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

Foerster, Gerhard; Mueller, Andréas

doi:10.1002/lary.26862

Cited by 13 publications

(15 citation statements)

References 23 publications

(51 reference statements)

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“…Higher vulnerability of abductor nerve fibers was not something we saw in acute noniatrogenic or tumorrelated cases. 15 But both findings could be explained by a lower regeneration propensity of PCA nerve fibers, which was proven in animal studies and could apply to humans as well. 17,24 In recent years laryngeal synkinesis was advocated as the main reason for a persistent vocal fold immobility or vocal fold "paralysis."…”

Section: Discussionmentioning

confidence: 95%

“…7,[12][13][14] Third, in fresh RLN lesions the damage to TA innervation is sometimes very low. 15,16 Limited impairment of TA innervation at the time of the initial lesion can explain the lower rate of aberrant synkinetic reinnervation to the TA but it cannot explain persisting focal fold immobility.…”

Section: Introductionmentioning

confidence: 99%

“…Other findings implicating the PCA's important role in persistent vocal fold immobility include a lower propensity of the PCA to reinnervate 17 and preferential damage to PCA innervation in fresh RLN lesions, especially if iatrogenic. 15 With respect to the seemingly contradictory hypotheses of selective abductor paralysis versus synkinesis we wanted to analyze LEMG data from patients with persistent vocal fold immobility longer than 6 months to search for further evidence of the role and nature of PCA damage in chronic vocal fold paralysis.…”

Section: Introductionmentioning

confidence: 99%

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

Foerster

Mueller

2020

The Laryngoscope

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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.

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Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Foerster

Mueller

2020

The Laryngoscope

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“…For example, the detection of laryngeal synkinesis is of importance for alternative therapy concepts like botulinum toxin infection, electric laryngeal stimulation or laryngeal pacing [39]. Botulinum toxin might weaken the M. thyroarytaenoideus in episodic dyspnoea attacks.…”

Section: Discussionmentioning

confidence: 99%

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

Leonhard

Volk

et al. 2019

Eur Arch Otorhinolaryngol

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PurposeLaryngeal 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.MethodsFor 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.ResultWhen 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.ConclusionA 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.

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“…Monitoring EMG signals can be used for assessment of neuromuscular transmission and muscle biomechanics 1 . EMG recording also plays an important role in characterizing the quality and magnitude of muscle reinnervation following nerve injury 2,3,4,5 . However, multiple EMG recordings over the entire period of reinnervation cannot be achieved by an invasive approach.…”

Section: Introductionmentioning

confidence: 99%

An Implantable System For Chronic In Vivo Electromyography

Zealear

Huang

2020

JoVE

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Electromyography (EMG) measures the muscle response to electrical stimulation or spontaneous activity of motor units and plays an important role in assessing neuromuscular function. Chronic recording of EMG activity reflecting a muscle's reinnervation status after nerve injury has been limited, due to the invasive nature of traditional EMG recording techniques. In this regard, an implantable system is designed for longterm, in vivo EMG recording and nerve stimulation. It has been applied and tested in a study on reinnervation of laryngeal muscles. This system consists of 1) two bipolar electrode nerve cuffs and leads for stimulating each of two nerves: the recurrent laryngeal nerve (RLN) and internal branch of the superior laryngeal nerve (SLN); 2) two EMG recording electrodes and leads for each of the two laryngeal muscles: posterior cricoarytenoid (PCA) muscle and thyroarytenoid-lateral cricoarytenoid (TA-LCA) muscle complex; and 3) a skin receptacle interfacing all implanted lead terminals to an external recording preamplifier and stimulator using a connection cable. The wire leads are Teflon-coated, multifilament, type 316 stainless steel. They are coiled and can stretch during body movement of the awake animal to prevent lead breakage and electrode migration. This system is implanted during an aseptic surgery. Afterwards, baseline EMG recordings are performed before the RLN is transected in the second surgery to study muscle reinnervation. Throughout the study, multiple physiological sessions are conducted in the anesthetized animal to obtain evoked and spontaneous EMG activity that reflects the reinnervation status of laryngeal muscles. The system is compact, free of infection over the course of the study, and highly durable. This implantable system can provide a reliable platform for research in which long-term recording or nerve stimulation is required in an anesthetized or freely moving animal.

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

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

Cited by 13 publications

References 23 publications

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

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

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

An Implantable System For Chronic In Vivo Electromyography

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