Abstract
We report a case of lacunar infarction of the lateral lower medulla, showing rt. Horner's syndrome, hypalgesia under Th11 and thermohypoesthesia under Th10 on the right and truncal ataxia. CT scan revealed no obvious findngs in the brain stem, but MRI demonstrated a lacunar infarction in the lateral lower medulla. It was shown that segmental dissociated sensory disturbance without sensory deficit in the face could be caused by partial impairment of the lateral spinothalamic tract, which is arranged with the fibers from the sacral segments most lateral. Although segmental sensory disturbance is usually thought to be a sign of spinal cord disease, it is important that such sensory disturbance can also appear in patients with disease of the brain stem.
