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Laryngeal Electromyography-Guided Hyaluronic Acid Vocal Fold Injection for Unilateral Vocal Fold Paralysis—Preliminary Results

Conclusion
LEMG-guided HA VFI provides UVFP patients with neuromuscular function evaluation and treatment in one step. This clinical technique is feasible, and the short-term results are satisfactory.

from the Journal of Voice

Implantation of Esterified Hyaluronic Acid in Microdissected Reinke’s Space After Vocal Fold Microsurgery: Short- and Long-Term Results

In this study are reported the laryngeal and vocal results obtained after a microflap excision of benign vocal fold (VF) lesions and immediate implantation of esterified hyaluronic acid (EHA) in the surgical wound. In a previous pilot study on 11 cases, we have shown an excellent tolerance of this bioimplant. The objectives are to confirm the innocuity of the technique, to demonstrate the laryngeal and vocal evolution at short and long term, and to evaluate the eventual positive impact of EHA implantation on the pliability of the superficial layer of the lamina propria (SLLP) and on voice. This is a prospective and comparative study on 83 patients suffering from various benign VF lesions. Thirty-three patients were implanted with EHA, whereas 50 patients did not undergo implantation at the end of the microsurgical procedure.All patients undergo rigid laryngoscopy and microflap excision procedure under general anesthesia. After freeing up of the Reinke’s space and creation of a mucosal microflap, a few fibers of EHA are inserted in the surgical wound, before closure of the incision with fibrin glue. Serial laryngeal and vocal assessments are performed in all patients using videostroboscopy (Wolff and Xion), perceptual and objective voice evaluation (MDVP software, Kay Elemetrics), and phonatory function measurements (Aerophone II). Pre- and early postoperative means are compared by analysis of variance. Delayed and long-term evolution of laryngeal and vocal data are compared by means of nonparametric statistical methods. The longest follow-up in the implanted group is 4 years. Early postoperative results are similar in both groups: a significant improvement of a majority of laryngeal and vocal data is observed after microsurgery. In the long term, the two groups exhibit a different behavior: further improvement of voice, as an ongoing process, is only observed in the EHA implanted group, together with improvement of some videostroboscopic characteristics. The nonimplanted group remains stable, with no further improvement of the voice quality obtained after microsurgery. Excellent short- and long-term tolerance of EHA implantation is confirmed by this larger series. The use of EHA implant in microdissected SLLP is safe and leads to good laryngeal and vocal outcomes in the treated patients. More interestingly, treated cases exhibit a continuous improvement over a long period of time.

from the Journal of Voice

Does Hyaluronic Acid Distribution in the Larynx Relate to the Newborn’s Capacity for Crying?

from Laryngoscope

Abstract:
Objectives/Hypothesis: The newborn is heavily dependent on voice communication and therefore has relatively higher vocal demands and expenditures than the adult, the loudness output per mass performance exceeds that of the adult, and the newborn larynx exhibits significant histological and biochemical differences. The neonatal larynx is capable of sustaining relatively greater pitch and loudness than the adult over longer periods of time. This ability may be related to a more compact arrangement of collagen within the lamina propria, less interstitial space, and a uniform distribution of hyaluronic acid (HA). As HA is the primary determinant of vocal fold viscosity and water content, the distribution of HA in the superficial portion of the neonatal vocal fold is hypothesized to be related to newborn crying endurance. Our objective was to examine the histological structure and the quantity and arrangement of HA within the lamina propria of the pediatric larynx and review the relevant physiology of hyaluronic acid and its impact on voice production.

Study Design: Histological and digital subtraction analysis.

Methods: Intact, neonatal larynges were sourced from fresh cadaveric specimens. Trichrome stain was used to assess the collagen content and location in the tissues. HA was stained using a colloidal iron staining technique with and without incubation with bovine testicular hyaluronidase. Average optical density was calculated in tissue before and after treatment with hyaluronidase, and the stain intensity ratio was calculated.

Results: A total of 14 larynges were suitable for examination, eight males and six females. Histological examination revealed a uniform appearance of the vocalfold without evidence of a distinct vocal ligament or layered structure. Colloidal iron staining revealed an even distribution of HA throughout the vocal fold with no significant difference between quadrants. Images of the colloidal iron-stained tissue had a mean pixel intensity of 82 of 255. Slides of vocal fold tissue treated with hyaluronidase revealed a pixel intensity of 106 of 255 for a 22% mean difference in stain intensity (P < .01).

Conclusions: The identification of the layered structure of the adult lamina propria has raised a number of questions as to the development and purpose of the human larynx. Based on histological observations from the current study, possible explanations for the physiological differences include differences in the distribution and tissue concentration of HA and consequently dynamic viscosity, oncotic affinity for water, and less intercellular space in the superficial lamina propria.