2023 Workshop Handout Bundle-EMG Laryngeal

EMG Laryngeal

Pdf Summary

Dr. Michael C. Munin presented on the utility and techniques of laryngeal electromyography (LEMG) at the 2023 Annual Meeting of the American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM). The presentation focused on distinguishing the neurological causes of vocal fold (VF) immobility, assessing prognosis, and understanding the innervation of the larynx, particularly via the Vagus Nerve and its branches — Superior Laryngeal Nerve (SLN) and Recurrent Laryngeal Nerve (RLN).<br /><br />Laryngoscopy identifies VF immobility but fails to assess the electrophysiological state of the larynx, thereby providing no neurological diagnosis or prognosis for spontaneous recovery. LEMG, on the other hand, enables clinicians to evaluate muscle activity and nerve functionality, thus aiding in pinpointing the location and extent of lesions.<br /><br />Key anatomical insights include the roles of SLN, with its internal branch primarily sensory and the external branch controlling the cricothyroid muscle, and RLN, which innervates both adductors (e.g., vocalis, thyroarytenoid) and abductors (e.g., posterior cricoarytenoid). Injuries to these nerves can lead to hoarseness, dysphagia, and voice loss, stemming from lesions caused by factors like surgery, trauma, tumors, or neuromuscular diseases.<br /><br />LEMG techniques involve assessing the thyroarytenoid and cricothyroid muscles, noting that while minimal risks exist (e.g., gagging, minor bleeding), the procedure can be uncomfortable. The presentation detailed precise methodologies to minimize discomfort and improve accuracy.<br /><br />LEMG can also elucidate the presence of axon discontinuity and motor unit recruitment levels, providing a prognosis for recovery. Indicators such as active motor unit potentials and polyphasic potentials within six months suggest a positive prognosis, while fibrillations or positive sharp waves do not reliably predict recovery.<br /><br />A consensus statement highlighted in the presentation underscores the value of LEMG in diagnosing and treating VF paralysis. Dr. Munin concludes that LEMG is crucial for accurate diagnosis and effective management of patients with vocal fold issues.

Keywords

laryngeal electromyography

LEMG

vocal fold immobility

neurological diagnosis

Vagus Nerve

Superior Laryngeal Nerve

Recurrent Laryngeal Nerve

vocal fold paralysis

motor unit potentials

axon discontinuity