Analysis of conduction velocity in the H pathway. Part 2. An electrophysiological study in diabetic polyneuropathy

The conduction velocity in the different partial segments of the monosynaptic pathway of the lower limbs has been assessed in 50 unselected diabetic patients in order to evaluate the distribution of conduction slowing in the entire course of peripheral nerves in the most common form of polyneuropathy. According to the method previously described (Troni 1981), the conduction velocity in the entire course (popliteal fossa-to-spinal cord), in the proximal segment (buttock-to-spinal cord) and in the distal segment (pf-to-buttock) of the H pathway, has been determined and expressed by mixed (sensory-motor) conduction indexes. Moreover, the conduction velocity of the 1a afferent and of the motor fibres, has been selectively evaluated in the pf-to-buttock segment. The comparison between the impairment of each partial conduction parameters proves the existence of a clear-cut proximo-distal gradient of conduction slowing in the H pathway in diabetic polyneuropathy. Marked slowing in the larger-diameter 1a afferent fibres can also be demonstrated in the pf-to-buttock segment.