, during, and after onset of clinical symptoms. Of 161 normal subjects (mean age, 62 years), 86 were risk free and 75 had hypertension, heart disease, diabetes mellitus, and/or hyperlipidemia. Twenty-one subjects developed cerebrovascular symptoms during the prospective trial. Mean hemispheric cerebral blood flow values were significantly lower for at risk than for risk-free subjects. Symptomatic subjects showed lower values than those in either of the two asymptomatic groups at every session. Statistical analysis of cerebral blood flow values for symptomatic patients compared one and two years prior to onset of symptoms, at the onset of symptoms, and 1 year later showed reductions compared to asymptomatic risk-factored subjects tested in a similar prospective manner. Measurable declines in cerebral perfusion accompany development and progression of aortocerebral atherosclerosis prior to clinical appearance of signs and symptoms of cerebrovascular disease. If confirmed, these observations should permit the institution of preventive medical and/or surgical interventive measures and an evaluation of their outcome.