An electrophysiological method to assess the distribution of the sensory propagation velocity of the digital nerve in normal and diabetic subjects

We report a new computer-assisted collision method to evaluate sensory conduction velocity (SCV) distribution in the digital nerve of the middle finger in normal subjects and in insulin-dependent diabetic subjects without any neurological impairment. Distribution curves were monomodally shaped in controls, indicating a greater proportion of fibers with relatively slow conduction velocity and a lesser proportion of fibers with faster velocity. In most diabetic nerves, a monomodal trend of the SCV distribution indicated a definite reduction in high and intermediate SCV. In a small proportion of nerves, the SCV distribution tended to be bimodal, with an absolute maximum corresponding to lower velocities and a relative maximum to intermediate-fast velocities. Slowing of the intermediate velocity, or loss of fibers of intermediate velocity, can be hypothesized to represent the early electrical evidence of a subclinical polyneuropathy in insulin-dependent diabetic subjects.