Effects of asymmetric superior laryngeal nerve stimulation on glottic posture, acoustics, vibration

Chhetri, Dinesh K.; Neubauer, Juergen; Bergeron, Jennifer L.; Sofer, Elazar; Peng, Kevin A.; Jamal, Nausheen

doi:10.1002/lary.24209

Cited by 38 publications

(65 citation statements)

References 24 publications

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“…As mentioned before, the threshold and maximal activation levels for each nerve was rechecked at the end of the stimulation run and remained unchanged. These findings are also consistent with the laryngeal behavior in previous reports (Chhetri et al, 2012(Chhetri et al, , 2013 where the number of concurrently and independently activated muscles was smaller.…”

Section: Data Presentation and Interpretationsupporting

confidence: 92%

“…In addition, separately controlling the two laryngeal adductors appears critical to achieving the high F0 values and register jumps. The F0 range achieved in this study by separately activating the TA and LCA/IA nerve branches was at least twice that we and others have previously encountered in an in vivo canine model of phonation where all adductors were activated together by stimulating the RLN (Chhetri et al, 2012(Chhetri et al, , 2013. This would support the notion that separate control of membranous and cartilaginous glottis could significantly increase the variety of phonation types (Herbst et al, 2011).…”

Section: Discussionsupporting

confidence: 81%

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Influence and interactions of laryngeal adductors and cricothyroid muscles on fundamental frequency and glottal posture control

Chhetri¹,

Neubauer²,

Sofer³

et al. 2014

The Journal of the Acoustical Society of America

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The interactions of the intrinsic laryngeal muscles (ILMs) in controlling fundamental frequency (F0) and glottal posture remain unclear. In an in vivo canine model, three sets of intrinsic laryngeal muscles-the thyroarytenoid (TA), cricothyroid (CT), and lateral cricoarytenoid plus interarytenoid (LCA/IA) muscle complex-were independently and accurately stimulated in a graded manner using distal laryngeal nerve stimulation. Graded neuromuscular stimulation was used to independently activate these paired intrinsic laryngeal muscles over a range from threshold to maximal activation, to produce 320 distinct laryngeal phonatory postures. At phonation onset these activation conditions were evaluated in terms of their vocal fold strain, glottal width at the vocal processes, fundamental frequency (F0), subglottic pressure, and airflow. F0 ranged from 69 to 772 Hz and clustered into chest-like and falsetto-like groups. CT activation was always required to raise F0, but could also lower F0 at low TA and LCA/IA activation levels. Increasing TA activation first increased then decreased F0 in all CT and LCA/IA activation conditions. Increasing TA activation also facilitated production of high F0 at a lower onset pressure. Independent control of membranous (TA) and cartilaginous (LCA/IA) glottal closure enabled multiple pathways for F0 control via changes in glottal posture.

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Section: Data Presentation and Interpretationsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 81%

Influence and interactions of laryngeal adductors and cricothyroid muscles on fundamental frequency and glottal posture control

Chhetri¹,

Neubauer²,

Sofer³

et al. 2014

The Journal of the Acoustical Society of America

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“…It is important to quantify the affect of using a suture to adduct the folds because it has been shown that different excitation levels of laryngeal muscle excitation (i.e. different magnitudes of pre-stress) can change the dynamics and the acoustic characteristics of the folds (Chhetri et al [33]). The current study also did not account for the viscoelastic response of the vocal fold tissue, and the resultant measures of the Young's modulus of the tissue may be overestimated.…”

Section: Discussionmentioning

confidence: 99%

Characterization of the Vocal Fold Vertical Stiffness in a Canine Model

et al. 2014

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Objectives/Hypothesis Characterizing the vertical stiffness gradient that exists between the superior and inferior aspects of the medial surface of the vocal fold. Characterization of this stiffness gradient could elucidate the mechanism behind the divergent glottal shape observed during closing. Study Design Basic science. Methods Indentation testing of the folds was done in a canine model. Stress-strain curves are generated using a customized load-cell and the differential Young's modulus is calculated as a function of strain. Results Results from 11 larynges show that stress increases as a function of strain more rapidly in the inferior aspect of the fold. The calculations for local Young's modulus show that at high strain values a stiffness gradient is formed between the superior and inferior aspects of the fold. Conclusions For small strain values, which are observed at low subglottal pressures, the stiffness of the tissue is similar in both the superior and inferior aspects of the vocal fold. Consequently, the lateral force that is applied by the glottal flow at both aspects results in almost identical displacements, yielding no divergence angle. Conversely, at higher strain values, which are measured in high subglottal pressure, the inferior aspect of the vocal fold is much stiffer than the superior edge; thus any lateral force that is applied at both aspects will result in a much greater displacement of the superior edge, yielding a large divergence angle. The increased stiffness observed at the inferior edge could be due to the proximity of the conus elasticus.

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“…The larynx was exposed and exteriorized in the neck as previously described. 4,5 Briefly, a vertical midline skin incision was made to provide wide exposure of the laryngotracheal framework. Tracheostomy tube was placed and the oral endotracheal tube was removed.…”

Section: Methodsmentioning

confidence: 99%

“…4,5 The thyroarytenoid (TA) forms the physical bulk of the glottis and upon contraction causes shortening, medial bulging, and adduction of the membranous vocal folds and imparts stiffness to the body layer. The lateral cricoarytenoid (LCA) muscle adducts the vocal fold at its attachment to the vocal process, achieving posterior glottal closure.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Evaluation of the In Vivo Vocal Fold Medial Surface Shape

2017

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Summary Objectives/Hypothesis Glottal insufficiency is a common clinical problem in otolaryngology and medialization laryngoplasty (ML) procedures remain the primary treatment modality. Although the goal of ML is to restore physiologic glottal posture and achieve optimal phonation, this posture has not been directly measured. In this study, we assessed glottal medial surface contour changes with selective activation of the intrinsic laryngeal muscles (ILMs). Study Design Basic science study using an in vivo canine hemilarynx model. Methods In an in vivo canine hemilarynx, India ink was used to mark fleshpoints in a grid-like fashion along the medial surface of the vocal fold and ILMs were activated in a graded manner. A right-angled prism provided two views of the medial surface, which were recorded using a high-speed camera and used to reconstruct the 3D posture deformations of the medial surface. Results Thyroarytenoid (TA) muscle activation results in initial inferomedial bulging and increased glottal channel thickness and then glottal adduction with a final rectangular glottal channel shape. Lateral cricoarytenoid (LCA) activation closes the posterior glottis but final posture remains slightly convergent. Together, TA + LCA forms a rectangular glottis with an increased glottal vertical thickness. Posterior cricoarytenoid activation results in abduction and a slightly divergent glottis, whereas cricothyroid activation elongates the glottis and reduces the glottal channel vertical thickness. Conclusions A quantitative analysis of in vivo canine vocal fold medial surface upon activation of selective ILMs is provided. This may guide our therapeutic efforts during medialization laryngoplasty, as well as computational modeling of laryngeal physiology.

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Effects of asymmetric superior laryngeal nerve stimulation on glottic posture, acoustics, vibration

Cited by 38 publications

References 24 publications

Influence and interactions of laryngeal adductors and cricothyroid muscles on fundamental frequency and glottal posture control

Influence and interactions of laryngeal adductors and cricothyroid muscles on fundamental frequency and glottal posture control

Characterization of the Vocal Fold Vertical Stiffness in a Canine Model

Quantitative Evaluation of the In Vivo Vocal Fold Medial Surface Shape

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