[Long-term outcomes of lateral vocal fold autologous fat injection for unilateral vocal fold paralysis]

Objective: To investigate the long-term outcomes of patients with unilateral vocal fold paralysis resulting in dysphonia treated with lateral vocal fold autologous fat injection. To analyze the factors that may affect the long-term efficacy of the procedure. Methods: From July 2003 to June 2020, 163 patients (86 males and 77 females), aged 9-73 years (mean (34.50±12.94) years) with unilateral vocal fold paralysis resulting in dysphonia underwent transoral laryngoscopic injection of autologous fat into the lateral vocal folds. Subjective auditory perception assessment (GRBAS scale), objective acoustic assessment, voice handicap index (VHI) evaluation and stroboscopic laryngoscopy were compared before and after the surgery. Patients were followed up for 1 to 18 years, with median follow-up time of 6 years. SPSS 22.0 software was used for statistical analysis. Results: Of 163 patients, 17 patients (10.4%) had mild hoarseness (G1) and 146 patients (89.6%) had moderate to severe hoarseness (G2-3). Stroboscopic laryngoscopy revealed an arch-shaped vocal fold on the affected side, fixed in the paramedian position or abduction position, with obvious glottic closure fissure. Postoperatively, voice recovered to normal (G0) in 139 patients (85.3%), mild hoarseness (G1) in 18 patients (11.0%) and moderate hoarseness (G2) in 6 patients (3.7%). Of these, 131 patients (80.4%) showed significant improvement in hoarseness, 29 patients (17.8%) showed mild improvement and 3 patients (1.8%) showed no significant improvement in hoarseness. Objective acoustic parameters of Jitter, Shimmer, NHR and MPT improved significantly, as did VHI scores. Stroboscopic laryngoscopy showed medialization of the affected vocal folds, improved vocal fold closure and normal or nearly normal vocal fold mucosal waves. With a fat injection volume of 3.0-4.5 ml, the patient's subjective auditory perception scores of G, R, B and A improved more significantly within 3 months after surgery, and both VHI and MPT were significantly better since 1 year after surgery. With bilateral vocal fold injection, the B and A scores improved significantly from 1 month postoperatively compared to unilateral injections(unilateral vs. bilateral injection 1 month post-operation, t_{B scores}=1.42,t_{A scores}=1.51,P<0.05). Conclusions: The long-term efficacy of autologous fat injection in the paraglottic space for the treatment of unilateral vocal fold paralysis was stable. The efficacy of the surgery was related to the amount of fat injected, unilateral or bilateral of the injection.