Laryngeal Electromyography Techniques and Clinical Use:

Safety of Laryngeal Electromyography and Repetitive Stimulation

OBJECTIVES

Laryngeal Electromyography (LEMG) is a procedure used to assess electrical signals from laryngeal muscles. It is considered to be the gold standard test for examining vocal fold paresis/paralysis. Repetitive stimulation studies, which usually are performed at the time of LEMG, can aid in assessment of neuromuscular function. Electromyography poses risks to the patient due to the use of electricity and needles. The purpose of this paper was to evaluate the safety of LEMG and discuss the possible complications.

METHODS

This was a retrospective review of patients from January 2015 through February 2022. Information from patient charts included age, sex, chief complaint, past medical history, family medical history, medications, social history, strobovideolaryngoscopy results, type of paresis, professional voice user status, presence of pacemaker, laryngeal electromyography and repetitive stimulation study results, and reported complications. Complications were considered to be anything that differed from the norm. Pain was included as a complication. Data were analyzed for relationships and significance.

RESULTS

Five hundred patients were included. Eighteen of the 500 (3.6%) experienced complications. Four (2.1%) males and 14 (4.5%) females experienced complications. Nine of the 18 (50%) reported pain after the procedure, 1 (5.56%) had excessive bleeding (controlled with pressure), 5 (27.78%) reported voice changes, and 3 (16.67%) experienced difficulty with completion of the procedure. No patients with pacemakers or patients taking anticoagulants had complications, but repetitive stimulation studies were not performed on patients with pacemakers.

CONCLUSIONS

LEMG and repetitive stimulation studies are safe and effective procedures to examine laryngeal muscles. Repetitive stimulation studies are not recommended for patients with pacemakers.

Functional outcomes after transoral CO2 laser treatment for posterior glottic stenosis: a bicentric case series

PURPOSE

The aim of this study is to evaluate functional outcomes in terms of decannulation rate and quality of life of patients affected by PGS (Grades I-IV) treated only by transoral CO₂ laser microsurgery (TOLMS) in two tertiary centers.

METHODS

An observational retrospective study was carried out, enrolling 22 patients affected by PGS who were treated by a transoral approach at two tertiary referral centers. Surgical treatment included TOLMS with tailored laser resection of the scar tissue combined with posterior cordotomy, resurfacing of the raw area with mucosal microflap, or placement of a Montgomery T-tube or Keel stent. All patients were evaluated and staged preoperatively and postoperatively, at least 6 months after the surgery. Functional outcomes were objectively evaluated by the Airway-Dysphonia-Voice-Swallowing (ADVS) staging system, Voice Handicap Index-30 (VHI-30), and Eating Assessment Tool-10 (EAT-10) questionnaires.

RESULTS

Quality of life significantly improved as measured by the VHI-30 questionnaire with a median variation of - 31.0 (p = 0.003), the EAT-10 with a median variation of - 4.0 (p = 0.042), and the ADVS with a median variation of - 3.5 (p < 0.001). No significant changes were observed in swallowing scores. We were able to decannulate 7 of 9 patients (almost 80%) with previous tracheotomy.

CONCLUSION

In conclusion, even if there is still no general agreement on an exact therapeutic algorithm to treat PGS, our results confirm that transoral surgery, in terms of scar tissue removal, combined in selected patients with posterior cordotomy and pedicled local flaps and/or placement of stents, represents a safe and effective surgical approach even for more severe PGS.

Vocal fold injection material does not preclude interpretation of laryngeal electromyography

INTRODUCTION/AIMS

Temporary vocal fold injection (VFI) is a common treatment for acute and subacute vocal fold paralysis (VFP). Laryngeal electromyography (LEMG) is useful for diagnosing neurogenic causes of VFP. This study evaluated whether the presence of VFI material prevents interpretation of LEMG in patients with acute and subacute VFP.

METHODS

Patients with acute and subacute unilateral VFP (onset ≤6 mo) who underwent temporary VFI within 3 mo preceding LEMG were evaluated. A matched control group that did not undergo VFI was also studied. The LEMG team (laryngologist and electromyographer) performed and interpreted LEMG using a pre-specified protocol, including qualitative and quantitative motor unit analysis.

RESULTS

Eighteen patients with VFI underwent LEMG successfully with interpretation of spontaneous activity and motor unit recruitment. Fourteen patients were seen in follow-up to determine accuracy of established LEMG prognosis. Seven of seven subjects with poor LEMG prognosis did not recover vocal fold motion. Five of seven subjects with fair LEMG prognosis recovered vocal fold motion. Findings were similar for the control group.

DISCUSSION

VFI augmentation material did not prevent interpretation of meaningful LEMG data in patients with acute and subacute VFP, and accurate prognoses of vocal fold motion recovery were established.

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.

Successful Use of High-Flow Nasal Cannula for Concurrent Vocal Cord Electromyography and Tubeless Microlaryngeal Surgery in a Spontaneously Breathing Adult Patient: A Case Report

Ventilation during microlaryngoscopy previously included jet ventilation, microlaryngeal endotracheal tubes, and extended apnea. Historically, apneic oxygenation provided a tubeless field but limited operative time. Increased utilization of high-flow nasal cannula in intensive care units and operating rooms has created new opportunities to expand tubeless microlaryngoscopy. Although few studies have described high-flow nasal cannula for microlaryngoscopy, there remains much to be explored. In this case report, we describe the unique setting of utilizing high-flow nasal cannula in a spontaneously breathing patient to create an optimal tubeless surgical field for both microlaryngoscopy and vocal cord electromyography.

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.

Comparison of Clinical Characteristics Between Patients With Different Causes of Vocal Cord Immobility

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.