Treatment of vocal fold immobility by injectable homologous collagen: short-term results

Various implant materials have been used to treat glottic insufficiency by means of intracordal injection. So far, autologous fat is the most commonly used. Homologous collagen is a new injectable acellular graft material. This collagen, made of 200-μ particles, is delivered as a freeze-dried powder in a 1-cc-unit syringe and is rehydrated with standard saline solution prior to injection. A prospective study was conducted on 23 patients with unilateral vocal fold paralysis. All injections were performed under general anesthesia using the collagen injection system and a 25-gauge needle. A mean quantity of 1.05 ml (SD: 0.41) of collagen was injected as much as possible in the deep part of the lamina propria. Voicing was resumed after 2 days. The mean follow-up was of 8 months (range: 2–18). Functional results were measured according to the ELS protocol. G(rade), R(oughness) and B(reathiness) according to Hirano were reported on a four-point grading scale showing an improvement from 2.13 to 1.13 for G (P<0.001), from 1.50 to 0.82 for R (P<0.002) and from 1.73 to 1.05 for B (P<0.001). The parameters selected for videolaryngostroboscopy, G(lottal) (Clo)sure, (R)egularity, (M)ucosal (W)ave and (Sym)metry, were measured on a visual analog scale. They showed an improvement from 23 to 19 for Clo (P=0.087), from 15 to 6 for R (P=0.001), from 15 to 11 for MW (P=0.039) and from 17 to 8 for Sym (P=0.001). For the aerodynamic parameters, the maximum phonation time (MPT) and the phonation quotient (PQ) showed an improvement from 5.8 to 8.9 s (P=0.002) and from 704.5 to 449.7 ml/s (P=0.004), respectively. The acoustic parameters were improved from 5.3 to 3.6 (P=0.045) for the jitter (%), they didn’t change for the shimmer [(%): 2.4], and they were improved non-significantly from 187.9 to 218.7 Hg for the frequency range. The lowest level intensity was non-significantly increased from 49.6 to 51.3 dB. Regarding the subjective evaluation, the Voice Handicap Index (VHI) was improved from 65 to 37. To date, no homologous collagen-related morbidity has been observed. Injectable homologous collagen appears to be safe and suitable for injection laryngoplasty. Long-term results are pending.