Clinical-computed tomographic correlations of lacunar infarction in the Stroke Data Bank. Lacunar stroke was diagnosed in 337 (26%) of the 1,273 patients with cerebral infarction among the 1,805 total in the Stroke Data Bank. We analyzed the 316 patients with classic lacunar syndromes. Among these, 181 (57%) had pure motor hemiparesis, 63 (20%) sensorimotor syndrome, 33 (10%) ataxic hemiparesis, 21 (7%) pure sensory syndrome, and 18 (6%) dysarthria-clumsy hand syndrome. No striking differences were found among the risk factors for the lacunar subtypes, but differences were found between lacunar stroke as a group and other types of infarcts. Compared to 113 patients with large-vessel atherosclerotic infarction, those with lacunar stroke had fewer previous transient ischemic attacks and strokes. Compared to 246 with cardioembolic infarction, patients with lacunar stroke more frequently had hypertension and diabetes and less frequently had cardiac disease. We found a lesion in 35% of the lacunar stroke patients' computed tomograms, with most lesions located in the internal capsule and corona radiata. The mean infarct volume was greater in patients with pure motor hemiparesis or sensorimotor syndrome than in those with the other lacunar stroke subtypes. In patients with pure motor hemiparesis and infarcts in the posterior limb of the internal capsule, there was a correlation between lesion volume and hemiparesis severity except for the few whose infarct involved the lowest portion of the internal capsule; in these patients severe deficits occurred regardless of lesion volume. Taken together, the computed tomographic correlations with the syndromes of hemiparesis showed only slight support for the classical view of a homunculus in the internal capsule. 