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

A comparative analysis of laryngeal nerve damage in patients with idiopathic vocal cord paralysis exhibiting different paralytic sides

Objective

To assess the extent of recurrent laryngeal nerve (RLN) and superior laryngeal nerve (SLN) damage in patients with idiopathic vocal cord paralysis (IVCP) exhibiting different paralytic sides.

Methods

A total of 84 IVCP cases were evaluated using stroboscopic laryngoscopy, voice analysis, and laryngeal electromyography (LEMG). The results were compared between patients with left-sided paralysis and right-sided paralysis based on different disease courses (less than or more than 3 months).

Results

Initially, the average age and disease progression of IVCP patients were found to be similar regardless of the side of paralysis (p > .05). Additionally, there were no significant variations in voice indicators, such as MPT, DSI, and VHI, between IVCP patients with left and right vocal cord paralysis (p > .05). Furthermore, no disparities were detected in the latencies and amplitudes of the paralyzed RLN and SLN, as well as the durations and amplitudes of the action potentials in the paralyzed TM and PCM, among IVCP patients with left and right vocal cord paralysis (p > .05). Notably, the amplitudes of the left paralytic CM were significantly lower than those of the right paralytic CM (0.45 vs. 0.53, Z = -2.013, p = .044). In addition, no disparities were observed in APDs and amplitudes between the ipsilateral PCM and TM, either for patients with left or right vocal fold paralysis (p > .05). Finally, all the IVCP patients were subdivided into two subgroups according to different disease course (less than or more than 3 months), and in each subgroup, the comparison of voice indicators and LEMG results in IVCP patients with left or right vocal fold paralysis were similar with the above findings (p > .05).

Conclusion

Overall, the degree of RLN and SLN damage appeared to be similar in IVCP patients with left and right vocal cord paralysis, provided that the disease course was comparable.

Level of Evidence

4.

An Endoscopic Cap Electrode for Posterior Cricoarythenoid Muscle Stimulation in a Porcine Model

OBJECTIVE

Laryngeal pacing (LP) is a highly anticipated therapeutic option for patients suffering from bilateral vocal fold paralysis with synkinesis. Identification of candidate patients requires confirmation of a stimulable posterior cricoidarythenoid muscle (PCA) by neuromuscular electrical stimulation (NMES). A silicone endoscopic cap electrode (ECE50) was designed to be operated as an endoscopic extension tip for selective PCA stimulation and confirmation of a glottic opening movement in a setting comparable to a gastroscopy procedure.

METHODS

A porcine animal model (n = 6) was applied to develop and test endoscopic cap prototypes in general anesthesia and sedation at a biomedical research center. Two ENT endoscopy experts evaluated and refined the cap design and performance in regard to procedure safety, endoscope handling, accessibility of the PCA by the transoral approach and selective muscle stimulation.

RESULTS

Vocal fold opening movements could be evoked by the investigators in 9 of 12 PCA muscles to stimulate with similar electric parameters. The endoscopic approach using the ECE50 proved to be atraumatic and sufficiently controlled under sedation to locate the required hotspot for NMES of the PCA.

CONCLUSION

The functionality of the novel endoscopic cap concept has been proven in a porcine model. It can be expected to be transferable to human application and to be of diagnostic importance in the screening and identification of LP candidate patients in future.

LEVEL OF EVIDENCE

NA Laryngoscope, 133:2279-2284, 2023.

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.

Functional results of endoscopic arytenoid abduction lateropexy for bilateral vocal fold palsy

Purpose

Endoscopic arytenoid abduction lateropexy (EAAL) is a reliable surgical solution for the minimally invasive treatment of bilateral vocal fold palsy (BVFP), providing a stable airway by the lateralization of the arytenoid cartilages with a simple suture. The nondestructive manner of the intervention theoretically leads to higher regeneration potential, thus better voice quality. The study aimed to investigate the respiratory and phonatory outcomes of this treatment concept.

Methods

61 BVFP patients with significant dyspnea associated with thyroid/parathyroid surgery were treated by unilateral EAAL. Jitter, Shimmer, Harmonics to Noise Ratio, Maximum Phonation Time, Fundamental frequency, Voice Handicap Index, Dysphonia Severity Index, Friedrich’s Dysphonia Index, Global-Roughness-Breathiness scale, Quality of Life, and Peak Inspiratory Flow were evaluated 18 months after EAAL.

Results

All patients had a stable and adequate airway during the follow-up. Ten patients (16.4%) experienced complete bilateral motion recovery with objective acoustic parameters in the physiological ranges. Most functional results of the 13 patients (21.3%) with unilateral recovery also reached the normal values. Fifteen patients (24.6%) had unilateral adduction recovery only, with slightly impaired voice quality. Eleven patients (18.0%) had false vocal fold phonation with socially acceptable voice. In 12 patients (19.7%) no significant motion recovery was detected on the glottic level.

Conclusion

EAAL does not interfere with the potential regeneration process and meets the most important phoniatric requirements while guaranteeing the reversibility of the procedure—therefore serving patients with transient palsy. Further, a socially acceptable voice quality and an adequate airway are ensured even in cases of permanent bilateral vocal fold paralysis.