[Pure sensory hemisyndromes caused by infarctions in the pons]

This study reports 3 cases of pure hemisensory syndrome due to lacunar infarction at the pons, demonstrated by magnetic resonance. In all patients somatosensory evoked potentials were abnormal. In two out of the 3 cases these potentials remained abnormal even after clinical exploration normalized. Due to the distribution of the sensitive pathways it may be assumed that the hemisensory syndrome would be caused by lesions located from the cortex to the pons. By means of clinico-pathological correlations the hemisensory syndrome was attributed to lesions exclusively located at the cerebral cortex or at the thalamus. However, in 1984 the first case of hemisensory syndrome due to pontine infarction was demonstrated by computerized tomography. After this report a series of approximately 10 patients have been published in the english and french literature. None of them had data on somatosensory potentials. In our experience the study of somatosensory evoked potentials has a high sensitivity. It appears that the distribution of the sensitive defect is independent of the location of the structural lesion.