Correlation of sensory electroneurographic recordings and myelinated fiber diameters of the superficial peroneal nerve of dogs.

The compound nerve action potential (CNAP) of the superficial peroneal nerve of dogs was investigated to determine: (1) the influence of the stimulation technique on the configuration of the CNAP, with particular attention to late components; (2) the fiber diameter (FD) distribution; and (3) the relationship between FD distribution and CNAP configuration, by reconstruction of CNAP made on the basis of FD distributions. The CNAP were evoked in 9 dogs under halothane anesthesia by 2 stimulation methods: percutaneous needle electrode stimulation and direct stimulation of the exposed superficial peroneal nerve. Recordings were made with percutaneous needle electrodes. Full nerve cross sections of 7 superficial peroneal nerves were prepared for FD morphometric analysis. Reconstruction of CNAP were made on the basis of the FD distributions. Late components of the CNAP could be evoked with either stimulation method, but only with a stimulus intensity of 3 to 5 times maximal for the main (early) component of the CNAP. The FD histograms of 7 analyzed nerves had bimodal distribution. In 5 nerves, peaks were at 4.2 to 4.5 microns and 9.0 to 10.0 microns, with 60% of the fibers in the small-diameter group. In 2 nerves with lower maximal conduction velocities, peaks were shifted toward smaller values. The CNAP reconstructions made by use of FD data closely resembled actual recordings when a fifth-order polynomial function was applied to the relationship between nerve conduction velocity and FD. Reconstructions made by use of 1 or 2 linear functions did not accurately resemble actual recordings.(ABSTRACT TRUNCATED AT 250 WORDS)