Kohei Nishimoto

The impact of nimodipine administration combined with nerve-muscle pedicle implantation on long-term denervated rat thyroarytenoid muscle†

To evaluate the impact of nimodipineon reinnervation of the long‐term denervated rat thyroarytenoid (TA) muscle following nerve‐muscle pedicle flap (NMP) implantation.

Nimodipine accelerates reinnervation of denervated rat thyroarytenoid muscle following nerve-muscle pedicle implantation.

To determine whether nimodipine, an L‐type voltage‐operated calcium channel antagonist that is an accelerator of axonal regeneration following peripheral nerve injury, can expedite reinnervation of denervated rat thyroarytenoid (TA) muscle following nerve‐muscle pedicle (NMP) flap implantation.

Glottal configuration in unilaterally paralyzed larynx and vocal function

Abstract Conclusions: Three different types of glottal configuration in unilaterally paralyzed larynx were proposed by utilizing three-dimensional computed tomographic (3DCT) images. This new classification might facilitate understanding of the behavior of the affected vocal fold in terms of vocal function. Objectives: To develop a classification of glottal configuration in unilateral vocal fold paralysis (UVFP) based on the thickness and location of the vocal folds utilizing 3DCT and to compare each type of configuration with vocal function. Methods: Thirty-seven consecutive patients with UVFP underwent CT during phonation and inhalation. 3D endoscopic and coronal images on two occasions were produced. Maximum phonation time and mean airflow rate were also measured. Results: Three types of glottal configuration were proposed. The thickness of the affected vocal fold during phonation was equal to or slightly thinner than the healthy fold in 10 patients (type A). The affected fold of the remaining 27 was thin during phonation; they were further classified into types B and C. In type B, the affected fold remained thin during phonation and inhalation (n = 12). Type C was allocated to those showing one or two paradoxical movements of the affected fold (n = 15). Those with type A showed significantly better vocal function.

Laryngeal Reinnervation Featuring Refined Nerve-Muscle Pedicle Implantation Evaluated via Electromyography and Use of Coronal Images:

Objective To evaluate the long-term efficacy of laryngeal reinnervation via refined nerve-muscle pedicle (NMP) flap implantation combined with arytenoid adduction to treat unilateral vocal fold paralysis (UVFP), employing laryngeal electromyography (LEMG), coronal imaging, and phonatory function assessment. Study Design Case series with chart review. Setting University hospital. Subjects and Methods We retrospectively reviewed 12 UVFP patients who underwent refined NMP implantation with arytenoid adduction. Videostroboscopy, phonatory functional analysis, LEMG, and coronal imaging were performed before and 2 years after surgery. In LEMG analysis, a 4-point scale was employed to grade motor unit (MU) recruitment: 4+ reflected no recruitment, 3+ greatly decreased recruitment, 2+ moderately decreased recruitment, and 1+ mildly decreased activity, associated with less than the full interference pattern. Coronal images were assessed in terms of differences in thickness and the vertical positions of the vocal folds. Results Phonatory function improved significantly after operation in all patients. In terms of LEMG findings, the preoperative MU recruitment scores were 1+ in no patients, 2+ in 4 patients, 3+ in 1 patient, and 4+ in 7 patients. Postoperative MU recruitment results were 1+ in 6 patients, 2+ in 5 patients, 3+ in 1 patient, and 4+ in no patients. Thinning of the affected fold during phonation was evident preoperatively in 9 of 10 patients. The affected and healthy folds were equal in volume in 4 of 9 patients postoperatively. Conclusion The LEMG findings and coronal imaging suggest that NMP implantation may have enabled successful reinnervation of the laryngeal muscles of UVFP patients.

Modulation of satellite cells activity and MyoD in rat thyroarytenoid muscle after reinnervation.

To examine modulation of M‐cadherin, a marker for satellite cells (SCs); and MyoD, which may indicate the myogenic activity following recurrent laryngeal nerve (RLN) denervation and immediate reinnervation; and to elucidate the correlation between their modulations and establishment of neuromuscular junctions (NMJs) in the reinnervated rat thyroarytenoid (TA) muscle.

Laryngeal Muscle Activity in Unilateral Vocal Fold Paralysis Patients Using Electromyography and Coronal Reconstructed Images

Objective To assess laryngeal muscle activity in unilateral vocal fold paralysis (UVFP) patients using laryngeal electromyography (LEMG) and coronal images. Study Design Case series with chart review. Setting University hospital. Subjects and Methods Twenty-one patients diagnosed with UVFP of at least 6 months in duration with paralytic dysphonia, underwent LEMG, phonatory function tests, and coronal imaging. A 4-point scale was used to grade motor unit (MU) recruitment: absent = 4+, greatly decreased = 3+, moderately decreased = 2+, and mildly decreased = 1+. Maximum phonation time (MPT) and mean flow rate (MFR) were employed. Coronal images were assessed for differences in thickness and vertical position of the vocal folds during phonation and inhalation. Results MU recruitment in thyroarytenoid/lateral cricoarytenoid (TA/LCA) muscle complex results were 1+ for 4 patients, 2+ for 5, 3+ for 6, and 4+ for 6. MPT was positively correlated with MU recruitment. Thinning of the affected fold was evident during phonation in 19 of the 21 subjects. The affected fold was at an equal level with the healthy fold in all 9 subjects with MU recruitment of 1+ and 2+. Eleven of 12 subjects with MU recruitments of 3+ and 4+ showed the affected fold at a higher level than the healthy fold. There was a significant difference between MU recruitment and the vertical position of the affected fold. Conclusions Synkinetic reinnervation may occur in some cases with UVFP. MU recruitments of TA/LCA muscle complex in UVFP patients may be related to phonatory function and the vertical position of the affected fold.

Recurrent Laryngeal Nerve Regeneration through a Silicone Tube Produces Reinnervation without Vocal Fold Mobility in Rats

Objectives: We established an animal model of recurrent laryngeal nerve reinnervation with persistent vocal fold immobility following recurrent laryngeal nerve injury. Methods: In 36 rats, the left recurrent laryngeal nerve was transected and the stumps were abutted in a silicone tube with a 1-mm interspace, facilitating regeneration. The mobility of the vocal folds was examined endoscopically 5, 10, and 15 weeks later. Electromyography of the thyroarytenoid muscle was performed. Reinnervation was assessed by means of a quantitative immunohistologic evaluation with anti-neurofilament antibody in the nerve both proximal and distal to the silicone tube. The atrophy of the thyroarytenoid muscle was assessed histologically. Results: We observed that all animals had a fixed left vocal fold throughout the study. The average neurofilament expression in the nerve both distal and proximal to the silicone tube, the muscle area, and the amplitude of the compound muscle action potential recorded from the thyroarytenoid muscle on the treated side increased significantly (p < 0.05) over time, demonstrating regeneration through the silicone tube. Conclusions: Recurrent laryngeal nerve regeneration through a silicone tube produced reinnervation without vocal fold mobility in rats. The efficacy of new laryngeal reinnervation treatments can be assessed with this model.

Over-adduction of the unaffected vocal fold during phonation in the unilaterally paralyzed larynx

Abstract Conclusions: Over-adduction of the unaffected vocal fold may not compensate vocal function in unilateral vocal fold paralysis (UVFP). Objective: To determine whether over-adduction of the unaffected vocal fold has any impact on vocal function in patients with UVFP. Methods: A total of 101 patients with UVFP who underwent three-dimensional computed tomographic (CT) examination of the larynx served as subjects. Three-dimensional endoscopic images together with coronal images during phonation were produced to evaluate over-adduction of the unaffected fold, posterior glottal gap, and differences in the vertical position and thickness between the vocal folds. Maximum phonation time (MPT) and mean airflow rate (MFR) were measured. Results: In all, 47 patients showed over-adduction. Their MPT and MFR were 4.9 ± 2.9 s and 653 ± 504 ml/s, respectively. The remaining 54 did not show over-adduction. Their MPT and MFR were 4.7 ± 2.7 s and 574 ± 384 ml/s, respectively. There were no significant differences in MPT or MFR between the two groups. Of the 47 patients with over-adduction, 9 showed no posterior glottal gap. However, their vocal function was not significantly different from that of 38 patients with posterior glottal gap or from that of 43 patients without over-adduction and having a posterior glottal gap.

Potential treatment for vocal fold scar with pirfenidone: Pirfenidone for Vocal Fold Scar

Pirfenidone (PFD) is a strong antifibrotic agent that has been clinically approved in Japan for idiopathic pulmonary fibrosis. We examined the antifibrotic effects of PFD on fibroblasts isolated from scarred vocal folds (VFs) of ferrets in vitro.

Paradoxical movement of rat vocal folds following recurrent laryngeal nerve injury.

Abstract Objective: To establish a rat model with paradoxical vocal fold movement to understand the detailed etiology and physiology of laryngeal synkinesis by evaluating vocal fold movement and by electromyography. Methods: Adult Wistar rats were used. The recurrent laryngeal nerve was transected, anastomosed, and the anastomotic portion was placed in a silicone tube. At 2, 4, and 10 weeks after the treatment (n = 30), we performed laryngoscopy and electromyography. The vocal fold movement was recorded, the hemiglottal area was measured, and the Δarea was calculated by subtracting the area during expiration from that during inhalation. We evaluated the ratio of the Δarea on the treated side to that of the normal side. After laryngoscopy, electromyography of the thyroarytenoid and posterior cricoarytenoid muscles was performed. Results: The mean Δareas were 1.5 ± 3.4%, 2.3 ± 21.5%, and 0.7 ± 31.8% at 2, 4, and 10 weeks after anastomosis, respectively. Eighteen of 18 rats indicated synkinetic reinnervation at 4 and 10 weeks. Regarding vocal fold mobility, 8 of 18 animals showed paradoxical movement, and 5 of 18 exhibited impaired mobility. Conclusion: We have established an animal model of paradoxical movement following recurrent laryngeal nerve injury. This model may be useful in studying laryngeal synkinesis.