Infarct Size May Distinguish the Pathogenesis of Lacunar Infarction of the Middle Cerebral Artery Territory

BACKGROUND Lacunar infarctions are caused by small vessel disease (SVD) and branch atheromatous disease (BAD). Lacunar infarction may be classified as proximal vessel lacunar infarction (BAD) or distal vessel lacunar infarction (SVD) according to its location within the middle cerebral artery (MCA) territory in patients with normal MCA. Studies found that the lenticulostriate arteries may exist different ways and that the size of lacunar infarction may be dependent on the branching order. We investigated whether lacunar infarction size can differentiate between SVD and BAD in patients with normal MCA. MATERIAL/METHODS We retrospectively studied 312 patients with lacunar infarction who had normal MCA on MR angiography. We found the normal flow void of the MCA on MR T2-weighted images, and the same layer on DWI was considered the level 0. The median of lowest layer of infarction lesions and the mean of lesion size were considered the cutoff point. We divided lacunar infarction into 2 groups according to cutoff point of lesion location and size. Data compared between the 2 groups included clinical information, radiography, and National Institutes of Health Stroke Scale score. RESULTS Of all the 312 patients, the median of lowest layer of infarction lesions was the 3rd level. Compared to patients with BAD, according to infarct location, patients with SVD were older, more often had a history of hypertension and smoking, and had more severe leukoaraiosis and smaller infarct lesions. The mean length of lesions was 11.1 mm on DWI images. Patients with SVD, according to infarct size, had lower NIHSS scores at admission. The mean lesion height was 12.26 mm on FLAIR images. Patients with SVD were more often male, had higher prevalence of smoking, and had more severe leukoaraiosis and lower NIHSS scores at admission. The lacunar infarction diameter on DWI and FLAIR images was negatively correlated with the level of lowest layer of infarction lesions. CONCLUSIONS Our data suggest that infarct lesion size may be used as a method to distinguish SVD and BAD in lacunar infarction patients with normal MCA.