Value of Laryngeal Electromyography in Diagnosis of Vocal Fold Immobility

Abstract

We conclude that LEMG and evoked LEMG behavior plays a crucial role in the diagnosis of vocal fold immobility. The decreased recruitment activities on LEMG and the decreased evoked LEMG signals with longer latency and lower amplitude reflect the severity of neuropathic laryngeal injury.

Pediatric Voice and Swallowing Disorders Related to Vocal Fold Immobility: the Use of Laryngeal EMG

“…Lack of motor unit recruitment 6 months after injury offers a poor prognosis [25•]. Partial denervation can present with decreased signals with decreased amplitude and increased latency [24]. However, analysis of the number of motor unit potentials can be subjective and is dependent on accurate needle placement [21].…”

“…Fibrillation potentials and positive sharp waves are reliable indicators of laryngeal nerve injuries [24]. However, there is insufficient data about the usefulness of fibrillation potentials and/or positive sharp waves in predicting recovery [31••].…”

“…The office setting has the benefit of avoidance of anesthesia, and the patient can phonate in an attempt to elicit a response. In-office monitoring can be performed with percutaneous monopolar or concentric bipolar needle electrodes or hook wires [21,24,28]. The approach is commonly transcervical through the cricothyroid membrane [23•].…”

“…In patients where a transcutaneous electrode placement is not an option (due to tracheotomy or difficult landmarks), transoral approaches can be used [22•]. The electrode placement is typically done by an otolaryngologist and the EMG results are often interpreted by a neurologist [24,29]. Targeted muscles include the thyroarytenoid, posterior cricoarytenoid, and cricothyroid [21].…”

“…Synkinesis can be identified by having the patient sniff (an abductor function) when monitoring the thyroarytenoid muscle [32]. Evoked laryngeal EMG has been described using a monopolar needle electrode percutaneously to stimulate the external branch of the superior laryngeal nerve and the RLN with recordings of the cricothyroid, thyroarytenoid, posterior cricoarytenoid, and cricothyroid muscles [24].…”