Electrophysiological methods for estimation of the number of motor units

Abstract

Various neurological diseases involving motor neurons or their axons lead to decrease in the number of functioning motor units (MU). Counting the number of intact MUs plays significant role in assessing the progression of the pathological process associated with motor neuron death. Quantitative estimation of MUs using routine electromyography methods is usually impossible. Therefore, electrophysiological methods for estimation of the number of MUs, currently known under the common name MUNE (motor unit number estimation), are being discovered over the past decades. The first publication on MUNE was issued in 1971. Since that time, promising, more accurate, and less time-consuming modifications have been developed, and new MU counting methods have been proposed. In recent years, we can see increasing interest in MUNE in connection with the search for new treatments for motor neuron disease, assessment of their effectiveness, and dynamic control of the disease. Today, MUNE is considered as a potential biomarker in clinical trials of new treatments for motor neuron disease. This review presents the available MUNE techniques, describes their comparative characteristics, advantages and disadvantages of each method, and discusses the experience and prospects of their application.

Keywords

• motor units
• electromyography
• mune
• motor neuron disease