Temperature sensitivity of some nerve conduction parameters in diabetic polyneuropathy

We tested whether in diabetic polyneuropathy the temperature dependence of the median nerve conduction parameters reflects the severity of neuropathy.

We validated an electrophysiological score against clinical signs of polyneuropathy. Electroneurography was performed at temperatures from 20-40 degrees C in diabetic patients with mild, moderate and severe neuropathy and controls.

The electrophysiological score reflected the clinical severity of polyneuropathy. At room temperature there were significant differences among groups in almost all parameters. In thermal sensitivity studies were significant differences in distal and proximal motor and sensory areas and in sensory conduction velocities. These four parameters normalized to 1 degree C change in temperature also significantly differed among the four groups and were largest in controls and smallest in severe polyneuropathy.

The use of an integral parameter--areas are essentially amplitudes integrated over time--increases the probability of detecting decreased thermal sensitivity of peripheral nerves in diabetes.