Destructive brain lesions that occur early in development are often unilateral or asymmetric. We analyzed the lateralization of lesions among a previously reported series of 51 patients with three kinds of destructive lesions based on their topography: specific arterial territory (AT), arterial borderzone territory (Bdz), hemispheric (H). Five patients (all from group Bdz) had bilateral nonlateralizing lesions. The distributions of left- and right-sided lesions were distinct among the groups (P=0.014): in group H, all patients except one presented with right-sided lesions (89%); in group Bdz, left-sided lesions (53%) were more frequent than right-sided lesions (17.7%); in group AT, left- and right-sided lesions were more equally distributed (56 and 44%). Our study suggests that there is a trend toward lesion lateralization among patients with different patterns of precocious destructive lesions. Differences in cerebral maturation and vulnerability between the hemispheres is a possible factor explaining lesion lateralization in early life insults.51014-6