lEMG

lEMG, commonly written as LEMG, refers to laryngeal electromyography, a specialized form of EMG focused on the muscles of the larynx and vocal folds. It is used to assess the integrity of laryngeal motor pathways and to distinguish neural from muscular causes of voice and swallowing disorders.

Technique and practice often involve placing fine needle electrodes into intrinsic laryngeal muscles such as the thyroarytenoid, lateral cricoarytenoid, or cricothyroid muscles, with guidance from endoscopy or laryngoscopic visualization. In some settings, recordings may target extrinsic or supraglottic muscles. The procedure is typically performed by clinicians trained in otolaryngology or neurology and is usually conducted on an outpatient basis.

Clinical applications include evaluation of vocal fold paralysis or paresis, especially after neck or thyroid surgery, to differentiate neurogenic from myogenic etiologies, and to aid in prognosis and treatment planning. LEMG can inform decisions about interventions such as voice therapy, injection augmentation, or thyroplasty. It is also used to guide botulinum toxin injections in certain focal dystonias affecting voice, by identifying active motor units in relevant muscles.

Interpretation relies on features such as resting activity, insertional activity, motor unit potential morphology, and recruitment patterns. Neurogenic changes may show reduced recruitment and large, polyphasic potentials, while myogenic changes have distinct MUAP characteristics.

Limitations include invasiveness, potential discomfort, sampling error due to focal innervation, and the need for specialized expertise for accurate interpretation. Safety considerations include minimal risk of bleeding or infection and transient throat discomfort.