Protocol for Neurophysiological Studies of the Superior and Recurrent Laryngeal Nerves and of the Cricothyroid and Thyroarytenoid Muscles. Clinical Utility

Neurophysiological studies of the larynx using laryngeal electroneuromyography (LENMG), which includes electromyography (EMG) and electroneurography (ENG), are essential for assessing neuromuscular function and for differential diagnosis of voice alterations (dysphonia) secondary to specific laryngeal disease or to other more general processes affecting the larynx. Laryngeal disease can be caused by lesions to nerves (superior or recurrent laryngeal nerves), lesions to muscles innervated by those nerves, abnormalities in neuromuscular transmission, central nervous system alterations, or alterations in joints. Laryngeal electromyography (LEMG) was introduced by Weddell G et al. [1]. LEMG was first used in the clinical setting by Faaborg-Andersen K, Buchthal F [2-5]. These authors studied motor unit action potentials, [6-11]. Sawashima M et al. [7] and Sram F. and Kaldova E. [12] were the first authors to report normal electromyographic findings in cricoarytenoid joint ankylosis. Faaborg-Andersen [4] was the first researcher to describe and use this technique for diagnosing paralysis secondary to surgical nerve lesions; this observation was followed by those of others [3,5,7,12-23].