Current approaches to management of vocal fold scar

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.

5-Aminolevulinic Acid-Mediated Photodynamic Therapy Improves Vocal Fold Wound Healing in Rats

OBJECTIVE

Studies showed that photodynamic therapy (PDT) might be able to prevent vocal fold scar formation when treating laryngeal lesions. We aim to investigate if PDT improves vocal wound healing and reduces scar formation in both prophylactic and remodeling procedures performed in vivo.

STUDY DESIGN

In vivo.

METHODS

Vocal fold stripping was performed in Sprague-Dawley rats. PDT was performed with intraperitoneal injection of 100 mg/kg 5-Aminolevulinic Acid (5-ALA) and 635 nm laser irradiation of 20, 40, and 60 J/cm² . PDT was performed immediately after surgery to study the prophylactic effect and 4 weeks after surgery to study the remodeling effect. Gene expression was evaluated with real-time PCR at 1 week after PDT. Histologic evaluations were performed 12 weeks after PDT, including hematoxylin-eosin, Masson, Alcian blue staining, and immunohistochemical staining of collagen I and III.

RESULTS

PDT induced similar effects on the vocal fold wound healing outcomes in both prophylactic and remodeling procedures. Expression of MMP8, MMP13, HAS2, and TGFβ1 was significantly elevated. Histologic evaluation revealed significantly increased thickness, decreased density of collagen, and increased deposition of hyaluronic acid in the lamina propria. Immunohistochemistry also revealed better distribution and reduced density of collagen I and III. The most obvious changes were seen in the 60 J/cm² PDT group.

CONCLUSION

PDT could significantly improve vocal wound healing by providing both prophylactic effects and remodeling effects. It may be a minimally invasive treatment for vocal fold lesions with slight vocal scarring, and may be used to treat acute or chronic vocal injury to reduce vocal scarring.

LEVEL OF EVIDENCE

N/A Laryngoscope, 133:1943-1951, 2023.

In vitro evaluation of genipin-crosslinked gelatin hydrogels for vocal fold injection

Glottic insufficiency is one of the voice disorders affecting all demographics. Due to the incomplete closure of the vocal fold, there is a risk of aspiration and ineffective phonation. Current treatments for glottic insufficiency include nerve repair, reinnervation, implantation and injection laryngoplasty. Injection laryngoplasty is favored among these techniques due to its cost-effectiveness and efficiency. However, research into developing an effective injectable for the treatment of glottic insufficiency is currently lacking. Therefore, this study aims to develop an injectable gelatin (G) hydrogel crosslinked with either 1-ethyl-3-(3-dimethylaminpropyl)carbodiimide hydrochloride) (EDC) or genipin (gn). The gelation time, biodegradability and swelling ratio of hydrogels with varying concentrations of gelatin (6-10% G) and genipin (0.1-0.5% gn) were investigated. Some selected formulations were proceeded with rheology, pore size, chemical analysis and in vitro cellular activity of Wharton's Jelly Mesenchymal Stem Cells (WJMSCs), to determine the safety application of the selected hydrogels, for future cell delivery prospect. 6G 0.4gn and 8G 0.4gn were the only hydrogel groups capable of achieving complete gelation within 20 min, exhibiting an elastic modulus between 2 and 10 kPa and a pore size between 100 and 400 μm. Moreover, these hydrogels were biodegradable and biocompatible with WJMSCs, as > 70% viability were observed after 7 days of in vitro culture. Our results suggested 6G 0.4gn and 8G 0.4gn hydrogels as potential cell encapsulation injectates. In light of these findings, future research should focus on characterizing their encapsulation efficiency and exploring the possibility of using these hydrogels as a drug delivery system for vocal fold treatment.

Cryotherapy Modifies Extracellular Matrix Expression of Vocal Fold in Rat Models

OBJECTIVES

Vocal fold (VF) scarring is the major cause of voice disorders. Cryotherapy is an effective anti-scarring therapy for skin lesions. The aim of this study was to explore the anti-scarring potential of cryotherapy in vocal folds.

METHODS

The extracellular matrix (ECM) mRNA expression of cryotherapy on normal VF tissue and the histologic results of cryotherapy on vocal fold healing were studied. Fifteen rats were introduced cryotherapy on the normal VF bilaterally and were harvested for real-time polymerase chain reaction (RT-PCR) analysis for collagen I, collagen III, TGFβ1, decorin, fibronectin and HAS1 at 1 day, 3 days and 7 days. Ten rats were unilaterally injured by stripping lamina propria and immediately treated with or without cryotherapy and were harvested at 2 months for histological and immunohistochemical analysis.

RESULTS

Regenerative effect of cryotherapy was validated of ECM gene expression. Histological and immunohistochemical analysis showed significantly increased hyaluronan, decreased collagen, and increased decorin deposition in injury-cryotherapy cohort compared with injury control cohort and normal control cohort.

CONCLUSIONS

Cryotherapy may provide an optimal environment for vocal fold tissue regeneration. The results of the present investigation suggest that cryotherapy has therapeutic potential in prevention and treatment of vocal fold scarring.