Averaging techniques to define the low-amplitude compound motor action potential

Patients with disorders in which the very distal musculature is markedly atrophic and the slightly more proximal musculature is fairly well preserved present the electrodiagnostician with the occasional problem of electrokinetic and, to a lesser extent, volume-conduction artifacts completely obscuring the proximally evoked compound motor action potential. Firm restraint of the arm usually resolves this problem. However, if this is unsatisfactory, or for various reasons cannot be fully applied, averaging may be a useful adjunt. It is not a substitute for good technique.