Sensory dermatomal representation in the medial lemniscus

Background: Restricted sensory deficits along the somatotopic topography of the medial lemniscus rarely develop in medial medullary infarction. We des cribe a patient with medial medullary infarction who presented with dermato mal sensory deficits caused by a medial lemniscal lesion. Case Description A 58-year-old man presented with sudden right-sided hemipa resis and paresthesia. He had noticed the paresthesia below the level of th e right L5 dermatome, where his vibration and position senses were mildly d iminished. This paresthesia was more severe over the right calf and foot. M agnetic resonance images of the brain showed an acute small infarct in the medial- ventral portion of the left rostral medulla oblongata. A nerve cond uction study and electromyography showed no abnormalities. At follow-up, th e patient's motor and sensory deficits had improved considerably. Conclusions: The patient showed lemniscal sensory deficits below the right L5 dermatome that were caused by the partial involvement of the medial lemn iscus. These findings suggest that lemniscal sensory dermatomal representat ion is preserved at least up to the level of the medulla oblongata.