Somatosensory perception and cortical evoked potentials in established paraplegia

In 66 patients who suffered severe spinal cord injury 7 months to 28 years previously, somatosensory cortical evoked potentials were recorded to electrical stimulation of the leg nerves and compared to clinical assessment of light touch, pain, position sense and two-point discrimination. The patients were separated into 4 categories according to the degree of disintegration of the somatosensory evoked potential waveform. A clear correlation was found between the impairment of somatosensory perception and the deterioration of the somatosensory evoked potential in each group. However, it was not possible to observe any direct correlation between the sensory score or impairment of a single modality and somatosensory evoked potential changes, or among the impairment of single modalities on a case by case basis. This study indicates that the somatosensory evoked potential can be used to provide electrophysiological information independent of the clinical examination on functions of the dorsal columns in the chronic stage of spinal cord injury.