Effect of a Single Injection of Basic Fibroblast Growth Factor into the Vocal Folds: A 36-Month Clinical Study

Abstract

Objective: A single injection of basic fibroblast growth factor (bFGF) into the vocal folds of patients with glottal insufficiency has been shown to be effective for a few years. However, the long-term therapeutic effect of a single injection of bFGF into the vocal folds has yet to be demonstrated. In this study, the therapeutic effect of a single injection of bFGF into the vocal folds was investigated over several years by monitoring patients for 36 months following this treatment.

Methods: Nineteen patients with glottal insufficiency received injections of bFGF diluted to 20 μg/mL in the superficial layer of the lamina propria of the bilateral vocal folds. The following parameters were evaluated at preinjection baseline and 6, 12, 18, 24, and 36 months later, and statistical comparisons were performed. The parameters evaluated were: the Grade, Rough, Breathy, Asthenic, and Strained (GRBAS) scale score; maximum phonation time; acoustic analysis; and glottal wave analysis (GWA) and kymograph edge analysis (KEA) using high-speed digital imaging (HSDI). The amplitude perturbation quotient (APQ) and period perturbation quotient (PPQ) were measured by acoustic analysis. The mean minimum glottal area during vocalization and mean minimum distance between the vocal folds were measured by GWA. The amplitudes of the bilateral vocal folds were measured by KEA.

Results: Postinjection, the GRBAS scale score decreased from 6 months after injection, and maximum phonation time was prolonged. The mean minimum glottal area during vocalization and the mean minimum distance between the vocal folds calculated by GWA of HSDI decreased significantly after 6 months. These effects persisted until 36 months postinjection. APQ and PPQ derived from acoustic analysis tended to decrease, but not significantly. There was no clear change in the amplitudes of the bilateral vocal folds calculated by KEA of HSDI before and after injection.

Conclusions: These results suggest that the effects of a single injection of bFGF into the vocal folds persist for 36 months.

Keywords: Basic fibroblast growth factor; Glottal insufficiency; High-speed digital imaging; Vocal cord injection.