2025 Workshop Handout Bundle-W08A EMG laryngeal Munin.

W08A EMG laryngeal Munin.

Pdf Summary

This comprehensive review article by Smith and Munin (2024) discusses the utility of laryngeal electromyography (LEMG) in diagnosing and managing laryngeal neuropathies affecting the recurrent laryngeal nerve (RLN) and superior laryngeal nerve (SLN). These nerves innervate intrinsic laryngeal muscles responsible for vocal fold (VF) motion and elongation, critical for voice, swallowing, and breathing. Neuropathies, often due to iatrogenic injuries during surgeries (thyroidectomy, carotid endarterectomy, etc.), produce VF paralysis or paresis, leading to dysphonia and diminished quality of life.<br /><br />LEMG, ideally performed by a team of an electromyographer and otolaryngologist, is a powerful diagnostic tool that characterizes the extent of neuropathic injury and predicts prognosis for VF motion recovery. The review highlights advances in technique including qualitative assessments (spontaneous activity, motor unit recruitment), quantitative turns analysis (measuring motor unit recruitment, with normal ≥400 turns/s), and detection of laryngeal synkinesis—misdirected reinnervation causing simultaneous activation of adductor and abductor muscles—an important negative prognostic indicator that cannot be diagnosed by laryngoscopy alone.<br /><br />The review emphasizes that LEMG performed 2–6 weeks after onset is most predictive, with active motor unit potentials and polyphasic potentials associated with better outcomes. Incorporating synkinesis testing improves prognostic accuracy to over 90%. LEMG also informs treatment decisions: patients with poor prognosis may benefit from earlier temporary or permanent VF medialization or laryngeal reinnervation surgery rather than prolonged observation. LEMG can differentiate neuropathic from mechanical VF immobility, detect SLN lesions that affect pitch control, guide botulinum toxin injections, and influence management in bilateral VF paralysis.<br /><br />Limitations include lack of standardized nerve conduction studies for the RLN/SLN and technical challenges in electrode placement, though patient tolerance is generally good. Emerging adjunctive tools like laryngeal ultrasonography are noted. The calcium channel blocker nimodipine shows promise as a pharmacologic treatment to enhance nerve regeneration after RLN injury.<br /><br />In conclusion, LEMG provides unique pathophysiological and prognostic insights beyond laryngoscopy alone, enabling personalized, timely treatment to improve voice, swallowing, and airway outcomes after laryngeal nerve injury. It is best utilized in a multidisciplinary setting with combined qualitative, quantitative, and synkinetic analyses.

Keywords

laryngeal electromyography

LEMG

recurrent laryngeal nerve

superior laryngeal nerve

vocal fold paralysis

laryngeal neuropathies

synkinesis

motor unit recruitment

voice rehabilitation

laryngeal reinnervation surgery