Laryngeal electromyography: a proposal for guidelines of the European Laryngological Society

Chinese Expert Consensus for Assessment of Vocal Function (2024): Guidelines of the Subspecialty Group of Voice, Society of Otorhinolaryngology Head and Neck Surgery, Chinese Medical Association; Subspecialty Group of Laryngopharyngology, Editorial Board of Chinese Journal of Otorhinolaryngology Head and Neck Surgery

The assessment of vocal function plays an important role in the diagnosis of voice disorders. With the continuous development of voice medicine in China, the evaluation, diagnosis, and treatment of voice disorders are gradually professionalized and standardized. Experts of the Subspecialty Group of Voice, Society of Otorhinolaryngology Head and Neck Surgery, Chinese Medical Association; Subspecialty Group of Laryngopharyngology, Editorial Board of Chinese Journal of Otorhinolaryngology Head and Neck Surgery reached the expert consensus through clinical research, literature search, and quality evaluation, as well as two meetings and two rounds of questionnaire voting. It includes the baseline information of patients, subjective and objective assessment of voice quality, voice-related quality of life assessment, laryngoscopy and vocal fold vibration evaluation, aerodynamic analysis, laryngeal neuromuscular electrophysiological function evaluation, and many other aspects. This is the first expert consensus on vocal function assessment in China and provides appropriate guidance recommendations to voice specialists, otolaryngologists, and primary care practitioners in China.

Neurophysiological Assessment in Children with Vocal Fold Paralysis: A Tertiary Center Experience

OBJECTIVE

The aim of this study is to report on experience acquired during the laryngeal electrophysiological assessment with Co-MEP and L-EMG in pediatric patients with acquired, congenital, and syndromic vocal fold paralysis (VFP), and correlate our findings with patients' characteristics, their comorbidities, and VFP etiology.

METHODS

Pediatric patients with suspected or previously diagnosed unilateral or bilateral VFP underwent electrophysiological records under general anesthesia; corticobulbar motor-evoked potentials (Co-MEPs) and laryngeal electromyography (L-EMG) of thyroarytenoid (TA) and posterior cricoarytenoid (PCA) muscles were recorded.

RESULTS

Statistical analysis revealed a statistically significant correlation between early gestational age at childbirth and TA muscle intensity (p = 0.002) and PCA muscle intensity (p = 0.002); tracheostomy presence and TA muscle intensity (p = 0.002) and PCA muscle intensity (p = 0.002); presence of genetic anomalies with intensity and latency for TA muscle and latency for PCA muscle (TA latency p = 0.015, TA intensity p = 0.021, PCA latency p = 0.035); congenital presentation of VFP and an increased intensity for TA muscle (p = 0.04); latency and intensity for TA muscle (p = 0.024); TA muscle intensity and PCA intensity (p = 0.005).

CONCLUSION

Intraoperative Co-MEPs and L-EMG are two complementary tools for evaluating the functional integrity of the structures involved in conveying signals from the motor cortex to TA and PCA muscles in children with vocal fold paralysis. Further studies are needed to establish their ability to predict the recovery of VF mobility, which could potentially lead to decannulation.

LEVEL OF EVIDENCE

4 Laryngoscope, 135:935-941, 2025.

Laryngeal dystonia and vocal tremor response to botulinum toxin injection

PURPOSE

The main objective of this study was to compare laryngeal dystonia (LD) and vocal tremor's (VT) response to botulinum toxin injection.

METHODS

Retrospective study including every patient with LD or VT injected with botulinum toxin guided by electromyography, from January 1, 2010, to September 30, 2022, at a tertiary hospital centre. Improvement was assessed with the VHI-10, grade of dysphonia in a visual analogue scale (VAS; 0-10), GRBAS(I) scale (0-3) and maximum phonation time (MPT).

RESULTS

A total of 77 patients were included, 44 patients with LD and 33 with VT. There were no differences between groups on pre-treatment VHI-10, grade of dysphonia in the VAS, MPT and G, R, B, A and I at diagnosis (p > 0.05). S was significantly higher in patients with LD (p < 0.001). After the first injection, both groups showed an increase in the grade of dysphonia on the VAS and a decrease in VHI-10, G, S and I (p < 0.05), with a higher variation in the VAS and S parameters in the LD group compared to VT (p < 0.05). In the 54 patients that performed two or more injections, G, S and I had a higher decrease in patients with LD when compared to patients with VT (p < 0.05).

CONCLUSION

BTX injection was successful in improving the VHI-10, grade of dysphonia on the VAS and G, S and I in the GRBAS-I scale for both DT and VT. LD seems to have a better response to BTX in comparison to VT.

Risk factors for the occurrence of arytenoid dislocation after major abdominal surgery: A retrospective study

The incidence of arytenoid dislocation in abdominal surgery is relatively high, the cause is unknown, and it has not received sufficient attention. To identify the risk factors of arytenoid dislocation after abdominal surgery, and to establish a clinical prediction model based on relevant clinicopathological characteristics. We retrospectively collected the clinical data of 50 patients with arytenoid dislocation (AD) and 200 patients without AD after abdominal surgery with general anesthetic tracheal intubation in our Hospital from January 2013 to December 2019. General information about the patients was collected. Univariate analysis of the factors was performed, and indicators that were statistically significant were included in multivariate logistic regression analyses to identify the relationship between clinicopathological characteristics and arytenoid dislocation. Meanwhile, a clinical prediction model was established. Multivariate logistic regression analyses showed that age, surgical methods, operative time and gastric tube were dependent predictive factors of AD after abdominal surgery. A clinical prediction model was constructed, and the AUC of the ROC curve was 0.88 (95%CI: 0.83-0.94). The calibration plot shows that the prediction curve was close to the ideal curve. Patients undergoing abdominal surgery with general anesthesia exhibit a significantly higher incidence of AD due to a combination of factors. Clinicopathological features can be used as an independent predictor of risk in patients with AD, and a clinical model has been developed that is a good predictor of AD.

Phenotypic Characterization of Laryngospasm: The Utility of Laryngeal Neurophysiological Studies

OBJECTIVE

To determine the existence of laryngeal neuropathy and the influence of gastroesophageal reflux in patients with episodic laryngospasm.

STUDY DESIGN

Single -center, observational study with prospective clinical collection.

STUDY SETTING

Prospective analysis of 18 Spanish patients with episodic laryngospasm in a Spanish Public Center collected by otolaryngologist. The recruitment dates were from January 2019 to December 2019.

METHODS

Data collection of 18 patients with episodic laryngospasm. Clinical characteristics, laryngeal neurophysiological studies and reflux esophageal testing were analyzed.

RESULTS

All patients have a trigger for the laryngospasms, being the most prevalent adopting the supine position (27.7%). EMG and ENG were pathological in 83.3 and 63.6 % respectively. Chronic bilateral denervation (increased amplitude and duration of potentials) with signs of reinnervation in the non-active chronic phase (large polyphasia), was the most prevalent finding. Evidence of gastroesophageal reflux either by pH meter, Gastroscopy or both was found in 38.8 % of patients.

CONCLUSIONS

Neurophysiological studies have confirmed the existence of laryngeal neuropathy in the majority of patients with laryngospasm. A substantial percentage of patients (38.8%) with laryngospasm had objective GERD and improved with PPIs. Laryngeal EMG and ENG can establish a more accurate diagnostic for episodic laryngospams and may supports treatment with neuromodulators.

Laryngeal photobiomodulation: application sites, interferences from body mass index and skin phototype

PURPOSE

Establish points on the neck, correspondent to the laryngeal topography, where to apply Low Level Light therapy (LLLT), to evaluate the incidence of light through variables such as skin phototype and body mass index (BMI).

METHODS

This is a cross-sectional, analytical, observational study, carried out with 15 vocally healthy women, between 18 and 50 years of age, who were divided into three groups, according to BMI and skin phototype. Six anatomical reference points were established to locate the larynx and its musculature, with visual monitoring by videonasolaryngoscopy, to assess light reach (present/absent) and degree of illumination (from very weak to very strong) in the larynx during the LASER application at doses of 3J, 6J and 9J. A flexible endoscope was used for visual monitoring during the LASER application, and subsequent image analysis.

RESULTS

The light reached the larynx at doses of 3J, 6J and 9J, in the anterior commissure of the vocal folds, membranous (thyroarytenoid muscle) and cartilaginous portions of the vocal fold and the cricothyroid muscle. The degree of LASER light illumination decreased in overweight and obese participants and increased in moderate brown and dark brown skin phototypes.

CONCLUSION

Data suggest that the LLLT penetrates differently according to skin phototype and BMI, being more evident in individuals with Fitzpatrick IV and V phototypes and less evident with higher BMI levels. The evidence that the LASER light reaches the larynx in specific anatomical points provides direction for the standardization of its use in voice practice.

Electromyographic Assessment of the External Laryngeal Muscles of Opera Singers During Phonation and Non-Phonation Tasks

INTRODUCTION

The surface EMG technique (sEMG) gives valuable assessment of vocal tract as well as diagnosis or outcome assessment in dysphonia. There are very few papers on the use of sEMG in vocal professionalists.

AIM

The aim of this study was to evaluate the electromyographic characteristics of selected external laryngeal and neck muscles in professional opera singers.

MATERIAL

The study material consisted of 50 subjects. Twenty-six opera professional singers and 24 healthy non-singers.

METHOD

Each person underwent otolaryngologic and phoniatric examination, laryngeal videostroboscopy, hearing testing, multiparametric acoustic voice analysis (multidimensional voice program) and sEMG of submentalis, cricothyroid and sternocleidomastoid muscles.

RESULTS

Statistical analysis of the values of the amplitudes of the submentalis and the cricothyroid muscles showed significant differences between the vocalists and the control group. Moreover, during vowel phonation and glissando, significantly greater differences in the asymmetry of sternocleidomastoid muscles amplitudes were observed in singers compared to the control group. In most subjects, the studied muscles did not show asymmetry during saliva swallowing.

CONCLUSIONS

Laryngeal muscle function should be assessed during different phonation and non-phonation tasks. Singers have different SEMG characteristics than non-singers. Knowledge of the patient's history and endoscopic studies is needed to interpret EMG recordings.

Current opinion on laryngeal electromyography

PURPOSE

This study evaluates expert opinion on laryngeal electromyography (LEMG).

METHODS

A cross-sectional design was used to conduct an online survey of LEMG experts in 2021. They were questioned about the number LEMG performed annually, type of electrodes used, sector worked in, pain during the test, placement of the needle electrodes, interpretation of electrical muscle parameters, diagnosis of neuromuscular injury, prognostic sensitivity in vocal fold paralysis (VFP), laryngeal dystonia, tremor and synkinesis and quantifying LEMG.

RESULTS

Thirty-seven professionals answered (23 Spanish and 14 from other countries), with a response rate of 21.56%. All physicians used LEMG. 91.9% had one- or two-years' experience and 56.8% performed 10-40 LEMG per year. 70.3% were otolaryngologists and 27%, neurologists. In 89.1% of cases, a team of electrodiagnostic physician and otolaryngologist performed LEMG. 91.3% of Spanish respondents worked in Public Health, 7.14% of other nationalities; 37.8% in a university department. Bipolar concentric needles electrodes were used by 45.9% and monopolar concentric by 40.5%. 57% professionals considered good patients' tolerance to the test. LEMG sensitivity was regarded as strong, median and interquartile range were 80.0 [60.0;90.0] to diagnose peripheral nerve injuries, less for other levels of lesions, and strong to evaluate prognosis, 70.0 [50.0;80.0]. Respondents believe locate the thyroarytenoid and the cricothyroid muscles with the needle, 80.0 [70.0;90.0], as opposed to 20.0 [0.00;60.0] the posterior cricoarytenoid. The interpretation of the electrical parts of the LEMG was strong, 80.0 [60.0;90.0]. LEMG identify movements disorders, 60.0 [20.0;80.0], and synkinesis, 70.0 [30.0;80.0]. The professionals prefer quantitative LEMG, 90.0 [60.0;90.0].

CONCLUSIONS

The experts surveyed consider LEMG that is well tolerated by patients. The insertional and spontaneous activity, recruitment and waveform morphology can be assessed easily. LEMG is mainly useful in the study of peripheral nerve injuries, and its value in VFP prognosis is considered strong.

Electrophysiological Changes on Laryngeal Motor Neuropathways Cause Voice Disorders for Postradiotherapy Patients with Nasopharyngeal Carcinoma

OBJECTIVE

This study explored electrophysiological changes in the laryngeal motor neuropathway and determined whether lesions in the laryngeal motor cortex (LMC) and its descending tract contribute to voice deterioration and peripheral nerve palsy in patients with nasopharyngeal carcinoma (NPC) postradiotherapy (RT).

STUDY DESIGNS

Prospective cohort study.

METHODS

Twenty-two patients with NPC at 2 to 4years post-RT (8 female and 14 male), 22 patients with NPC at 8 to 10years post-RT (8 female and 14 male), and 22 healthy individuals (9 female and 13 male) were selected to test their magnetic evoked potentials (MEP), motor nerve conduction, and voice quality using transcranial magnetic stimulation, laryngeal electromyography, and the XION DiVAS acoustic analysis software. Three groups were matched according to approximate age. Multiple comparisons were performed among the three groups.

RESULTS

The voice quality of post-RT patients with NPC deteriorated compared to that of healthy individuals. Bilateral LMC and their corticonuclear tracts to the bilateral ambiguous nuclei of post-RT patients with NPC were impaired according to multigroup comparisons of MEP amplitudes, latencies, and resting motor thresholds. The vagus and recurrent laryngeal nerves (RLN) of post-RT patients with NPC were impaired according to multigroup comparisons of the amplitude and latencies of the compound muscle action potential and latencies of f-waves.

CONCLUSIONS

The voice quality of patients with NPC deteriorated after RT. The pathogenesis of post-RT voice deterioration may involve radiation-induced injuries to the vagus, RLN, and bilateral LMC. Furthermore, radiation-induced injuries to the bilateral LMC may contribute to vagus and RLN palsies. These findings support the use of transcranial approaches to treating voice disorders and peripheral nerve palsies in post-RT patients with NPC.

TRIAL REGISTRATION

ChiCTR2100054425; Electrophysiological Study of Vocal-Fold Mobility Disorders After Radiotherapy for NPC Patients via Magnetic Evoked Potential and Their Correlation with Voice Quality Assessment; https://www.chictr.org.cn/bin/project/edit?pid=144429.

Aerodynamic Performance and Neuromuscular Control in Patients with Unilateral Vocal Fold Paralysis

Unilateral vocal fold paralysis (UVFP) causes glottal incompetence and poor vocal efficiency. The influence of laryngeal neuromuscular control on aerodynamics in UVFP remains unclear. This study investigated the relationship between laryngeal muscle activities using quantitative laryngeal electromyography (LEMG) and aerodynamics in UVFP. This prospective study recruited patients with UVFP, and the diagnosis was confirmed with videolaryngostroboscopy and LEMG. The patient received aerodynamic assessment and LEMG of the thyroarytenoid-lateral cricoarytenoid (TA-LCA) muscle complex and the cricothyroid (CT) muscle. The relationship between quantitative LEMG and aerodynamic parameters was analyzed. A total of 134 UVFP patients without concurrent CT muscle involvement were enrolled. Compared with the normal side, the peak turn frequency of the lesioned side was lower in the TA-LCA (p < 0.001) and CT (p = 0.048) muscles. Stepwise linear regression revealed that the turn ratio of TA-LCA muscles was a robust factor in the decrease in peak expiratory airflow (β = −0.34, p = 0.036), mean airflow during voicing (β = −0.28, p = 0.014), and aerodynamic power (β = −0.42, p = 0.019), and an increase in aerodynamic efficiency (β = 27.91, p = 0.012). In addition, the turn ratio of CT muscles was a potent factor in inducing an increase in aerodynamic resistance (β = 14.93, p = 0.029). UVFP without CT involvement still showed suppression of CT muscles on the lesioned side, suggesting that neurological impairment of the TA-LCA complex could cause asymmetrical compensation of CT muscles, further impeding aerodynamics. The residual function of TA-LCA muscle complexes facilitates less air leakage and power dissipation, enhancing aerodynamic efficiency. On the other hand, the symmetrical compensation of the CT muscles improves aerodynamic resistance.

Laryngeal electromyography, a useful tool in difficult cases of pediatric laryngeal mobility disorders

INTRODUCTION

Pediatric laryngeal mobility disorders constitute a challenge in terms of diagnosis and treatment, especially in small children and those complex patients with prior history of prolonged intubation or surgery. Laryngeal electromyography (L-EMG) may help to distinguish vocal fold paralysis from fixation.

MATERIAL AND METHODS

Ten children with laryngeal mobility disorders (including bilateral vocal fold immobility (BVFI) or unilateral vocal fold immobility (UVFI) with contralateral hypomobility) underwent suspension laryngoscopy and L-EMG between July 2019 and March 2021. The EMG data were acquired simultaneously in both thyroarytenoid muscles. Anesthesia was lightened until volitional activity appeared like cough, cry or spontaneous Valsalva maneuver.

RESULTS

We found secondary airway lesions in 2 patients and 3 vocal fold fixation. L-EMG recordings were pathologic in 4 patients (3 moderate and 1 severe nerve lesion). No recurrent laryngeal nerve injury was found in congenital BVFI cases. The data from both suspension laryngoscopy and L-EMG recordings influenced clinical decision-making.

CONCLUSIONS

L-EMG adds value to suspension laryngoscopy in the management of pediatric patients with laryngeal mobility disorders. Selected cases such as patients with iatrogenic BVFI, UVFI with associated contralateral hypomobility or patients with combined pathologies may obtain the greatest benefit.

Active and Passive Bioimplants for Vocal Fold Paralysis

Vocal fold paralysis is one of the diseases that particularly affect quality of life. While unilateral paralysis leads to glottis closure insufficiency and hoarseness, bilateral paralysis compromises respiration and limits the exercise tolerance. Bioimplants have been used to treat persistent paralysis for over 100 years. The spectrum ranges from autologous tissue transfer and resorbable or permanent injection materials to composite thyroplasty implants and active electrical implants for neurostimulation of the larynx. If bioimplants are used in accordance with the recommendations, the quality of life of affected patients can be significantly improved today.

Electromyography of the posterior cricoarytenoid muscles: a consensus guideline

PURPOSE

Since the introduction of transcutaneous-transcricoidal needle approaches, electromyography (EMG) of the posterior cricoarytenoid muscle (PCA) became easier to perform and teach. Among the Neurolaryngology working group of the European Laryngological Society, several centers have adopted PCA EMG as part of their routine EMG workup in vocal fold immobility collectively gathering long-term experience. The purpose is to give an update and an extension to already existing guidelines on laryngeal EMG with specific regard to PCA EMG.

METHODS

Consensus of all co-authors is based on continuous exchange of ideas and on joint laryngeal EMG workshop experiences over at least 7 years. A Delphi method of consensus development was used, i.e., the manuscript was circulated among the co-authors until full agreement was achieved.

RESULTS

Step-by-step instructions on how to perform and interpret PCA EMG are provided.

CONCLUSIONS

Further research should include the establishment of normal values for PCA and thyroarytenoid muscle (TA) EMG as well as studies on the nature of some unusual activation pattern commonly seen in chronically lesioned PCA.

Selective Electrical Surface Stimulation to Support Functional Recovery in the Early Phase After Unilateral Acute Facial Nerve or Vocal Fold Paralysis

This article addresses the potential clinical value of surface electrical stimulation in the acute phase of denervation after the onset of facial nerve or recurrent laryngeal nerve paralysis. These two nerve lesions are the most frequent head and neck nerve lesions. In this review, we will work out several similarities concerning the pathophysiology features and the clinical scenario between both nerve lesions, which allow to develop some general rules for surface electrical stimulation applicable for both nerve lesions. The focus is on electrical stimulation in the phase between denervation and reinnervation of the target muscles. The aim of electrostimulation in this phase of denervation is to bridge the time until reinnervation is complete and to maintain facial or laryngeal function. In this phase, electrostimulation has to stimulate directly the denervated muscles, i.e. muscle stimulation and not nerve stimulation. There is preliminary data that early electrostimulation might also improve the functional outcome. Because there are still caveats against the use of electrostimulation, the neurophysiology of denervated facial and laryngeal muscles in comparison to innervated muscles is explained in detail. This is necessary to understand why the negative results published in several studies that used stimulation parameters are not suitable for denervated muscle fibers. Juxtaposed are studies using parameters adapted for the stimulation of denervated facial or laryngeal muscles. These studies used standardized outcome measure and show that an effective and tolerable electrostimulation of facial and laryngeal muscles without side effects in the early phase after onset of the lesions is feasible, does not hinder nerve regeneration and might even be able to improve the functional outcome. This has now to be proven in larger controlled trials. In our view, surface electrical stimulation has an unexploited potential to enrich the early therapy concepts for patients with unilateral facial or vocal fold paralysis.

Vocal fold immobility with normal LEMG: A range of possibilities

OBJECTIVE

The objective of this paper is to study the etiology of vocal fold immobility with non-pathological LEMG.

METHODS

A retrospective study was performed on patients who presented with vocal fold immobility and underwent LEMG from 2009 to 2017. Those patients with normal LEMG findings were selected. The different causes of vocal fold impairment were studied.

RESULTS

Of the 120 patients included in this study, 15 had a normal LEMG recording. The different etiologies of vocal fold immobility were idiopathic, central nervous system damage, iatrogenic, and external compression.

CONCLUSIONS

Vocal fold immobility and vocal fold paralysis are not equal terms. Vocal fold immobility with normal LEMG has a heterogeneous group of causes. It is not correct to assume that the major cause of immobility in patients with normal LEMG is always cricoarytenoid joint fixation.

Hoarseness

Hoarseness is a common problem, typically of transient nature. When hoarseness does not resolve, or when it is associated with concerning symptoms, it is important to consider a wide differential and refer to an otolaryngologist. This article discusses the physiology of the voice and possible causes of dysphonia, and explores when it warrants further work-up by ENT. A discussion of diagnostic techniques and the myriad of tools to treat hoarseness follows. Additionally, the role of reflux in dysphonia is examined with a critical eye to aid in accurate assessment of the patient's complaint.

Vocal fold immobility with normal LEMG: A range of possibilities

OBJECTIVE

The objective of this paper is to study the etiology of vocal fold immobility with non-pathological LEMG.

METHODS

A retrospective study was performed on patients who presented with vocal fold immobility and underwent LEMG from 2009 to 2017. Those patients with normal LEMG findings were selected. The different causes of vocal fold impairment were studied.

RESULTS

Of the 120 patients included in this study, 15 had a normal LEMG recording. The different etiologies of vocal fold immobility were idiopathic, central nervous system damage, iatrogenic, and external compression.

CONCLUSIONS

Vocal fold immobility and vocal fold paralysis are not equal terms. Vocal fold immobility with normal LEMG has a heterogeneous group of causes. It is not correct to assume that the major cause of immobility in patients with normal LEMG is always cricoarytenoid joint fixation.

[Neurolaryngology]

Neurological and neurophysiological knowledge of neuromuscular diseases is combined in neurolaryngology with experience from laryngology. Laryngeal electromyography (LEMG) is the most important diagnostic and prognostic tool in neurolaryngology. It can be combined with diagnostic electrostimulation. Interest in LEMG today extends beyond the thyroarytenoid muscle to all accessible laryngeal muscles. LEMG should be performed and interpreted according to a standardized protocol. Main applications of LEMG are confirmation, topodiagnostic and prognostic assessment of vocal fold paralysis. It is possible to differentiate fresh from old recurrent laryngeal nerve lesions as well as mechanical vocal fold fixations from paralysis. Needle guidance for botulinum toxin injections in spasmodic dysphonia and for augmentation laryngoplasty can be supported by LEMG, but also by laryngeal ultrasound. The timing of therapy for temporary and permanent augmentations, thyroplasty and reinnervation surgery may be better defined with experience from neurolaryngology. The use of diagnostic neurostimulation can reveal any remaining active movement potential of a vocal fold and thus help identify candidates for future laryngeal pacemaker treatments. Other topics in neurolaryngology include spasmodic dysphonia and underlying neurological diseases such as stroke, central vocal fold paralysis, essential tremor and Parkinson's disease. Laryngoscopic, clinical and LEMG characteristics of these diseases are presented.

Anesthetic Management for Awake Tubeless Suspension Microlaryngoscopy

OBJECTIVES/HYPOTHESIS

Patients' eligibility for bilateral selective laryngeal reinnervation surgery is evaluated by suspension microlaryngoscopy (SML) examination with laryngeal electromyography (LEMG). Maintaining spontaneous ventilation, with remifentanil sedation/analgesia without endotracheal tube, to allow the patient to phonate with the surgeon during awake, LEMG is a major challenge for the anesthesiologist and the otorhinololaryngologist. The objective of this study was to evaluate the safety and efficacy of a novel anesthesia protocol to manage airway access during awake tubeless SML.

STUDY DESIGN

Retrospective study.

METHODS

Anesthesia records of patients undergoing awake SML with LEMG were retrospectively analyzed. Procedures were performed with remifentanil sedation/analgesia with targeted controlled infusion (TCI) in combination with local anesthesia. The main outcome was the failure rate of the anesthesia protocol during the procedure. Secondary outcomes were as follows: rate of apnea requiring ventilation, airway bleeding, regurgitation, hemodynamic data as well as vasopressor use, complications, and surgeon satisfaction with the procedure.

RESULTS

Data were obtained for 39 patients between November 2017 and September 2019, the mean age was 52 years and 29 (74%) were female. All procedures were completed without complications (0% [0-9]). Three patients (8% [1.6-20.8]) had an intraoperative episode of hypoxemia requiring mask reventilation. There was no airway bleeding, no regurgitation, and no hypotensive episode. Three patients (8% [1.6-20.8]) had noninvasive ventilation for respiratory distress after the end of the procedure.

CONCLUSIONS

Our results show that awake tubeless SML allowing phonation during LEMG can be realized under sedation and local anesthesia. However, further data are needed concerning the intraoperative and postoperative safety of the procedure.

LEVEL OF EVIDENCE

4. Laryngoscope, 2021.

Clinical and Electromyographic Assessment of Swallowing in Individuals with Functional Dysphonia Associated with Dysphagia Due to Muscle Tension or Atypical Swallowing

Introduction: Over the past few years, attention has been paid to the coexistence of dysphonia with dysphagia, in the context of functional disorders. The aim of this work was to objectify logopaedic examination of dysphonic patients with coexisting swallowing difficulties by surface electromyography. Methods: The material of the work included 58 patients with muscle tension dysphonia (MTD). Each patient underwent otolaryngologic, phoniatric and logopaedic examination. We collected information about medical history and asked patients to fill out Reflux Symptom Index (RSI), Eating Assessment Tool (EAT-10), Dysphagia Handicap Index (DHI) and Swallowing Disorder Scale (SDS). The algorithm of dysphagia diagnostics in our clinic assumes parallel surface electromyography (SEMG) during Functional Endoscopic Evaluation of Swallowing. Results: In comparison to patients suffering from atypical swallowing, patients with muscle tension dysphagia (MTDg) obtained higher values from almost all questionnaires. Logopaedic evaluation revealed abnormalities in the structure and efficiency of the articulatory organs and in the assessment of primary functions. Patients with more abnormalities in logopaedic examination had significantly higher infrahyoid muscle activity during swallowing observed in EMG. Patients with non-normative swallowing pattern had significantly greater asymmetry of the average and maximum amplitude of masseters, as well as submental muscles. Patients with higher percent of muscles asymmetry gained higher scores in questionnaires. Conclusions: Surface electromyography objectifies logopaedic examination of patients with swallowing difficulties. The results of this work showed that, apart from longer swallows, patients with MTDg differ from patients with non-normative swallowing patterns in the muscle activity measured by SEMG, abnormalities in logopaedic evaluation and the severity of complaints reported by patients.

Diagnostic limitation of laryngostroboscopy in comparison to laryngeal electromyography in synkinesis in unilateral vocal fold paralysis

Purpose

In clinical practice, laryngo(strobo)scopy (LS) is still mainly used for diagnostics and management of unilateral vocal fold paralysis (UFVP), although only laryngeal electromyography (LEMG) can provide information on causes of vocal fold immobility, especially on possible synkinetic reinnervation after recurrent laryngeal nerve (RLN) injury. The goal of this retrospective study was the evaluation whether signs of synkinetic reinnervation in LS can be objectified in comparison to LEMG data.

Methods

Between 1/2015 and 2/2018, 50 patients with laryngostroboscopically suspected UVFP received routine LEMG examination. The LEMG findings were retrospectively compared with LS findings. The LEMG data analysis focused on the diagnosis of synkinetic reinnervation of the TA/LCA and/or PCA. The digital LS recordings were retrospectively re-evaluated by phoniatricians considering 22 selected laryngostroboscopic parameters.

Results

LEMG revealed synkinesis in 23 (46%) and absence of synkinesis in 27 (54%) patients. None of the 22 parameters showed significant association between patients with synkinetic reinnervation and LS findings. The only laryngostroboscopic parameter that was significantly associated with a silent LEMG signal compared to single fiber activity in LEMG was a length difference on the side of the UVFP (p-value 0.0001; OR 14.5 (95% CI 3.047–66.81; Sensitivity 0.5; Specificity 0.9355).

Conclusion

Our findings show that synkinesis cannot be diagnosed using only LS. This study underlines the importance of LEMG in clinical routine for detection of laryngeal synkinesis in patients with UVFP before any further therapeutic steps are initiated to avoid later therapy failure.

Crumley's Classification of Laryngeal Synkinesis: A Comparison of Laryngoscopy and Electromyography

OBJECTIVES/HYPOTHESIS

Applying the principles of misdirected nerve regeneration to the larynx, Roger Crumley in 1989 coined the term laryngeal synkinesis (LS) which he later (2000) classified into 4 types (type I - good voice, type II - involuntary twitches and poor voice, type III - adduction during inspiration, type IV - abduction during phonation). Neurophysiological data were not available for all LS patients at that time. The current study was undertaken to utilize and test the Crumley classification for a clinical interrater comparison and, secondly, compare predicted with actual laryngeal electromyography (LEMG) results.

STUDY DESIGN

Descriptive study.

METHODS

Laryngoscopic and LEMG data of patients with unilateral vocal fold paralysis (VFP) of 6 months duration or longer were combined for retrospective evaluation. Forty-five data sets were available for laryngoscopic classification by two local laryngologists and by Roger Crumley. Twenty-three data sets with complete thyroarytenoid (TA) and posterior cricoarytenoid (PCA) - EMG data were used to compare predicted with actual LEMG results.

RESULTS

Local laryngologists were able to classify 24 of 45, Crumley 30 of 45 cases into one of the 4 synkinesis types. There was substantial agreement between examiners (Cohens Kappa 0.66 [P < .001]). Comparison of predicted and actual LEMG data showed only moderate agreement. EMG sykinesis rates were lower in TA than in PCA and highest in Crumley type I cases.

CONCLUSION

The Crumley classification is helpful in describing and understanding synkinesis. It does not always correlate predictably with actual LEMG data. A complete LEMG mapping of all intrinsic muscles may improve understanding of chronic VFP.

LEVEL OF EVIDENCE

4. Laryngoscope, 131:E1605-E1610, 2021.

Hyaluronic Acid Injection Laryngoplasty for Unilateral Vocal Fold Paralysis-A Systematic Review and Meta-Analysis

Unilateral vocal fold paralysis (UVFP) is a common disorder that may cause glottal closure insufficiency and then hoarseness of voice and aspiration during swallowing. We conducted a systematic review and meta-analysis to evaluate whether hyaluronic acid (HA) injection laryngoplasty (IL) is an effective treatment for patients with UVFP. Comprehensive systematic searches were undertaken using PubMed, EBSCO Medline, and Cochrane Library databases. We appraised the quality of studies according to preset inclusion and exclusion criteria. The lengths of follow-up were divided into “short-term” (3 months or shorter), “medium-term” (6 months), and “long-term” (12 months or longer). We performed random-effect meta-analysis to estimate the changes in voice-related quality of life, perceptual evaluation by grading systems, voice lab analysis of maximal phonation time, and normalized glottal gap area, before and after HA IL. Fourteen studies were eligible for the final analysis. The results showed that patients’ glottal closure insufficiency could be improved; maximal phonation time could be prolonged; perceptual evaluations of the voice and quality of life were better after HA IL, but the duration of treatment effect varied among different studies. In conclusion, HA IL is an effective treatment for UVFP, which may achieve a long-term effect and therefore reduce the likelihood of requiring permanent medialization thyroplasty.

PCA Atrophy and Synkinesis as the Main Factors for Persistent Vocal Fold Immobility in RLN Paralysis

OBJECTIVES/HYPOTHESIS

An immobile vocal fold due to recurrent laryngeal nerve (RLN) injury usually shows no gross signs of atrophy and lies near the midline. In 1881, Felix Semon proposed that this phenomenon was due to a selective injury of nerve fibers supplying the posterior cricoarytenoid muscle (PCA) and supported this with postmortem proof of selective PCA atrophy. In recent decades, evidence has emerged that the RLN regenerates after injury but does not always result in useful motion of the vocal folds. It has been proposed that this is caused by laryngeal synkinesis. Laryngeal synkinesis describes a random distribution of regenerated nerve fibers to opposing vocal fold muscles. This study was conducted to clarify the relative contribution of these two potential pathomechanisms in our patient population.

STUDY DESIGN

Retrospective case analysis.

METHODS

Retrospective analysis of laryngeal EMG results from cases with RLN paralysis of at least 6 months duration seen at our neurolaryngology clinic.

RESULTS

Out of 118 PCA EMGs, there was not a single normal or near-normal tracing, whilst 33.3% of TA EMGs indicated normal or near normal innervation. PCA EMGs showed signs of persistent high-grade partial denervation (41.5%) as a sign of atrophy, moderate or strong synkinesis (21.2%), or a combination of both (37.3%).

CONCLUSIONS

In chronic RLN paralysis the intrinsic laryngeal muscles are affected to different extents either by atrophy or synkinesis or a combination of both. The PCA is always affected. The lesser damage to TA innervation explains the commonly seen maintenance of vocal fold muscle bulk.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E1244-E1248, 2021.

Guidelines for the Management of Unilateral Vocal Fold Paralysis From the Korean Society of Laryngology, Phoniatrics and Logopedics

The Korean Society of Laryngology, Phoniatrics and Logopedics appointed a task force to establish clinical practice guidelines for the management of unilateral vocal fold paralysis (UVFP). These guidelines cover a comprehensive range of management-related factors, including the diagnosis and treatment of UVFP, and provide in-depth information based on current, up-to-date knowledge. Detailed evidence profiles are provided for each recommendation. The CORE databases, including OVID Medline, Embase, the Cochrane Library, and KoreaMed, were searched to identify all relevant papers, using a predefined search strategy. When insufficient evidence existed, expert opinions and Delphi questionnaires were used to fill the evidence gap. The committee developed 16 evidence-based recommendations in six categories: initial evaluation (R1–4), spontaneous recovery (R5), medical treatment (R6), surgical treatment (R7–14), voice therapy (R15), and aspiration prevention (R16). The goal of these guidelines is to assist general otolaryngologists and speech-language pathologists who are primarily responsible for treating patients with UVFP. These guidelines are also intended to facilitate understanding of the condition among other health-care providers, including primary care physicians, nurses, and policy-makers.

Facial nerve electrodiagnostics for patients with facial palsy: a clinical practice guideline

PURPOSE

Facial nerve electrodiagnostics is a well-established and important tool for decision making in patients with facial nerve diseases. Nevertheless, many otorhinolaryngologist-head and neck surgeons do not routinely use facial nerve electrodiagnostics. This may be due to a current lack of agreement on methodology, interpretation, validity, and clinical application. Electrophysiological analyses of the facial nerve and the mimic muscles can assist in diagnosis, assess the lesion severity, and aid in decision making. With acute facial palsy, it is a valuable tool for predicting recovery.

METHODS

This paper presents a guideline prepared by members of the International Head and Neck Scientific Group and of the Multidisciplinary Salivary Gland Society for use in cases of peripheral facial nerve disorders based on a systematic literature search.

RESULTS

Required equipment, practical implementation, and interpretation of the results of facial nerve electrodiagnostics are presented.

CONCLUSION

The aim of this guideline is to inform all involved parties (i.e. otorhinolaryngologist-head and neck surgeons and other medical specialists, therapeutic professionals and the affected persons) and to provide practical recommendations for the diagnostic use of facial nerve electrodiagnostics.

Prevalence and characterisation of vocal fold motion impairment (VFMI) in patients with Multiple system atrophy compared with Parkinson's disease

INTRODUCTION

Multiple system atrophy (MSA) is a neurodegenerative disorder in which vocal fold mobility can be affected, sometimes leading to life-threatening situations. Our aim was to know if laryngeal examination could help differentiate MSA from Parkinson's disease (PD).

MATERIALS AND METHODS

Between 2004 to 2014, all consecutive patients diagnosed with probable MSA were included in this retrospective, monocentric study. Flexible laryngoscopy was obtained in 51 MSA patients and compared with 27 patients with Parkinson's disease (PD). Laryngeal muscles EMG was available in 6 MSA patients.

RESULTS

Vocal fold motion impairments (VFMI) was found in 35 (68.6%) MSA patients: 15 (29.4%) had uni- or bilateral vocal fold abnormal movement (VFAM), 13 (25.5%) had uni- or bilateral vocal fold abductor paresis (VFABP), 4 (7.8%) had uni- or bilateral vocal fold adductor paresis (VFADP), 10 (19.6%) had bilateral vocal fold paralysis (BVFP). VFMI was found in 13 PD patients (48.1%) all of whom had VFADP. Presence of BVFP was found associated with stridor (P<0.001) and dysphagia (P=0.002). In all muscles examined in 6 MSA patients, the EMG showed neuropathic patterns.

CONCLUSIONS

Our data support that VFMI may be encountered in two-thirds of MSA with a variable degree of gravity. Laryngological examination should be considered as a supplementary tool for the diagnosis and prognosis of MSA. VFMI in particular VFAM, VFABD and BVFP should be discussed as an additional possible red flag even at an early stage of MSA and could help discriminate MSA from PD.

Objectivation of laryngeal electromyography (LEMG) data: turn number vs. qualitative analysis

Purpose

This paper describes a first attempt to quantify LEMG data based on turn number calculation. The results obtained for both healthy and ailing thyroarytenoid (TA) muscles of patients with unilateral vocal fold immobility (UVFI) were compared with the respective qualitative evaluation concerning volitional activity to determine whether the two types of analyses deliver similar results.

Methods

LEMG data obtained from 44 adults with UVFI were considered for the study. Semiquantitative evaluation of TA volitional activity and turn number were assessed for the ailing and the healthy TA and the difference in percentage was calculated. Paired data were compared with the Wilcoxon signed-rank test. The volitional activity assessment and the turn number evaluation were compared with the Kruskal–Wallis test, and their relationship was tested with the Kendall rank correlation.

Results

Datasets of 27 patients were considered compatible with turns/s calculation. The results showed that complete paralysis correlated with no turns; single fiber volitional activity with 62–208 turns/s, strongly decreased volitional activity with 198–501 turns/s; and dense volitional activity with 441–1234 turns/s. On the ailing VF only, the Kruskal–Wallis test showed a statistically significant difference (p = 0.0001), and the Kendall rank correlation a positive relationship (r = 0.853,p ≤ 0.0001) between the volitional activity rating and the turn number assessment.

Conclusions

Our preliminary results showed that turn number evaluation is an effective tool to confirm LEMG qualitative analysis, and that, in combination with laryngostroboscopy and voice assessment, can help improving the accuracy of the diagnosis and prognosis and the effectiveness of the chosen therapy.

Comparison between Intramuscular Multichannel Electrodes and Supramysial Multichannel Electrodes via EMG Measurements for Potential Use as Larynx Stimulation Electrodes: In Vivo Animal Analysis

One of the most common causes for larynx paralysis is the injury of the recurrent laryngeal nerve which, among others, causes the paralysis of the posterior cricoarytenoideus muscle (PCA). Electrical stimulation of PCA offers an approach to retaining the function of the paralyzed larynx muscle. The study aim was to test the applicability of an intramuscular multichannel array electrode as a measuring electrode for myoelectrical potentials and as a possible electrode for stimulation, e.g., posterior cricoarytenoideus muscle stimulation. For this purpose, two different kinds of electrodes were compared. 42 intramuscular multichannel array electrodes and 11 supramysial multichannel electrodes were implanted into the triceps brachii muscle of rats. The triceps brachii muscle of rats is suitable to serve as a substitute muscle for the human PCA muscle in an in vivo animal model. It has the same striated muscle cells, is of comparable size, and fundamentally serves a similar function to the human PCA muscle during normal respiration. Walking and breathing are circular functions that cause minimal muscle fatigue when carried out steadily. In total, the myoelectrical activity of 6703 steps could be recorded, allowing a comparison and statistical analysis of the EMG amplitudes and EMG activation patterns. Small differences can be detected between the EMG signals of both electrode types which, however, can be explained physiologically. Both electrode types reveal the basic characteristics of the triceps brachii muscle activity, namely the muscle contraction strength and the coordination pattern. This indicates that the intramuscular electrode may be applied for a detailed analysis of the human larynx.

The surgical treatment of unilateral vocal cord paralysis (UVCP): qualitative review analysis and meta-analysis study

PURPOSE

The objectives of this meta-analysis were to summarize the key surgical procedures for UVCP and to evaluate which of these is associated with better results in terms of vocal improvement.

METHODS

A systematic review of the literature was conducted in search of articles focused on the comparison of voice outcome between different techniques for the UVCP treatment. Then, a quantitative analysis was carried out for papers published from 2013 onwards, reporting only adult patients with unilateral paralysis for each study, and each surgical technique was evaluated for its capability of achieving good functional outcomes in terms of GRBAS-I scale and maximum phonation time in seconds (MPT).

RESULTS

The search identified 1853 publications. A total of 159 articles were stratified and included according to our selection criteria. 21 out of 159 articles were selected for quantitative synthesis. For trans-oral techniques: the mean GRBAS-I scale were 2.33 before injection and 0.41 after injection. The mean MPT before injection were 4.78 and 12.50 after injection. For open techniques the mean GRBAS-I scale were 2.43 before surgery and 0.68 after surgery. For open technique, the mean MPT were 3.50 before surgery and 12.40 after surgery.

CONCLUSIONS

The two types of techniques lead to an improvement in terms of vocal outcomes emphasizing that from the examined literature an indication emerges to perform an early injection because this could reduce the possible need for a more invasive intervention of permanent medialization in the future.

Inter-rater reliability of seven neurolaryngologists in laryngeal EMG signal interpretation

Purpose

Laryngeal electromyography (LEMG) has been considered as gold standard in diagnostics of vocal fold movement impairment, but is still not commonly implemented in clinical routine. Since the signal interpretation of LEMG signals (LEMGs) is often a subjective and semi-quantitative matter, the goal of this study was to evaluate the inter-rater reliability of neurolaryngologists on LEMGs of volitional muscle activity.

Methods

For this study, 52 representative LEMGs of 371 LEMG datasets were selected from a multicenter registry for a blinded evaluation by 7 experienced members of the neurolaryngology working group of the European Laryngological Society (ELS). For the measurement of the observer agreement between two raters, Cohen’s Kappa statistic was calculated. For the interpretation of agreements of diagnoses among the seven examiners, we used the Fleiss’ Kappa statistic.

Result

When focusing on the categories “no activity”, “single fiber pattern”, and “strongly decreased recruitment pattern”, the inter-rater agreement varied from Cohen’s Kappa values between 0.48 and 0.84, indicating moderate to near-perfect agreement between the rater pairs. Calculating with Fleiss’ Kappa, a value of 0.61 showed good agreement among the seven raters. For the rating categories, the Fleiss’ Kappa value ranged from 0.52 to 0.74, which also showed a good agreement.

Conclusion

A good inter-rater agreement between the participating neurolaryngologists was achieved in the interpretation of LEMGs. More instructional courses should be offered to broadly implement LEMG as a reliable diagnostic tool in evaluating vocal fold movement disorders in clinical routine and to develop future algorithms for therapy and computer-assisted examination.

Isolated Recovery of Adductor Muscle Function Following Bilateral Recurrent Laryngeal Nerve Injuries

OBJECTIVES/HYPOTHESIS

The aim of this study was to analyze the phoniatric and respiratory outcomes of a subset of bilateral vocal cord paralysis (BVCP) patients who were all treated with unilateral endoscopic arytenoid abduction lateropexy (EAAL). EAAL is a nondestructive, minimally invasive glottis widening operation, which does not damage either the surgically treated or the contralateral vocal cord. Therefore, it does not impair the regeneration potential of the recurrent laryngeal nerve.

STUDY DESIGN

Case series.

METHODS

Ten out of 21 BVCP patients who were treated with EAAL showed signs of isolated adduction recovery at 1 year and were chosen for this study. Functional results (objective and subjective voice analysis, spirometric measurement) and vocal cord movements were assessed preoperatively, 1 week and 1 year after EAAL. Laryngeal electromyography was performed on the 12th postoperative month.

RESULTS

The volitional adductor movement seen on laryngoscopy was corroborated by laryngeal electromyography evaluation. Peak inspiratory flow increased significantly after EAAL. Quality-of-life scores also showed high patient satisfaction. Shimmer showed consistent improvement along with harmonic-to-noise ratio and average maximal phonation time in parallel with the improving vocal cord movement. Complex voice analysis and subjective self-evaluation tests also demonstrated significant improvement.

CONCLUSIONS

EAAL, as a minimally invasive, nondestructive airway widening technique, does not interfere with the potential regeneration process that can still occur after BVCP, allowing for laryngeal functional recovery. It is a safe and effective treatment for BVCP that allows a simple solution with good phonatory, swallowing, and respiratory benefits by unilateral passive and reversible vocal cord lateralization.

LEVEL OF EVIDENCE

4 Laryngoscope, 129:2334-2340, 2019.

Vocal fold paresis: Medical specialists' opinions on standard diagnostics and laryngeal findings

PURPOSE

There is still no clear consensus on the diagnostic value of specific laryngeal findings in patients with suspected vocal fold paresis (VFP). The aim of the study was to establish expert opinion on criteria for the diagnosis of VFP in Europe.

METHODS

A cross-sectional survey using the questionnaire introduced by Wu and Sulica for US American experts was addressed to laryngeal experts in Germany, Austria, and Switzerland and in a second survey wave to members of the European Laryngological Society.

RESULTS

100 respondents returned survey 1 (response rate 47.2%). 26% worked at a university department. 28% regularly used laryngeal electromyography (LEMG). A pathologic test results in LEMG was considered to have the strongest positive predictive value for VFP (79 ± 23%), followed by a decreased vocal fold abduction (70 ± 29%), decreased vocal fold adduction (61 ± 34%), and atrophy of the hemilarynx (61 ± 31%). The multivariate analysis showed the predictive value of LEMG was estimated lower by respondents from non-university hospital (β = - 16.33; confidence interval (CI) = - 25.63 to - 7.02; p = 0.001) and higher in hospitals with higher frequency of VFP patients per months (β = 1.57; CI = - 0.98 to 2.16; p < 0.0001). 30 ELS members returned survey 2 (response rate, 8.4%). Their answers were not significantly different to survey 1.

CONCLUSIONS

The laryngology experts in Europe rely on LEMG for diagnosis of VFP like the US American experts, but paradoxically only a minority uses LEMG frequently. Next to LEMG, motion abnormities were considered to have the best predictive value for the diagnosis of VFP.

Hemodynamic stability during laryngeal electromyography procedures

BACKGROUND

Laryngeal electromyography (LEMG) is accepted as safe, with minimal side effects. However, patient hemodynamic stability, during these procedures, has not been reported. This study aimed to investigate the hemodynamics in patients undergoing LEMG and determine the risk factors for hemodynamic changes.

METHODS

We recruited 89 consecutive patients who underwent LEMG. Baseline and postprocedural changes in vital signs were analyzed.

RESULTS

Diastolic blood pressure (DBP) increased from 75.08 ± 11.54 mmHg preprocedure to 77.4 ± 11.91 mmHg postprocedure (p = .006); pulse rate (PR) increased from 78.1 ± 13.3 beats per minute preprocedure to 80.02 ± 13.69 postprocedure (p = .027). Systolic blood pressure (SBP) and oxygen saturation were unchanged after the procedure. However, about 17% of patients experienced profound changes in vital signs of >20% above baseline during LEMG. The hemodynamic changes did not differ between sexes or between surgical and non-surgical etiologies of vocal fold paralysis. Two patients experienced profound but reversible near-syncope during the procedure.

CONCLUSIONS

LEMG is a safe procedure with few immediate complications, though it may affect the patient's hemodynamic status by increasing DBP and PR. The hemodynamic monitoring is recommended so that timely intervention can be applied in case any warning sign occurs.

Laryngeal EMG: Preferential damage of the posterior cricoarytenoid muscle branches especially in iatrogenic recurrent laryngeal nerve lesions

OBJECTIVE

Laryngeal electromyography (LEMG) of the thyroarytenoid (TA) muscle alone may not be sufficient in all patients to characterize or prove a recurrent laryngeal nerve (RLN) lesion in cases of vocal fold immobility. LEMG of the posterior cricoarytenoid (PCA) muscle may provide additional information.

STUDY DESIGN

Retrospective review.

METHOD

Between 2008 and 2016, 339 patients in our laryngeal paralysis clinic were examined by transcutaneous needle TA-LEMG and, if tolerated, by PCA-LEMG. LEMGs were rated and compared according to criteria of the European Laryngological Society. Etiology was categorized as iatrogenic, noniatrogenic, or malignancy related.

RESULTS

A total of 282 out of 339 patients had a partial or complete RLN or vagal nerve lesion: 178 iatrogenic, 74 noniatrogenic, and 30 because of nerve involvement by malignancies. Of paralytic vocal folds, 35.7% had normal or near-normal TA innervation, whereas corresponding PCA traces (if present) were pathologic in 94.6%. Comparing pairs of TA and PCA-LEMGs in paralysis of less than 4 months duration showed a predominance of PCA branch injuries in iatrogenic lesions (71.7 %), while in noniatrogenic lesions this was less pronounced (44.4%). In the few malignancy cases, there was an almost even distribution. Synkinetic reinnervation was earlier in iatrogenic RLN lesions.

CONCLUSION

PCA-LEMG was better in proving an RLN lesion than TA-EMG alone. Our findings suggest etiology-dependent differences in the TA/PCA lesion pattern. To confirm this, larger sample sizes are needed. A preferential damage to PCA innervation in iatrogenic lesions could be relevant for further improvements of intraoperative neuromonitoring.

LEVEL OF EVIDENCE

4. Laryngoscope, 128:1152-1156, 2018.

Electromyography-guided hyaluronic acid injection laryngoplasty in early stage of unilateral vocal fold paralysis

INTRODUCTION AND OBJECTIVE

To assess the effectiveness of electromyography-guided hyaluronic acid injection laryngoplasty in the early stage of unilateral vocal fold paralysis in terms of patient recovery from dysphonia and quality of life.

METHODS

Between January and December 2014, 28 patients with unilateral vocal fold paralysis underwent electromyography and injection of hyaluronic acid in the thyroarytenoid muscle. We compared the voice handicap index, grade, roughness, breathiness, asthenia, strain scale (GRBAS), videostroboscopic parameters and maximum phonation time assessed before, 15 days and 6 months after the intervention, using the non-parametric Wilcoxon rank test.

RESULTS

Out of the 28 patients, 1 had a haematoma in the injected vocal fold (3.57%) and 6 required second injections. The maximum phonation time of the vowel /e/ increased from 6.07 to 12.14 sec. (15 days post-intervention) and subsequently 12.75 (6 months post-intervention). There was also a significant improvement in the grade, roughness, breathiness, asthenia, strain scale in parameters G, B and A both 15 days and 6 months after the intervention. The voice handicap index score decreased from 58.29 to 37.63 (15 days post-intervention) and 29.64 (6 months post-intervention).

CONCLUSIONS

Electromyography-guided hyaluronic injection laryngoplasty in unilateral vocal fold paralysis enables, in the same intervention, neuromuscular assessment and temporary treatment of glottic insufficiency with a low risk of complications and improvement in patient's quality of life. This may reduce the need for subsequent treatments, but further research is required to confirm these findings.

Laryngeal electromyographic changes in postthyroidectomy patients with normal vocal cord mobility

Thyroidectomy has been used for the treatment of thyroid disease for more than 100 years. In spite of the advancement of surgical techniques, there is still a risk of laryngeal nerve injury. The risk of partial or complete injury still depends on some surgical and disease-related factors. The aim of this study is to show the partial injury and to establish these risk factors via laryngeal electromyographic analysis (LEMG) in postthyroidectomy patients with normal vocal cord motion and mucosal anatomy. Patients who had undergone thyroid surgery were enrolled in this prospective study. LEMG analysis was performed to all patients with normal vocal cord mobility preoperatively and was repeated after the first and the third months of surgery. Thyroarytenoid (TA) and cricothyroid (CT) muscles were used to evaluate recurrent and external branch of superior laryngeal nerves, respectively. Four of the 32 patients had mild-to-moderate degrees of partial LEMG changes during preoperative LEMG analysis of TA and CT muscles on each side. After 3 months of surgery, there was a statistically significant worsening of LEMG findings in the right and left external branches of superior and left recurrent laryngeal nerves. Disease and surgery-related risk factors were analyzed. However, there was no significant relationship on the progression of LEMG findings according to these parameters. This is the first prospective study which supports the risk of progression of LEMG changes in patients with normal laryngoscopic examination after thyroid surgery. No reliable significant risk factor was found influencing the LEMG progression.

Laryngeal pacing for bilateral vocal fold paralysis: Voice and respiratory aspects

OBJECTIVE

To evaluate the effects of neurostimulation with the laryngeal pacemaker (LP) system in patients with bilateral vocal fold paralysis (BVFP) in terms of voice quality and respiratory function.

STUDY DESIGN

Feasibility study, first-in-human, single-arm, open-label, prospective, multicenter study with group-sequential design and 6-month follow-up period, as described in details in our previous publication.

METHODS

Nine symptomatic BVFP subjects were unilaterally implanted with the LP system at three study sites in Germany and Austria. Subjective and objective voice function, spirometric parameters other than peak expiratory/inspiratory flow (PEF/PIF), and PEF-meter self-assessment were evaluated pre- and 6 months postimplantation.

RESULTS

In general, the LP system did not considerably change the voice quality of the implanted patients. Only the sound pressure level range improved significantly 6 months postimplantation (P = 0.018). The LP system implantation did not affect the glottal closure configuration, the duration of the closed phase, and the mucosal wave of the implanted side. The evaluated spirometric parameters were not significantly affected by laryngeal pacing, whereas PEF meter self-assessment showed a stable and significant (P = 0.028) improvement of the PEF within a week upon activation of the LP system.

CONCLUSION

Neurostimulation with the LP system results in an immediate and stable PEF improvement, without negative effects on the voice quality. The PEF meter self-assessment confirmed the spirometry results of the PEF. The stimulated abduction did not affect the glottal closure during phonation. These results should be confirmed in larger and more homogenous patient cohorts.

LEVEL OF EVIDENCE

2b Laryngoscope, 127:1838-1844, 2017.