Invited Review: Utility of laryngeal EMG for establishing prognosis and individualized treatment after laryngeal neuropathies-Article

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This review by Libby J. Smith DO and Michael C. Munin MD emphasizes the importance of laryngeal electromyography (LEMG) in diagnosing and treating laryngeal neuropathies. LEMG helps assess neuropathic injuries to the recurrent laryngeal nerve (RLN) and superior laryngeal nerve (SLN), which are essential for vocal fold (VF) movement. Disorders in VF motion can severely affect a patient's voice, swallowing, and breathing, compromising quality of life.<br /><br />LEMG provides a detailed prognosis for VF motion recovery by characterizing the extent of neuropathic damage. It is especially crucial for cases resulting from surgeries around the skull base, neck, or chest due to the complexity of the RLN's path. The review highlights current techniques to enhance the predictive values of LEMG including the assessment of laryngeal synkinesis and quantitative analysis.<br /><br />Synkinesis involves unintended reinnervation leading to unwanted VF motion. Diagnosing it requires observing motor unit potential variations during different tasks. Quantitative LEMG analysis, such as turns analysis, adds objectivity by measuring motor unit recruitment rates, generally establishing normal values around 400 turns/second.<br /><br />LEMG is conducted efficiently through teamwork between electromyographers and otolaryngologists, ensuring precise diagnosis and individualized treatment planning. This may include watchful waiting, temporary VF augmentation, or more definitive procedures like medialization or reinnervation based on LEMG findings.<br /><br />Furthermore, the review underscores the limited predictive value of traditional laryngoscopic examinations alone and points out the role of LEMG in detecting conditions such as RLN and SLN injuries, aiding in the management of dysphonia and dysphagia. It confirms that LEMG is well-tolerated by patients and useful in complex cases including bilateral VF paralysis.<br /><br />The authors advocate for further research and standardization in LEMG practices to improve its diagnostic and prognostic capabilities, ultimately enhancing patient care for those suffering from laryngeal neuropathies.

Keywords

laryngeal electromyography

laryngeal neuropathies

recurrent laryngeal nerve

superior laryngeal nerve

vocal fold motion

laryngeal synkinesis

quantitative analysis

motor unit potential

dysphonia

dysphagia