Vibratory capacity and voice outcome in patients with scarred vocal folds treated with collagen injections--case studies.

This prospective case study evaluates the effect of collagen injections on vibratory capacity and voice outcome in four patients with vocal fold scarring. The minimum follow-up time was 6 months. We studied the effect of the injections on the vibratory capacity in a multidimensional way, using computerized image analysis of videostroboscopy, acoustic and perceptual analysis of voice recordings, as well as patients' self-evaluations. Subjective voice ratings from the patients showed improvement in two patients, while two patients had no change in voice function. None of the patients experienced any side effects from the treatment. The documented acoustic and perceptual changes were marginal, but the videostroboscopic findings suggest some improvement in vibratory capacity.