Two-point discrimination thresholds in spinal cord injured patients with dysesthetic pain

We questioned whether deafferentation following SCI would result in an increase in somatic sensitivity possibly due to cortical reorganization. Dysesthetic pain syndrome (DPS) below the level of a spinal cord injury (SCI) is a common complication. We hypothesized that DPS patients would show increased cortical reorganization because of high levels of sensory stimulation following injury. Sixteen dysesthetic pain SCI patients, 15 SCI patients without pain, and 16 control subjects were examined for two-point discrimination thresholds (2PDT) of the forearm, neck, and spine. The SCI pain group had significantly smaller 2PDTs than either SCI no pain or control groups, particularly over the neck and spine. The SCI pain group had a significant inverse correlation between perceived degree of pain (visual analogue scale) and 2PDT in the spinal skin area. The findings indicate that SCI patients with severe DPS have a higher sensitivity to somatosensory stimuli, particularly in skin areas with projections to primary somatosensory cortex areas adjacent to the deafferentated region. The increase in 2PDT may be due to an increase in the size of the somatosensory cortical areas allotted to the corresponding skin areas.