Electrophysiological assessment of focal nerve lesions

A technique is described for quantitatively characterizing focal lesions in peripheral nerves. At the lesion site, conduction fails in some fibers and is abnormally delayed in others. The technique computes the fraction of conducting fibers and the distribution of added delays (DAD). Compound action potentials (CAPs) are evoked by stimulating distally and proximally to the lesion. Then, using a model of the CAP as a sum of single-fiber action potentials, the distribution of conduction velocities (DCV) and the DAD are computed. The method can be applied to surface-recorded CAPs as well as monophasic CAPs recorded using the crushed-nerve technique. The authors applied the DAD technique to evaluate three methods of nerve repair. They found that the conduction fraction was the same for all three methods, but that a fascicular suture method had a significantly lower average added delay.<
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