Variation in risk factors for recent small subcortical infarcts with infarct size, shape and location

Background and Purpose
Lacunar infarction is due to a perforating arteriolar abnormality. Possible causes include embolism, atheromatosis or intrinsic disease. We examined whether the size, shape or location of the lacunar infarct varied with embolic sources, systemic atheroma or vascular risk factors.

Methods
We examined data from three prospective studies of patients with clinical and diffusion-weighted imaging (DWI) positive symptomatic lacunar infarction who underwent full clinical assessment and investigation for stroke risk factors. Lacunar infarct size (maximum diameter; shape, oval/tubular; location, basal ganglia/centrum semiovale/brainstem) were coded blind to clinical details.

Results
Amongst 195 patients, 48 infarcts were tubular, 50 were 15-20mm diameter, 97 were in the basal ganglia and 74 in the centrum semiovale. There was no association between infarct size or shape and any risk factors. Centrum semiovale infarcts were less likely to have a potential relevant embolic source (4% v 11%, OR 0.16 95% confidence interval (CI) 0.03-0.83) and caused a lower National Institute of Health Stroke Scale (NIHSS) (2 v 3, OR 0.78 95% CI 0.62-0.98) than basal ganglia infarcts. There were no other differences by infarct location.

Conclusions
Lacunar infarcts in the basal ganglia caused marginally more severe strokes and were three times as likely to have a potential embolic source than those in the centrum semiovale but the overall rate of carotid or known cardiac embolic sources (11%) was low. We found no evidence that other risk factors differed with location, size or shape suggesting that most lacunar infarcts share a common intrinsic arteriolar pathology.