• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.13 no.2
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• pp.188-192
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• 2002

Unilateral vocal cord palsy which is associated with laryngeal trauma is not uncommon event. In a 42-year-old male, a cricoid cartilage fracure had been developed after blunt trauma. The endoscopic findings showed contusion and diffuse swelling around the left arytenoid and false cord. During phonation, the mobility of left side true vocal cord was decreased. There were no level difference and displacement of the left side arytenoid. We used the laryngeal electromyography (LEMG) to make a differential diagnosis between the cricoarytenoid joint dislocation and the injury of recurrent laryngeal nerve. At the right thyroarytenoid muscle and cricothyroid muscle, the findings of LEMG were normal. But the amplitude and frequency during phonation were decreased (partial denervation) at the left thyroarytenoid muscle. LEMG is a very useful method to predict the diagnosis of vocal cord palsy.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.10 no.1
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• pp.30-36
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• 1999

Background and Objectives : Laryngeal Evoked Electromyography(EEMG) is a objective, quantitative technique to determine innervation status of larynx. The possible applications of this technique are to confirm the etiology of impaired vocal fold motion and monitor perioperative vagus nerve trauma. The purpose of this study is to develop a novel method for determining the amount of reinnervation of recurrent laryngeal nerve with accurate, inexpensive, and minimally invasive technique in human. Materials and Methods : Laryngeal EEMG was performed for 16 adults with intact vocal folds motion and 2 patients diagnosed as unilateral vocal fold paralysis. for the purpose of searching what is the optimal and noninvasive technique for laryngeal EEMG, we used 2 types of stimulation configurations(transcutaneous vs percutaneous) and 2 types of recording configurations(intramuscular vs. surface). Results and Conclusions : Percutaneous needle stimulation and surface recording of laryngeal EEMG was reliable and comparable to standard needle stimulation and invasive intramuscular needle recording. But the laryngeal EEMG by the surface recording and transcutaneous surface stimulation was not reliable and repeatable. Therefore we recommended that laryngeal EEMG by surface recording and percutaneous needle stimulation would be minimally invasive, reliable technique to know the status of reinnervation in e patients with vocal fold paralysis.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.19 no.2
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• pp.107-112
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• 2008

Diagnostic laryngeal electromyography (LEMG) relatively evaluates the electrophysiologic status of the larynx and provides critical clinical informations that no other tests can provide. However, LEMG is still not widely applied as a routine tool in clinical practice. One reason for this is the technical and interpretative difficulties of LEMG. But if LEMG is performed by a team approach consisting of an otolaryngologist and a neurologist, the technique and the interpretation of LEMG are not difficult to master. Another reason is that there is still not exact standard guideline for clinical application of LEMG. LEMG is an essential diagnostic test in evaluating patients with neuromuscular disorders, particulary vocal fold immobility, reduced mobility of vocal fold. The more we have used LEMG, the more we have found it useful in the evaluation and treatment of voice disorders, and the role of LEMG will be extended.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.30 no.1
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• pp.28-33
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• 2019

Background and Objectives : Laryngeal electromyography (LEMG) is valuable to evaluate the innervation status of the laryngeal muscles and the prognosis of vocal fold paralysis (VFP). However, there is a lack of agreement on quantitative interpretation of LEMG. The aim of this study is to measure the motor unit action potentials (MUAP) quantitatively in order to find cut-off values of amplitude, duration, phase for unilateral vocal fold paralysis patients. Materials and Method : Retrospective chart review was performed for the unilateral VFP patients who underwent LEMG from March 2016 to May 2018. Patient's demography, cause of VFP, vocal cord mobility, and LEMG finding were analyzed. The difference between normal and paralyzed vocal folds and cut-off values of duration, amplitude, and phase in MUAP were evaluated. Results : Thirty-six patients were enrolled in this study. Paralyzed vocal fold had significantly longer duration (p=0.021), lower amplitude (p=0.000), and smaller phase (p=0.012) than the normal. The cut-off values of duration, amplitude, and phase in MUAP for unilateral VFP were 5.15 ms, $68.35{\mu}V$, and 1.85 respectively. Conclusion : An analysis of MUAP successfully provided quantitative differences between normal and paralyzed vocal folds. But, additional research is needed to get more available cut-off value which is helpful to evaluate the status of laryngeal innervations.

• Annals of Rehabilitation Medicine
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• v.41 no.6
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• pp.1019-1027
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• 2017

Objective To analyze the clinical characteristics between neurogenic and non-neurogenic cause of vocal cord immobility (VCI). Methods The researchers retrospectively reviewed clinical data of patients who underwent laryngeal electromyography (LEMG). LEMG was performed in the bilateral cricothyroid and thyroarytenoid muscles. A total of 137 patients were enrolled from 2011 to 2016, and they were assigned to either the neurogenic or non-neurogenic VCI group, according to the LEMG results. The clinical characteristics were compared between the two groups and a subgroup analysis was done in the neurogenic group. Results Among the 137 subjects, 94 patients had nerve injury. There were no differences between the neurogenic and non-neurogenic group in terms of demographic data, underlying disease except cancer, and premorbid events. In general characteristics, cancer was significantly higher in the neurogenic group than non-neurogenic group (p=0.001). In the clinical findings, the impaired high pitched 'e' sound and aspiration symptoms were significantly higher in neurogenic group (p=0.039 for impaired high pitched 'e' sound; p=0.021 for aspiration symptoms), and sore throat was more common in the non-neurogenic group (p=0.014). In the subgroup analysis of neurogenic group, hoarseness was more common in recurrent laryngeal neuropathy group than superior laryngeal neuropathy group (p=0.018). Conclusion In patients with suspected vocal cord palsy, impaired high pitched 'e' sound and aspiration symptoms were more common in group with neurogenic cause of VCI. Hoarseness was more frequent in subjects with recurrent laryngeal neuropathy. Thorough clinical evaluation and LEMG are important to differentiate underlying cause of VCI.

• Journal of radiological science and technology
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• v.41 no.5
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• pp.505-509
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• 2018

VCP (Vocal Cord Paralysis) is rare but one of most serious complications related to endotracheal intubation. This report is a clinical experience of radiography and laryngeal EMG (Electromyography) assessment for the VCP. A 50-year-old woman with hoarseness, which was occurred after urethral diverticulum excision was examined by laryngoscopy. As a result of laryngoscopy, VCP was observed in left side of her vocal cord, and then recurrent laryngeal nerve damage was detected with additional CT (Computed tomography) scan and laryngeal EMG. After that, the vocal cord movement was recovered as normal state with regular conservative treatment for the 6 months.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.17 no.1
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• pp.5-13
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• 2006

• Proceedings of the KSLP Conference
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• 2014.03a
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• pp.25-25
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• 2014

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.22 no.2
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• pp.126-132
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• 2011

Background and Objectives : Vocal fold paresis is a clinical condition and considered as a continuum of neurologic dysfunction encompassing partial denervation and variable degrees and patterns of reinnervation. Its incidence, clinical presentation, significance are incompletely understood and still debated. This study describes the clinical, electromyographic findings in patients who presented with complaints of dysphonia and whose laryngoscopic finding revealed vocal fold paresis. Materials and Method : 47 patients (male : 25, female : 22) who referred to Ewha Womans University Medical Center Voice clinic for evaluation of vocal complaints were enrolled in this study. All patients had undergone a through history and physical examination including strobovideoscopic and laryngoscopic examination. Patients with in the history and/or laryngoscopic examination suggestive of vocal fold paresis were evaluated by laryngeal electromyography (LEMG). Results : Of these patients, 23 (48.9%) were found to have evidence of neuropathy on LEMG. There was no significant difference in voice symptoms and laryngoscopic findings between two groups of patients with evidence of neuropathy and who show normal findings on LEMG. Conclusion : LEMG can clinically help to guide the evaluation and management of vocal fold paresis. Due to some limitations of LEMG, laryngoscopic findings and clinical correlations should also be considered when diagnosing the vocal fold paresis.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.11 no.2
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• pp.178-184
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• 2000

Laryngeal evoked EMG is the objective and quantitative method to measure the innervation of laryngeal muscle. If there is a mobility disorder of vocal cords, the cause and location of neural lesion co be understood by the laryngeal evoked EMG and if there is a vocal cord paralysis, the degree of recovery and the policy of treatment can be determined by it. Recently, the studies of reinnervation after recurrent laryngeal nerve injury have been actively carried out. Laryngeal evoked EMC is useful to these studies. The aim of study is to know whether noninvasive methods for stimulating the recurrent laryngeal nerve and for recording of compound action potential(CAP) using surface electrode are as useful as the invasive method using needle electrode. We obtained EMG of laryngeal muscle by various stimulating and recording methods : 1) Direct nerve stimulation by placing nerve cuff electrode made out of silastic tube and platinum wire and recording by insertion of hook wire electrode into posterior cricoarytenoid(PCA) and thyroarytenoid(TA) muscles, respectively. 2) Recording of compound action potential by surface electrode after stimulation of recurrent laryngeal nerve by the insertion of 27 gauge of needle electrode. 3) Recording of compound action potential by surface electrode after stimulating the recurrent laryngeal nerve by transcutaneous blunt rod electrode at tracheoesophageal groove. The amplitude, duration and latency of the CAP evoked by recurrent laryngeal nerve stimulation were compared among the three groups. The amplitude of CAP was smallest in the group recorded from posterior cricoarytenoid and hyroarytenoid muscle, and that recorded by surface electrode after stimulation by needle electrode was largest. The difference in amplitude between the group by hook wire recording and the two groups by surface electrode recording was significant statistically. There is no significant difference in duration and latency among three groups. Since the waveform of CAP from all three methods has similar duration, latency, we concluded that noninvasive method is a useful as invasive methods.