Yutaka Toya

Nerve-muscle pedicle flap implantation combined with arytenoid adduction

OBJECTIVES To describe a new technique of nerve-muscle pedicle (NMP) flap implantation combined with arytenoid adduction (AA) to treat dysphonia due to unilateral vocal fold paralysis and to examine postoperative vocal function. STUDY DESIGN Retrospective review of clinical records. SETTING Tertiary academic center. PATIENTS Twenty-two consecutive patients underwent NMP flap implantation with AA and were followed up short term over a period of 1 to 6 months (mean, 2.9 months) and long term over a period of 7 to 36 months (mean, 21.4 months). INTERVENTIONS An NMP flap was made using an ansa cervicalis branch and a piece of the sternohyoid muscle. A window was opened in the thyroid ala at the level of the vocal fold. Then, AA was performed and the NMP flap was securely implanted onto the thyroarytenoid muscle through the window under microscopic guidance. MAIN OUTCOME MEASURES The maximum phonation time, mean airflow rate, pitch range, and acoustic parameters (jitter, shimmer, and harmonics to noise ratio) were evaluated before surgery and twice after surgery. RESULTS All parameters improved significantly after surgery (P < .01). The measurements for maximum phonation time, mean airflow rate, and harmonics to noise ratio were within normal ranges after surgery. Furthermore, the maximum phonation time and jitter were significantly improved after long-term follow-up compared with early postoperative measurements (P < .01 and P < .05, respectively). CONCLUSIONS Precise harvest of an NMP flap and its placement directly onto the thyroarytenoid muscle combined with AA provided excellent vocal function. The NMP method may have played a certain role in the improvement of postoperative vocal function, although further study with electromyographic examination is required to clarify the innervation status of the thyroarytenoid muscle.

Videolaryngoscopic assessment of laryngeal edema after arytenoid adduction.

Arytenoid adduction (AA) as surgical treatment for unilateral vocal fold paralysis (UVFP) is associated with higher morbidity from airway complications due to postoperative laryngeal edema compared with other laryngeal framework surgeries. The aim of this study was to evaluate postoperative laryngeal edema after AA using a new videolaryngoscopic (VL) scoring assessment.

Modulation of nerve fibers in the rat thyroarytenoid muscle following recurrent laryngeal nerve injury

Abstract Conclusion. Regeneration of nerve fibers in the thyroarytenoid (TA) muscle occurred actively after damage on the recurrent laryngeal nerve (RLN) compared with the vagus nerve (VN). However, remyelination did not occur after damage on the RLN. Objectives. To determine the regeneration process of nerve fibers in the TA muscle following transection and immediate anastomosis of the RLN or VN. Methods: Three types of animal model were prepared: an RLN anastomosis model (RLNa), a VN anastomosis model (VNa), and a peroneal nerve anastomosis model (PNa). Animals were sacrificed at five time points following the procedure. The modulation of axons, myelin sheaths, Schwann cells (SCs), nerve terminals (NTs), and acetylcholine receptors (AchRs) in the TA or tibialis anterior muscles was examined by immunohistochemical analysis. The ratios of the expression areas in axons, myelin sheaths, and SCs, and the number of NTs and AchRs in the treated (T) and untreated (U) sides (T/U) were evaluated. Results: At 18 weeks, the T/U ratios of expression in RLNa, VNa, and PNa were 68.5, 0, and 100.4%, respectively, in axons; 0, 0, and 97.6% in myelin sheaths; 53.7, 0, and 93.6% in SCs; 61.0, 0, and 96.4% in NTs; and 99.4, 67.0, and 101.2% in AchRs.

Voice tuning with new instruments for type II thyroplasty in the treatment of adductor spasmodic dysphonia

OBJECTIVE Adductor spasmodic dysphonia is a rare voice disorder characterized by strained and strangled voice quality with intermittent phonatory breaks and adductory vocal fold spasms. Type II thyroplasty differs from previous treatments in that this surgery does not involve any surgical intervention into the laryngeal muscle, nerve or vocal folds. Type II thyroplasty intervenes in the thyroid cartilage, which is unrelated to the lesion. This procedure, conducted with the aim of achieving lateralization of the vocal folds, requires utmost surgical caution due to the extreme delicacy of the surgical site, critically sensitive adjustment, and difficult procedures to maintain the incised cartilages at a correct position. During surgery, the correct separation of the incised cartilage edges with voice monitoring is the most important factor determining surgical success and patient satisfaction. METHODS We designed new surgical instruments: a thyroid cartilage elevator for undermining the thyroid cartilage, and spacer devices to gauge width while performing voice monitoring. These devices were designed to prevent surgical complications, and to aid in selecting the optimal size of titanium bridges while temporally maintaining a separation during voice monitoring. RESULTS We designed new surgical instruments, including a thyroid cartilage elevator and spacer devices. Precise surgical procedures and performing voice tuning during surgery with the optimal separation width of the thyroid cartilage are key points for surgical success. CONCLUSION We introduce the technique of voice tuning using these surgical tools in order to achieve a better outcome with minimal surgical complications.

Changes in respiratory function after thyroplastic surgery.

Conclusions. A certain degree of subclinical extrathoracic airway compromise may ensue after thyroplastic surgery, although none of the patients reported the presence of dyspneic symptoms in their normal daily lives. Objectives: To determine the effects of thyroplastic surgery on respiratory function and compare them with the improvement of vocal function. Patients and methods: The study included 53 patients; 7 had type I thyroplasty (type I), 9 had arytenoid adduction (AA), 10 had AA with type I, and 27 had AA with neuromuscular pedicle flap implantation (NMP). Phonatory and respiratory functions were measured preoperatively and postoperatively. The presence of dyspnea during daily activities was determined postoperatively. Results: The difference between the pre- and postoperative values was statistically significant in five comparisons. Forced expiratory volume in 1 s/forced expiratory volume (FEV1%) in the AA with type I group, FEV1/peak expiratory flow rate (PEFR) in the AA group, and PEFR in the three groups (type I, AA, and AA with NMP). Forty-six patients associated with AA were combined for statistical analysis. The differences were statistically significant for FEV1%, PEFR, and FEV1/PEFR. Changes in maximum phonation time (MPT) were found to have a significant correlation with changes in FEV1/PEFR. All the patients denied episodes of dyspnea during their normal daily activities.

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.

The Ferret as a Surgical Model for Vocal Fold Scar Creation and Treatment

Objectives: To develop a vocal fold (VF) scarring procedure in the ferret, characterize the scars histologically, and test the injectability of the lamina propria (LP). Secondarily, to compare laryngeal anatomy of the ferret with rat and rabbit. Materials and Methods: The larynges of 18 male ferrets were prepared by unilateral scarring, and normal larynges from 6 female Wistar rats and 5 male albino rabbits were used for comparative purposes. For scarring, the right VF were electrocauterized, ablating the entire LP. Prior to harvesting the larynges at 4 and 16 weeks, each ferret was re-anesthetized, and in 3 animals, India ink was injected into the LPs of both normal and scarred VFs. Results: Laryngoscopic methods and instrumentation for precise visualization, scarring, and injection were developed. The scarred VFs had reduced hyaluronic acid and increased collagen type I, III, and fibronectin compared with normal VFs. The 2 timepoints (4 and 16 weeks) differed significantly only in collagen type III level (levels were higher at 4 weeks). Injected ink migrated from scarred LP to muscle layer just beneath the scarred tissue 3 hours after injection. Conclusion: The ferret is a promising species for creation and experimental treatment of vocal fold scar.

Nerve Fibers in Laryngeal Muscle Following Injury on Nerve

Objective: Compare the modulation of nerve fibers, 1) between recurrent laryngeal nerve (RLN) and vagus nerve (VN) in the thryroarytenoid (TA) muscle, 2) between RLN in TA and peroneal nerve (PN) in tibialis anterior (TbA) muscle following nerve section and immediate anastomosis using rat model. Method: Rats were sacrificed at 5 occasions after nerve section followed by anastomosis. Axons, myelin sheaths, Schwann cells, nerve terminals, and acetylcholine receptors in TA and TbA were quantified by immunohistochemistry. Data were expressed as the ratio between treated and untreated sides (T/U ratio). Results: Eighteen weeks posttreatment, the mean T/U ratios for axon expression were RLN: 68.5%, VN: 0.0% and PN: 99.2%; the ratios for myelin sheath were RLN: 0.0%, VN: 0.0%, PN: 97.6%; the ratios for Schwann cells were RLN: 53.7%, VN: 0.0%, and PN: 93.6%; the ratios for nerve terminals were RLN: 61.0%, VN: 0.0%, and PN:96.4%; and the ratios for acetylcholine receptors were almost 100% for RLN and PN and 67.2% for VN. For all measurements there was a significant difference between RLN and PN at the 18 weeks time point (P < .001). Conclusion: These results show that, at 18 weeks, regeneration did not occur in VN. On the other hand, regeneration occurred in both RLN and PN, moreover, nerve fibers were more matured in PN compared to RLN.

A New Classification of Laryngeal Synkinesis

Objective: 1) Develop a new classification of laryngeal synkinesis in patients with unilateral vocal fold paralysis (UVFP) based on images of the vocal fold using 3-dimensional computed tomography (3DCT) 2) Compare synkinesis type based on 3DCT image analysis with recruitment in electromyography during phonation. Method: Retrospective. Subjects included 50 patients with UVFP who underwent framework surgeries between 2000 and 2010. Three-dimensional images during phonation and inhalation preoperatively were assessed focusing on thickness of the affected fold to classify synkinesis. Recruitment of thyroarytenoid muscle was rated and compared with synkinesis type. Results: Two subjects were excluded because of poor performance during scanning. Three synkinesis types were identified. The affected fold in 12 subjects showed some degree of thickening during phonation. The affected fold of the remaining 36 was thin during phonation. Thickening of the affected fold was evident during inhalation in 20 of the 36 subjects, while the affected fold in the rest (16 subjects) remained to be thin. Thirty-one subjects underwent electromyography. Those with the latter 2 types of synkinesis had a tendency of less recruitment compared with those with the former type of synkinesis. Conclusion: The use of the new classification of laryngeal synkinesis facilitates understanding of behavior of the affected vocal fold in patients with UVFP. The number of subjects who underwent electromyography was not sufficient to draw a conclusion about the relation between synkinesis classification and recruitment.