Motor and sensory evoked potential studies in brainstem strokes.

To document evoked potential changes in brainstem strokes, motor evoked potential (MEP) to abductor digiti minimi and median somatosensory evoked potential (SEP) were studied in 10 patients with medial and four patients with lateral brainstem strokes. All the patients with lateral brainstem stroke had normal MEP; and SEP was abnormal in one only. In medial brainstem stroke patients, MEP was abnormal in seven; unrecordable in 4 and prolonged central motor conduction time in 3 patients. SEP was abnormal in four; unrecordable in 3 and prolonged central sensory conduction in 2 patients. In one of these patients SEP was unrecordable in one and delayed in other side. Motor evoked potential abnormality was consistent with medial brainstem stroke and predicted a poor outcome.