View source for Clinic Electromyography

{{main menu}}

{{ArtBy|||autore= Cesare Iani}}

'''Abstract:''' In this chapter on clinical electromyography (EMG), we explore the fundamental principles and advanced techniques used to assess motor unit (MU) activity. This section offers a detailed examination of the three primary phases of an EMG exam: spontaneous activity, motor unit analysis, and interference pattern (IP) analysis. The motor unit, comprising a motor neuron, its axon, and innervated muscle fibers, is the focal point of the examination. We delve into the nuances of different electrodes—single fiber, macro, concentric, and monopolar—and their respective advantages and applications.

The generation and analysis of motor unit potentials (MUPs) are critical for diagnosing neuromuscular disorders. MUP parameters such as duration, amplitude, size index, and jiggle are discussed in relation to normal and pathological conditions. Advances in EMG technology, particularly in signal decomposition and template matching, have allowed for more efficient and accurate analysis of MUPs, contributing to improved diagnostic capabilities in both neuropathic and myopathic disorders.

The chapter also covers interference pattern (IP) analysis, focusing on recruitment and frequency modulation as physiological correlates of muscle contraction. Methods for quantifying and interpreting IP signals, including time-domain analysis and the turns/amplitude analysis method, are presented. Recent advances, such as Cloud analysis, provide a visual representation of normal and abnormal patterns in myopathies and neuropathies, further enhancing the diagnostic value of EMG.

In conclusion, this chapter emphasizes the importance of precise signal acquisition, analysis, and interpretation in clinical electromyography, offering valuable insights for the diagnosis and management of neuromuscular conditions.