Significance of white matter high intensity lesions as a predictor of stroke from arteriolosclerosis

To determine whether the extent of white matter high intensity lesions (WML) on magnetic resonance imaging (MRI) is an independent predictor of risk for stroke from arteriolosclerosis, and whether serial evaluation of WML can be used to identify patients who are at risk of strokes.

Prospective follow up with serial MRI scans was done in 89 patients who were either diagnosed as having symptomatic lacunar infarcts or were stroke-free, neurologically normal individuals with headache or dizziness. None had significant stenosis of major cerebral arteries or atrial fibrillation. Multivariable analysis with the Cox proportional hazards model was used to test the predictive value for subsequent stroke of risk factor status at entry and during follow up, lacunar infarction, and the extent of WML (scored from 0 to 16) on the baseline scans.

During follow up (mean (SD), 51 (19) months), seven strokes occurred (five lacunar infarcts and two haemorrhages): four in nine patients with severe WML (score 9-16), and three in 40 patients with mild WML (score 1-8) (log-rank test; p < 0.005). None of 40 patients without WML experienced stroke. The extent of WML was an independent predictor of subsequent stroke (relative risk for a 1 point score increase, 1.60; 95% confidence interval, 1.02 to 2.54; p < 0.05). In three strokes among 80 patients without severe WML, two occurred in four patients with an increase in WML score during follow up, and one occurred in the other 76 patients without an increased score (p < 0.0001).

Severe WML at baseline is an independent predictor of risk for stroke from arteriolosclerosis, while progression of WML during follow up may be associated with subsequent stroke in patients with initially mild WML.