[Pure sensory stroke due to a pontine lesion: a study of clinical symptomatology and somatosensory evoked potential findings].

We studied clinical symptomatology and somatosensory evoked potentials(SEP) of 7 pure sensory stroke patients due to pontine lesions. Clinical symptoms were examined by modality(pinprick, touch, vibration and joint position sense), intensity and distribution of the sensory disturbance. SEP were recorded by the median nerve stimulation in the upper extremities, and the posterior tibial nerve stimulation in the lower extremities. Patients 1-4 were characterized by decreased contra-lesional fingers or fingers, toes joint position sense, normal pinprick and vibration sense. We think that these patients' lesions were localized in the lemniscus medialis. Patients 5-7 were characterized by decreased contra-lesional upper extremity or upper and lower extremity vibration sense, decreased pinprick sense and normal joint position sense. We think that these patients' lesions involved spinothalamic tract. There was no abnormal finding of SEP with upper extremity stimulation, but disappearance or very low amplitude of P38 with lower extremity stimulation in 4 of the 7 patients. We conclude that 1) the vibration sense may be conducted also through the spinothalamic tract, 2) SEP findings are abnormal only with lower extremity stimulation in pontine pure sensory infarction.