Perceptual, aerodynamic and acoustic outcomes of surgical technique for sulcus vocalis patients: A systematic review and meta analysis

BACKGROUND

Sulcus Vocalis (SV) is a voice disorder characterized by the parallel invagination of the vocal fold epithelium that adheres to the vocal ligament. This condition disrupts the vibratory function, leading to glottal incompetence, hoarseness, and vocal impairment. Despite various proposed surgical techniques, a standardized treatment approach remains elusive.

METHODS

We conducted a comprehensive search across PubMed/Medline, Embase, Web of Science, Scholar, and the Cochrane Library for studies on SV treatment. The inclusion criteria comprised original studies comparing pre- and post-treatment vocal outcomes in SV patients, published in English. We excluded case reports, reviews, studies without continuous data, and patients with vocal scar/atrophy.

RESULTS

Fifteen observational studies were included (361 patients, 53.73 % male, average age 41.64 years). 80 % of these studies employed self-reported outcomes, while 81.25 % analyzed acoustic/aerodynamic data. The follow-up period varied from 4 to 44 months. All techniques significantly improved Voice Handicap Index (VHI) scores (p < 0.001). Dissective and combined techniques exhibited greater reductions in VHI-30/10 (p < 0.001). Maximum Phonation Time (MPT) improved significantly across all techniques (p < 0.001), with dissective techniques demonstrating superior MPT outcomes (p < 0.001). Jitter improved significantly for dissective and injective techniques (p < 0.001), as did Shimmer for all techniques (p < 0.001). Notably, combined techniques displayed the most significant reductions (p < 0.001).

CONCLUSIONS

Surgical treatments significantly improve subjective, aerodynamic, and acoustic outcomes in SV patients. Dissective and combined dissective/injective techniques appear to yield better perceptual and phonatory outcomes compared to injective techniques alone. Further research is necessary to establish the optimal treatment approach for SV.

Evaluating Interventions for Sulcus Vocalis or Vocal Fold Scar: A Systematic Review and Meta-analysis

BACKGROUND

Sulcus vocalis reflects varying degrees of vocal cord lamina propria (LP) damage. Many interventions have been discussed in the literature for addressing sulcus vocalis, but there is no universally accepted gold standard for its management.

AIM

We aim in our study to collectively evaluate the effectiveness of different relevant interventions in the literature used for sulcus vocalis or vocal fold scar.

METHODS

We searched five electronic databases to collect all relevant studies. Records were screened for eligibility. Data were extracted from the included studies independently. Our continuous outcomes were pooled in our single-arm meta-analysis as mean change (MC) and with 95% confidence interval (CI).

RESULTS

Our systematic review and meta-analysis included 43 studies encompassing 1302 patients. The jitter parameter indicated that laser degeneration and LP regeneration/scar degradation led to the highest improvements compared to their baseline, with pooled MC of -0.897 and -0.893, respectively. Graft interposition showed a MC of -0.848, while medialization and dissection had less pronounced changes at -0.200. Shimmer parameter results were similar, with medialization and laser degeneration leading to MC of -2.129 and -2.123, while LP regeneration/scar degradation and graft interposition showed smaller changes MC -1.530 and -1.217. For the noise-to-harmonic ratio (NHR) parameter, LP regeneration/scar degradation demonstrated MC = -0.028. In aerodynamics outcomes, graft interposition and LP regeneration/scar degradation showed the highest MCs in mean phonatory time (MPT) (4.214 and 3.467, respectively). Endoscopic outcomes for mucosal wave showed high improvements in medialization and graft interposition (MC = 10.40 and 10.18, respectively). Perceptual outcomes favored graft interposition in various parameters, while laser degeneration performed well in most categories. Graft interposition and LP regeneration/scar degradation had a high voice handicap index (VHI) (MC = -27.195 and -19.269, respectively).

CONCLUSION

Laser degeneration and LP regeneration/scar degradation were particularly effective in improving acoustic parameters. In aerodynamics, graft interposition and LP regeneration/scar degradation improved vocal efficiency compared to their baselines. Medialization and laser degeneration had the largest impact compared to their baseline on shimmer and MPT. Endoscopic assessments showed that medialization and graft interposition had high improvement in mucosal waves, and perceptual outcomes were generally high with graft interposition and laser degeneration.

Treatment efficacy of 532-nm diode laser glottoplasty in patients with sulcus vocalis: a prospective study

PURPOSE

This study prospectively assessed the efficacy and safety of 532-nm diode laser glottoplasty in patients with sulcus vocalis.

METHODS

A prospective human trial was performed from August 2016 to September 2021. 532-nm diode laser glottoplasty was performed in 30 consecutive patients with sulcus vocalis who suffered from voice problems. Patients underwent acoustic aerodynamic, perceptual, stroboscopic, and Voice Handicap Index-10 (VHI-10) evaluations before and 1, 6, and 12 months after laser glottoplasty.

RESULTS

Most subjective parameters showed significant improvement (P < 0.05) at 6 months after laser glottoplasty and remained stable at 12 months. Most objective parameters showed significant improvement (P < 0.05) at 12 months after laser glottoplasty. Complications during follow-up included mild vocal fold vibration reduction in 3.3% of patients (1/30) and persistent vocal fold edema in 3.3% of patients (1/30).

CONCLUSIONS

Statistically significant voice improvement at 12 months after 532-nm diode laser glottoplasty was achieved without serious complications.

Pre and Post-operative Voice Therapy Intervention for Benign Vocal Fold Lesions: A Systematic Review

Benign vocal fold lesions cause dysphonia by preventing vocal fold closure, causing irregular vibration and increasing compensatory muscle tension. Voice therapy delivered in addition to phonosurgery may improve voice and quality of life outcomes but the evidence base is lacking and what constitutes voice therapy for this population is not defined. The purpose of this systematic review is to critically evaluate the evidence for pre and post-operative voice therapy to inform the development of an evidence based intervention.

STUDY DESIGN

Systematic Review.

METHODS

Electronic databases were searched using key terms including dysphonia, phonosurgery, voice therapy and outcomes. Eligible articles were extracted and reviewed by the authors for risk of bias and for information regarding the content, timing and intensity of any pre and post-operative voice therapy intervention.

RESULTS

Of the 432 articles identified, 35 met the inclusion criteria and were included in the review. 5 were RCTs, 2 were individual cohort studies, 1 was a case control study and 26 were case series. There was considerable heterogeneity in participant characteristics. Information was frequently lacking regarding the content timing and intensity of the reported voice therapy intervention, and where present, interventions were highly variable.

CONCLUSION

Reporting in relevant literature is limited in all aspects of content, timing and intensity of intervention. Further intervention development work is required to develop a robust voice therapy treatment intervention for this population, before effectiveness work can commence.

Duration of Clinical Response After In-Office Steroid Injection for Vocal Fold Scar

OBJECTIVE

To assess the duration of clinical response after in-office vocal fold steroid injection (VFSI) for vocal fold (VF) scar.

METHODS

Demographic and clinical data for in-office VFSI occurring from 2017 to 2020 were collected. Two Speech-Language Pathologists (SLPs) used perceptual evaluation of voice and functional scales to evaluate blinded voice and laryngovideostroboscopy (LVS) samples collected pre- and post-injection across multiple timepoints.

RESULTS

Blinded SLP ratings were used for 30 individual VFs undergoing initial injection in 18 patients. Persistent improvement in voice past 6 months was seen in 57% of patients after VFSI. Multiple measures of voice and amplitude, percent vibrating tissue, and closed phase predominance significantly improved at various follow-up timepoints on average.

CONCLUSION

Accounting for patient heterogeneity and disease progression, in-office VFSI for VF scar is associated with sustained improvement in a subset of patients. Approximately half of patients can expect to experience a lasting improvement in voice. Future studies of larger scale are required to identify patient factors associated with long-term benefit.

LEVEL OF EVIDENCE

4 Laryngoscope, 133:2333-2339, 2023.

Assessment of Subjective and Objective Voice Analysis According to Types of Sulcus Vocalis

INTRODUCTION

Sulcus vocalis (SV) subtypes are difficult to diagnose. Non-invasive techniques are sometimes not feasible in the diagnosis. The study aims to demonstrate the effectiveness and applicability of objective and subjective voice analysis combined with videolaryngostroboscopic examination (VLS) in the diagnosis of SV types.

MATERIAL AND METHODS

This is a retrospective study that includes patients who presented to Phoniatric outpatient clinic with complaints related to voice and diagnosed with SV on VLS examination between 2017-2020. The SV type was determined based on VLS findings and the patients were categorized into respective groups. Between- and within-group assessment of objective and subjective voice analysis of SV types was conducted.

RESULTS

47 patients were included in the study; Type I, Type II, Type III SV patients were 16, 17, and 14 in number, respectively. Fundamental frequency (F0) and Shimmer (%) values were significantly high in Type II and III SV cases, whereas the Maximum Phonation Time (MPT) was significantly low. GRBAS, Voice Handicap Index -10 (VHI-10), Reflux Symptom Index (RSI) scores were statistically significantly high in pathological SV and Voice Related Quality of Life (V-RQOL) scores were low. A moderate correlation between VHI-10 and V-RQOL and between RSI and V-RQOL was detected.

CONCLUSIONS

Objective and subjective voice analysis in Type II and III SV show a significant difference compared to Type I SV. The use of objective and subjective voice analysis combined with VLS examination can be helpful in the diagnosis of SV types.

Platelet-Rich Plasma for Vocal Fold Scar: A Preliminary Report of Concept

INTRODUCTION

Vocal fold atrophy and scar can lead to loss of normal superficial lamina propria, negatively affecting the vibratory function of the vocal fold. These changes can lead to dysphonia, vocal fatigue, decreased volume, and altered pitch. Treatment options for these conditions are limited. Platelet-rich plasma (PRP) consists of platelets, growth factors, and cytokines derived from the patient's own blood and is believed to activate tissue regeneration. The purpose of this study was to review the technical aspects of collecting PRP and injecting it into the vocal fold injection - based on our initial experience with this procedure.

CASE

A patient with vocal fold scar was identified and enrolled in an ongoing prospective clinical trial study of a series of 4 monthly subepithelial vocal fold PRP injections, which was temporarily halted due to the COVID-19 pandemic. Patient underwent a single injection of autologous PRP into the left vocal fold. There were no adverse events during the study period. Subjective improvement in voice was noted at 1 month after injection with subsequent return to baseline over the next 4 months. Videostroboscopy performed on postinjection day 1 and day 7 and demonstrated no concerning exam changes. Compared to the preinjection baseline, the patient-reported voice-handicap index-10 (VHI-10) and voice catastrophization index were similar at 4 months following injection (20 to 20 and 4 to 3, respectively). Independent perceptual analysis of voice showed improvement at 4 months postinjection, compared to baseline consensus auditory-perceptual evaluation of voice 60 to 44.

CONCLUSIONS

This preliminary report was part of a prospective trial investigating the use of PRP to treat vocal fold atrophy and scar. This work highlights the technical considerations for injecting PRP into the vocal fold. Planned prospective enrollment in this study will help to validate the safety and efficacy of PRP injections.

Intracordal injection therapy for vocal fold scarring: Steroid versus basic fibroblast growth factor

Objectives

Vocal fold scarring is caused by replacement of vocal fold mucosa with fibrous tissue due to repeated inflammation or trauma. It can lead to severe dysphonia. It is currently treated conservatively and with phonosurgery and intracordal injections. Intracordal injection of steroid or basic fibroblast growth factor (bFGF) has been recently found to be useful for treating vocal fold scarring that does not respond to voice therapy.

Methods

This retrospective study involved the administration of steroid injection and bFGF injection bilaterally under local anesthesia in 16 patients each. Laboratory measurements of voice parameters were performed before and 3-6 months after injection.

Results

In the steroid injection group, the Voice Handicap Index (VHI) score significantly improved from 57.1 to 40.5, total Grade, Roughness, Breathiness, Asthenia, Strain (tGRBAS) score significantly improved from 4.2 to 2.6, and mean speech fundamental frequency (SFF) increased from 192.5 to 211.4 dB, but there was no improvement in maximum phonation time (MPT) and mean airflow rate (MFR). In the bFGF injection group, significant improvements in the VHI score (from 53.3 to 35.7), MPT (from 16.9 to 21.8 s) and MFR (from 314.6 to 210.5 ml/s) were seen; however, the tGRBAS score did not improve. In addition, the SFF significantly decreased from 178.1 to 160.5 Hz.

Conclusion

These results suggest that both steroid and bFGF injections are effective for treating vocal fold scarring, with steroids improving voice quality and bFGF improving glottic closure, thereby contributing to improvements in VHI scores.

Level of Evidence

4.

Vocal fold sulci - what are the current options for and outcomes of treatment?

PURPOSE OF REVIEW

Sulcus vocalis is a benign condition of the vocal folds that, according to its severity, can affect the quality of the voice of those who have it. Voice symptoms can range from mild to severe, affecting the quality of life of patients with this condition. Although different surgical and no surgical options have been described, no gold standard treatment has been described.

RECENT FINDINGS

New evidence supports congenital, inflammatory, and acquired theories for sulcus vocalis. Also, recent literature demonstrated the role of the epithelium in the pathogenesis, which makes the absence of superficial lamina propria no longer the only accepted hypothesis. Technological developments improved the in-office diagnostics capabilities for this condition, but vocal fold palpation remains the gold standard. Different benign laryngeal conditions are associated with sulcus vocalis and knowing when to treat those is very important. Different treatment options are available for sulcus vocalis, however, results are diverse and no strong recommendations for one over the other can be made.

SUMMARY

Progress continues to be made in our understanding of sulcus vocalis from diagnosis to treatment. Novel and promising therapeutic strategies have been recently developed for this condition; however, more data and investigations are needed to improve their accuracy and reproducibility.

Minor Structural Alterations of the Vocal Fold Cover: Vocal Quality before and after Treatment

Introduction  Minor structural alterations of the vocal fold cover are important causes of dysphonia. The variability in the type of alteration and the grade of vocal deviation affects the definition of the conduit and the results of treatment. Objective  To characterize the occurrence, the selected treatments adopted and vocal quality before and after treatment in patients with minor structural alterations of the vocal folds cover. Methods  This was a cross-sectional study based on the records of patients treated by an interdisciplinary team at the laryngology outpatient clinic of a public university hospital from 2010 to 2018. Data collection consisted of access to a database of information on otorhinolaryngological diagnostic hypotheses, intervention and perceptual-auditory vocal assessments before and after the treatment. Data from 102 subjects were analyzed. Association tests were applied between the perceptual-auditory vocal results and the different alterations found and between these and the adopted treatments. The results of the degrees of vocal deviation before and after treatment were also compared. Results  The degree of roughness was associated with the sulcus vocalis, and in this alteration the highest occurrence was mild degree of roughness. There was an improvement in the breathiness and general grade of vocal deviation after treatment. Conclusion  Cysts were the most frequent structural alteration in the population studied. There was an association between the degree of general deviation and that of roughness in sulcus vocalis cases. The breathiness and the general grade of vocal deviation improved after treatment regardless of the type of treatment and alteration.

Hoarseness

Hoarseness is a common problem, typically of transient nature. When hoarseness does not resolve, or when it is associated with concerning symptoms, it is important to consider a wide differential and refer to an otolaryngologist. This article discusses the physiology of the voice and possible causes of dysphonia, and explores when it warrants further work-up by ENT. A discussion of diagnostic techniques and the myriad of tools to treat hoarseness follows. Additionally, the role of reflux in dysphonia is examined with a critical eye to aid in accurate assessment of the patient's complaint.

A Systematic Review on Surgical Treatments for Sulcus Vocalis and Vocal Fold Scar

OBJECTIVES/HYPOTHESIS

Vocal fold sulcus and scars are benign vocal fold lesions that present as a challenge to the laryngologist. A number of different surgical techniques have been proposed, aiming at restoring the lamina propria (LP), closing the glottal gap, or both. This study aimed to provide a systematic review of surgical treatment for sulcus and scar and to propose a new classification for these techniques.

STUDY DESIGN

A literature search using MEDLINE and Google Scholar through August 2020.

METHODS

Data on study design were retrieved and outcomes were classified as acoustic, aerodynamic, self-reported, perceptual, and stroboscopic. Methodological quality was assessed using the MINORs criteria. Each technique was classified as direct, indirect, or combined.

RESULTS

Our search included 31 studies with a total of 617 patients. Direct techniques included dissection, graft interposition, or LP regeneration/scar degradation while indirect techniques aimed for glottal gap closure. Only one article performed a comparison between different types of techniques and only eight studied the five types of outcomes. No superiority of any technique was noted in our analysis. Self-reported outcomes were the most frequently improved.

CONCLUSIONS

There seems to not exist a one-fits-all treatment for this clinical picture and no clear decision-making pattern. A recent trend toward sequential approaches, starting with less invasive procedures, can be observed. Laryngoscope, 2021.

Bilateral medialization thyroplasty in patients with vocal fold atrophy with or without sulcus

Purpose

To evaluate voice outcome after bilateral medialization thyroplasty in patients with non-paralytic glottic insufficiency due to vocal fold atrophy with or without sulcus.

Methods

Retrospective cohort study on 29 patients undergoing bilateral medialization thyroplasty for vocal fold atrophy (14 procedures) or atrophy with sulcus (15 procedures) between October 2012 and November 2017. Voice data were collected and analyzed for the preoperative and the 3- and 12-month postoperative time point according to a standardized protocol, including Voice Handicap Index (VHI)-30 and perceptual, acoustic and aerodynamic parameters. Failure rate was based on number of revisions within 12 months and non-relevant improvement (< 10 points) in VHI-30 at 12 months.

Results

There was a clinically relevant (≥ 15 points) and statistically significant improvement (p < 0.0001) in the VHI-30 (preoperative: 55.8 points; postoperative at 12 months: 30.9 points). Fundamental frequency for male subjects decreased significantly from 175 to 159 Hz (p = 0.0001). The pre- and post-operative grade of dysphonia was significantly lower in patients with atrophy compared to atrophy and sulcus (mean difference 0.70, p = 0.017).

Conclusion

Bilateral medialization thyroplasty is a valid treatment option for patients with atrophy with or without sulcus. Outcomes are comparable to other methods reported in literature. However, there is a great need for larger, prospective studies with long-term follow-up to gain more insight into the comparative voice outcomes for the different forms of surgery for patients with glottic incompetence due to atrophy with or without sulcus.

Autologous fibroblasts for vocal scars and age-related atrophy: A randomized clinical trial

OBJECTIVES/HYPOTHESIS

To assess the safety and efficacy of autologous cultured fibroblasts (ACFs) to treat dysphonia related to vocal fold scar and age-related vocal atrophy (ARVA).

STUDY DESIGN

Randomized, double-blinded, placebo-controlled, multi-institutional, phase II trial.

METHODS

ACFs were expanded from punch biopsies of the postauricular skin in each subject; randomization was 2:1 (treatment vs. placebo). Three injections of 1-2 × 10⁷ cells or placebo saline was performed at 4-week intervals for each vocal fold. Follow-up was performed at 4, 8, and 12 months. The primary outcome was improved mucosal waves. Secondary outcomes included Voice Handicap Index (VHI)-30, patient reported voice quality outcomes, and perceptual analysis of voice.

RESULTS

Fifteen subjects received ACF and six received saline injections. At 4, 8, and 12 months after ACF treatments, a significant improvement in mucosal wave grade relative to baseline was observed in both vocal scar and ARVA groups. Relative to control group, mucosal waves were significantly improved in the ARVA group at 4 and 8 months. Perceptual analysis significantly improved in the vocal scar group 12 months after ACF treatments compared to controls. Vocal scar group reported significantly improved vocal quality from baseline. VHI and expert rater voice grade improved in both groups, but did not achieve significance. No adverse events related to fibroblast injections were observed.

CONCLUSIONS

In this cohort, injection of ACFs into the vocal fold lamina propria (LP) was safe and significantly improved mucosal waves in patients with vocal scar and ARVA. ACF may hold promise to reconstruct the LP.

LEVEL OF EVIDENCE

1 Laryngoscope, 130:2650-2658, 2020.

Bilateral vocal fold injection with autologous fat in patients with vocal fold atrophy with or without sulcus

Purpose

To evaluate voice outcome after bilateral vocal fold injection with autologous fat in patients with non-paralytic glottic insufficiency due to vocal fold atrophy with or without sulcus.

Methods

This is a retrospective cohort study from September 2012 to December 2017 including 23 patients undergoing bilateral vocal fold injection with autologous fat (24 procedures) for vocal fold atrophy (15 procedures) or atrophy with sulcus (Ford type II or III) (9 procedures). Voice data were collected and analyzed for the preoperative and the 3- and 12-month postoperative time points according to a standardized protocol, including Voice Handicap Index (VHI)-30 and perceptive, acoustic and aerodynamic parameters. Failure rate was defined as non-relevant improvement (< 10 points) in VHI-30 at 12 months and number of revisions within 12 months.

Results

There was a clinically relevant (≥ 15 points) and statistically significant improvement in the VHI-30 (preoperative: 49.1 points; postoperative at 12 months: 29.7 points). Change in dynamic range was also statistically significant over time (p = 0.028). There were no differences in voice parameters between patients with atrophy only and atrophy with sulcus, although grade tended to be lower in patients with atrophy only over all time points.

Conclusion

This study shows that bilateral vocal fold injection with autologous fat is a beneficial treatment not only for patients with atrophy but also for patients with sulcus. A comparison of the results with those reported from other forms of sulcus surgery confirmed this finding. However, there is a need for further prospective studies comparing the short- and long-term effects of different techniques.

Pathophysiology of Fibrosis in the Vocal Fold: Current Research, Future Treatment Strategies, and Obstacles to Restoring Vocal Fold Pliability

Communication by voice depends on symmetrical vibrations within the vocal folds (VFs) and is indispensable for various occupations. VF scarring is one of the main reasons for permanent dysphonia and results from injury to the unique layered structure of the VFs. The increased collagen and decreased hyaluronic acid within VF scars lead to a loss of pliability of the VFs and significantly decreases their capacity to vibrate. As there is currently no definitive treatment for VF scarring, regenerative medicine and tissue engineering have become increasingly important research areas within otolaryngology. Several recent reviews have described the problem of VF scarring and various possible solutions, including tissue engineered cells and tissues, biomaterial implants, stem cells, growth factors, anti-inflammatory cytokines antifibrotic agents. Despite considerable research progress, these technical advances have not been established as routine clinical procedures. This review focuses on emerging techniques for restoring VF pliability using various approaches. We discuss our studies on interactions among adipose-derived stem/stromal cells, antifibrotic agents, and VF fibroblasts using an in vitro model. We also identify some obstacles to advances in research.

Treatment Outcomes of Angiolytic Laser-Assisted Glottoplasty in Patients With Sulcus Vocalis

Objective:

We have been performing glottoplasty using angiolytic laser, including pulsed dye laser (PDL) or potassium titanyl phosphate (KTP) laser, for the treatment of sulcus vocalis. In this study, we retrospectively reviewed the treatment results of sulcus vocalis patients who had undergone glottoplasty using angiolytic laser and evaluated the efficacy and safety of this surgical technique.

Methods:

From January 2008 to April 2016, 79 patients with sulcus vocalis who underwent angiolytic LASER-assisted glottoplasty were enrolled in the study.

Results:

Of the 79 patients who participated in this study, 55 were male, and 24 were female. PDL was used for glottoplasty in 68 patients, and KTP was used in the remaining 11 patients. Seventy-seven patients underwent surgery for bilateral vocal cord lesions, and only 2 patients underwent surgery for unilateral vocal cord lesion. After glottoplasty using angiolytic laser, most patients showed continuous improvement of the GRBAS (grade, roughness, breathiness, asthenia, strain) score and Voice Handicap Index score until 6 months after the operation. In addition, we observed improvement of objective voice indices such as noise to harmonic ratio, jitter, shimmer, and maximal phonation time postoperatively.

Conclusions:

Based on these results, we confirmed the efficacy and safety of glottoplasty using angiolytic laser in sulcus vocalis patients. Further studies are needed to confirm appropriate laser settings such as frequency of treatments and total energy delivered to the lesion. Also, multi-institutional studies are needed to confirm the efficacy and safety of the operation.

The Ability of Conditioned Media From Stem Cells to Repair Vocal Fold Injuries

OBJECTIVE

This study investigated the ability of hypoxia-induced 25-fold concentrated conditioned media (hCM) from human nasal inferior turbinate-derived mesenchymal stem cells (hTMSC) to repair injured vocal folds during the early phase of the wound-healing process.

METHODS

The vocal fold was injured in Sprague-Dawley rats. Next, hCM from hTMSC (the hCM group) or hTMSC (the hTMSC group) were injected into the injured vocal folds. As a control, saline (the phosphate-buffered saline group) or 25-fold concentrated media (the media group) was injected in the same manner. The vocal folds were harvested for quantitative real-time polymerase chain reaction (PCR) at 1 week and 2 weeks after injury. Histologic evaluation was performed at 3 weeks postinjury.

RESULTS

In the hCM group at 1 week after injury, PCR showed that the genes encoding hyaluronan synthase (HAS), HAS 1, and HAS 2 were significantly upregulated compared to the media and normal groups. The gene encoding procollagen III was significantly downregulated compared to the media group. Nearly identical results were obtained for the hTMSC group at 1 week after injury. Histological examination showed that the hCM group was similar to or better than the hTMSC group in collagen deposition and hyaluronic acid production.

CONCLUSION

The injection of hCM into injured vocal folds produced antifibrotic effects in the early phase of wound healing. These effects were equivalent to those produced by the injection of hTMSC. These results provide a foundation for the future clinical use of hCM for vocal fold regeneration.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:1867-1875, 2019.