Objectives: To evaluate the long-term (24 months) clinical performance (vocal fold function) and safety of hylan B gel as compared with bovine cross-linked collagen in the treatment of patients with glottal insufficiency.
Material and methods: In a prospective trial, 70 patients with glottal insufficiency due to unilateral vocal fold paresis (n =35) or atrophy (n =35) were randomized to received either hylan B gel (n =47) or collagen (n =23) injections into 1 vocal fold. Forty-two of the patients were examined 24 months after treatment. Evaluations were made based on patients' subjective ratings, digitized videostroboscopic measurements, maximum phonation time and phonation quotient.
Results: The patients' self-ratings were significantly improved in both the hylan B gel and collagen groups. Videostroboscopic measurements of glottal closure were significantly improved for both groups. The hylan B gel group showed a trend towards less resorption at the injected vocal fold edge in comparison with the collagen group (p =0.05). No serious adverse events were observed. Twenty-eight patients dropped out of the study after 12 months: 18 had been re-injected or operated on with medialization laryngoplasty due to insufficient voice and 10 had either died of causes unrelated to the study or refused to attend follow-up.
Conclusions: No long-term side-effects were found for either the hylan B gel or collagen groups after injection treatment. Both treatments resulted in significantly improved voice as rated by the patients and significantly improved glottal closure. Some resorption was noted for both substances, and approximately 25%, of the patients chose re-treatment 2 years after the initial treatment.