The side and somatotopical location of single small infarcts in the corona radiata and pontine base in relation to contralateral limb paresis and dysarthria.

The aim of this study was to investigate whether the side and location of single small infarcts (< or = 3 cm) in the corona radiata (28 patients) and pontine base (36 patients) influence the incidence of contralateral upper or lower limb paresis and dysarthria. While the severity of contralateral limb paresis was not significantly different between right and left corona radiata lesions, infarcts presenting with contralateral limb paresis and/or dysarthria presented significantly more often in the left than in the right hemisphere, and left infarcts were significantly smaller than right infarcts. Lesions related to dysarthria and upper and lower limb paresis were arranged anterior-posteriorly in the paraventricular corona radiata region. Pontine base infarcts presenting with dysarthria also presented significantly more often in the left than in the right pons. Dysarthria showed a significant correlation with lesions presenting in the dorsomedial portion of the pontine base, upper limb paresis with those in the dorsomedial and dorsolateral portions, and lower limb paresis with lesions in the ventromedial portion. These results suggest greater influence of the left descending motor fibers on contralateral limb movement and articulation than of the right and face-arm-leg somatotopy of motor fibers in the paraventricular corona radiata region (anteroposterior) and in the pontine base (dorsoventral).