ABSTRACT
OBJECTIVE: Vocal fold injection medialization (VFIM) is widely used as an initial treatment for unilateral vocal fold paralysis (UVFP). Current practices employ materials that share the limitation of temporary clinical effect from variable resorption rates. A novel silk protein microparticle-hyaluronic acid-based material (silk-HA) has demonstrated cellular infiltration and tissue deposition that may portend a durable medialization effect. We report on ≥12 months outcomes after VFIM with silk-HA. METHODS: Prospective open-label study of patients with UVFP that elected treatment with VFIM with silk-HA. Blinded experts rated laryngeal stroboscopic exams. RESULTS: Seventeen patients with UVFP underwent VFIM with silk-HA. Twelve of the 17 patients have ≥12 months follow-up. Seven patients demonstrated durable treatment benefit ≥12 months after injection with median improvement of 19 (p = 0.0156) in VHI-10. There was no significant change in VHI-10 between 1 and 12 months for these patients. Blinded ratings indicated that 5/7 patients with sustained improvements in VHI-10 exhibited complete or touch glottal closure at 12 months. Two of the seven patients exhibited a small (<1 mm) glottal gap at 12 months. Seven patients experienced initial benefit with later regression 3-4 months after injection. CONCLUSION: VFIM with silk-HA can offer durable improvement in voice-related outcomes for UVFP past 12 months. A subset of patients treated with silk-HA experienced early loss of effect around 3-4 months postinjection. Clinical factors predictive of sustained treatment response to silk-HA injection require further exploration. LEVEL OF EVIDENCE: 3 Laryngoscope, 2023.
ABSTRACT
Importance: The gold-standard treatment for laryngeal dystonia (LD) and essential tremor of the vocal tract (ETVT) is botulinum toxin (BoNT) chemodenervation. Although safe and effective, it is not curative, and periodic injections are required. Some medical insurance companies only cover injections at a 3-month interval, though some patients benefit from injections more frequently. Objective: To determine the proportion and characteristics of patients who receive BoNT chemodenervation treatment in intervals shorter than 90 days. Design, Setting, and Participants: This retrospective cohort study across 3 quaternary care neurolaryngology specialty practices in Washington and California recruited patients who underwent at least 4 consecutive laryngeal BoNT injections for LD and/or ETVT in the past 5 years. Data were collected from March through June 2022 and analyzed from June through December 2022. Exposure: Laryngeal BoNT treatment. Main Outcomes and Measures: Biodemographic and clinical variables, injection characteristics, evolution during the 3 interinjection intervals, and lifetime laryngeal BoNT treatment data were collected from patient medical records. Logistic regression was used to assess association to the short-interval outcome, defined as an average injection interval shorter than 90 days. Results: Of 255 patients included from the 3 institutions, 189 (74.1%) were female, and the mean (SD) age was 62.7 (14.3) years. The predominant diagnosis was adductor LD (n = 199 [78.0%]), followed by adductor dystonic voice tremor (n = 26 [10.2%]) and ETVT (n = 13 [5.1%]). Seventy patients (27.5%) received short-interval injections (<90 days). The short-interval group was younger than the long-interval group (≥90 days), with a mean (SD) age of 58.6 (15.5) years and 64.2 (13.5) years, respectively, and a mean difference of -5.7 years (95% CI, -9.6 to -1.8 years). There were no patient-related differences between the short- and long-interval groups in terms of sex, employment status, or diagnosis. Conclusions and Relevance: This cohort study demonstrated that while insurance companies often mandate a 3-month or greater interval for BoNT chemodenervation financial coverage, there is a considerable subset of patients with LD and ETVT who receive short-interval treatment to optimize their vocal function. Short-interval chemodenervation injections demonstrate a similar adverse effect profile and do not appear to predispose to resistance through antibody formation.
