A. Brashear et Jc. Kincaid, THE INFLUENCE OF THE REFERENCE ELECTRODE ON CMAP CONFIGURATION - LEG NERVE OBSERVATIONS AND AN ALTERNATIVE REFERENCE SITE, Muscle & nerve, 19(1), 1996, pp. 63-67
Peroneal and tibial compound motor action potentials (CMAP) recorded u
sing the standard belly-tendon montage have different configurations.
The peroneal CMAP is a smooth dome shape, while the tibial CMAP has a
slow-rising initial component followed by a higher amplitude negative
peak. To evaluate possible causes of these differences we investigated
the individual activity recordable at the belly and tendon electrodes
by using a referential montage with the opposite foot as the referenc
e. This type recording shows that the peroneal belly site produces mos
t of the nerve CMAP, whereas the tendon site generates most of the hig
h tibial CMAP. Some features and technical problems of referential CMA
P recording using an opposite limb reference are shown. An alternative
method using an ipsilateral distal leg reference site is described, A
montage which separately records the activity at the belly or tendon
electrodes may provide new insight into mechanisms of commonly observe
d nerve conduction phenomena. (C) 1996 John Wiley & Sons, Inc.