Electromyography in Intraoperative Neurophysiological Monitoring: Principles, Applications, Guidelines and Clinical Relevance

Abstract

Electromyography is a central component of intraoperative neurophysiological monitoring because it gives the surgical team real-time information about motor nerves, nerve roots and muscles during procedures in which neural injury is a credible risk. Its clinical value lies not in a single waveform or threshold, but in the way electromyographic information is interpreted alongside anatomy, anaesthesia, surgical manoeuvres and other monitoring modalities. Intraoperative electromyography includes free-running recordings, triggered stimulation, cranial nerve mapping, laryngeal electromyography and muscle-recorded responses used within broader multimodal strategies. These techniques are applied in spinal instrumentation, nerve-root decompression, intradural spinal tumour surgery, vestibular schwannoma and skull-base surgery, thyroid and parathyroid surgery, and selected peripheral nerve operations. The method is highly useful for localising functional neural tissue and detecting irritation, but it is vulnerable to false-positive and false-negative findings when used without technical discipline or clinical context. This critical review examines the principles, applications, professional guidance and clinical relevance of intraoperative electromyography. It argues that electromyography should be understood as a decision-support tool rather than an isolated warning device. Its strongest role is in structured workflows where baseline testing, anaesthetic planning, alert verification, team communication and postoperative outcome audit are all treated as part of the monitoring intervention. Future progress will depend on better standardisation of reporting, more procedure-specific warning criteria, prospective studies linking alerts to surgical responses and patient outcomes, and careful integration of quantitative signal analysis with expert clinical judgement.