A sensory level on the trunk in lower lateral brainstem lesions.

We report nine cases of vascular lesions in the lateral aspect of the lower brainstem. Five patients showed a sensory defect involving one side of the face and the contralateral leg, trunk, or both (crossed pattern). This contralateral defect involved the foot and extended upwards to end in a sensory level. Three other patients had a continuous hemisensory defect of the face, arm, and trunk (unilateral pattern), with the lower border demarcated at a sensory level. One patient had a combined pattern of both crossed and unilateral defects with sensory loss of the bilateral face and the unilateral limbs and trunk. Magnetic resonance imaging revealed lesions in the lateral pons and medulla in six cases. Far-lateral lesions were responsible for the crossed sensory defects, and mediolateral lesions resulted in the unilateral sensory defects.