Predisposing factors for cerebral infarction: the Oxfordshire community stroke project.

The frequency of known causative factors of cerebral infarction was studied in 244 cases of first ever stroke due to cerebral infarction proved by computed tomography or at necropsy who were registered in the first two years of a prospective community based study. Risk factors for cerebral infarction were present in 196 (80%) cases; hypertension in 126 (52%); ischaemic heart disease in 92 (38%); peripheral vascular disease in 60 (25%); a cardiac lesion that was a major potential source of embolism to the brain in 50 (20%); transient ischaemic attacks in 35 (14%); cervical arterial bruit in 33 (14%); and diabetes mellitus in 24 (10%). Thirty one patients (13%) were in atrial fibrillation. Of the 48 patients who were free of risk factors or a major potential cardiac source of embolism at the time of the stroke, 18 were found to have hypertension after the stroke and 10 to have non-atheromatous non-embolic conditions (migrainous cerebral infarction (three), arteritis (two), inflammatory bowel disease (one), arterial trauma (one), autoimmune disease (one), carcinoma of the thyroid (one), and major operation (one). In 20 patients no causative factors could be identified. In this unselected series of patients with first ever stroke due to cerebral infarction most of the strokes were presumed to be due to either atheromatous arterial disease or embolism from the heart, and only 4% (95% confidence interval 2 to 7%) were probably due to non-atheromatous non-embolic causes. This has implications for research into strokes and allocation of public health expenditure.