Estimation of motor unit territory using surface electrode arrays

Electrical signals from muscles can be detected by electromyography (EMG). They enable neuromuscular disorders to be diagnosed and the distinction between diseases of muscle (myopathy) and of nerve (neuropathy) to be made. The major drawback of EMG is that it requires the use of a needle electrode. The development of a non-invasive technique would have a major influence on the acceptability of EMG and its deployment in clinical neurophysiology. The effects of disease on motor units (MUs) (groups of muscle fibres, each supplied by a single motor nerve fibre) have been the focus of much research. Multi-electrode needle studies have demonstrated changes in the cross-sectional territory of MUs in different pathological states. We show here that it is possible to detect these changes in motor unit territory (MUT) using non-invasive surface electrode arrays.