Surface electromyography using electrode arrays: A study of motor neuron disease

The use of electromyography (EMG) is limited, particularly in the investiga tion of children, by the invasive nature of needle electrodes. Surface elec trode techniques are an attractive alternative but the detected signals are greatly influenced by volume conductor effects, thus making their interpre tation problematic. Using finite element analysis we investigated the relat ionship between surface potential distribution and motor unit depth, incorp orating anisotropic conductivity to model muscle tissue and a range of subc utaneous fat thicknesses. The modeling results were used to analyze data re corded with a 16-channel surface electrode array, from 10 normals subjects and 12 patients with motor neuron disease, Differences in the motor units b etween the two groups were statistically significant (P < 0.01) and are con sistent with reinnervation and increased motor unit territory in the patien t group. This noninvasive technique shows promise as a more acceptable alte rnative to the use of conventional needle electrodes for neurophysiological investigations. (C) 2001 John Wiley & Sons, Inc.