a These individuals contributed to the development of these guidelines during their tenure with the NHLBI Division for the Application of Research Discoveries. b These individuals contributed to the development of these guidelines during their tenure with American Institutes for Research (AIR).

SUMMARY In clinical usage, Wallenberg's lateral medullary syndrome has become synonymous with lateral medullary infarction due to occlusion of one of the rertebral or posterior inferior cerebellar arteries. We report a patient In whom the pathological process was demyeUnation. Stroke, Vol 12, No 6, 1981 A 51-YEAR-OLD, right-handed man was in good health until he noted the abrupt onset of difficulty in walking. Later the same day, he experienced slurred speech, vertigo, dysphagia and hiccups. He visited a physician the following day because of coughing, and "bronchitis" was diagnosed.On the third day of illness, he developed drooling from the right side of his mouth and "numbness" over the left side of his body. He was admitted to a local hospital where "evidence of cerebellar and brainstem dysfunction" was noted. A contrast-enhanced cranial CT-scan and lumbar puncture were normal. Ten days later the patient was transferred to the Denver Veterans Administration Medical Center for further evaluation.His general physical examination was within normal limits, including examination of the heart and extracranial blood vessels. Mental status was normal. Multiple abnormalities of head and neck function were noted. Pain and temperature perceptions were diminished on the left side of the face. There was weakness of the entire right side of the face. Speech was dysarthric and on phonation the palate deviated to the left. His tongue deviated slightly to the right on protrusion. There was a right Horner's syndrome. Strength was normal in all extremities. Pain and temperature perceptions were diminished over the left side of the body. Joint position and vibratory sensations were intact in the legs. Movement of the right upper extremity was ataxic. Gait was wide-based and marked by a tendency to fall to the right. Muscle stretch reflexes were normal, and plantar responses were flexor.The illness was complicated by recurrent aspiration pneumonitis and adult respiratory distress syndrome. Hypoxemia, hypotension and gastrointestinal hemorrhage developed, culminating in the patient's death 4 weeks after the onset of his symptoms. Neuropathological FindingsAt autopsy scalp, skull and meninges were unremarkable. The brain weighed 1,450 g and showed From the Departments of Pathology (Dr. Demasters) and Neurology (Dr. Smith), University of Colorado Health Sciences Center, Denver, CO.Reprints: Dr. Smith, Dept. Neurology, University of Colorado Health Sciences Center, 4200 E. Ninth Ave., Denver, CO 80262. normal configuration and vasculature. The vessels showed minimal atherosclerotic changes. Perfusion of the vertebral arteries in the neck showed good flow; no thrombosis could be detected in the right posterior inferior cerebellar artery. The spinal cord was not removed.On gross examination of multiple sections of brain, a single lesion was found. This consisted of an enlargement of the dorsal two-thirds of the right medulla.Microscopic sections of this region demonstrated a well-demarcated, rounded area of total demyelination which...