Disturbances of C-fibre-mediated sensibility in lumbosacral disc disease.

In nine patients with chronic lumbosacral disc disease and radicular symptoms clearly restricted to one leg, C-fibre-mediated sensibility was measured by determination of the thresholds for heat pain and warmth on the foot, ipsi- and contralaterally to the nerve root compression. The thresholds were compared with the values for 19 healthy subjects. In the patients the warmth threshold was increased in the ipsilateral dermatome and normal in the contralateral dermatome. In contrast, the heat pain threshold was near normal ipsilaterally but was clearly decreased contralaterally. These findings are discussed with respect to a possible pain sensitisation resulting from nerve root compression.