Background: Comprehensive evaluation of voice function is the precondition for indication and quality control of every phonosurgical procedure. In 53 patients presenting with glottic insufficiencies of different etiologies an external vocal fold medialisation was performed. Functional voice results obtained with this operation are presented and discussed. Methods: The following voice parameters were measured preoperatively and postoperatively, and statistical comparison was performed: mean fundamental frequency and sound pressure level, frequency and intensity range (voice range profile), perceptual evaluation of hoarseness, and maximum phonation time. The impairment of vocal communication skills was rated on a newly developed 7-point scale. A combined parameter called "Voice Dysfunction Index" was introduced for global assessment of vocal abilities in particular for long term observations. Results: Statistically significant improvement of all voice parameters was demonstrated. Interestingly, in nearly all measurements male patients yielded significantly better results than females. Glottic insufficiencies due to scarring produced poorer functional results but without statistical significance. A statistically significant correlation between the preoperative and postoperative Voice Dysfunction Index could be observed. This score was also significantly correlated with the degree of glottal gap. No significant correlation between voice results and preoperative delay or follow-up period were observed. Voice therapy was performed in 81% of the patients. Correlation of duration of voice therapy and voice results was statistically significant and negative. Analysis of this surprising result showed that it was caused by some patients with vocal fold scarring in whom outcome was poor despite a long period of voice therapy. Conclusions: Significant improvement of vocal function can be obtained by external vocal fold medialization in patients with glottic insufficiencies. Glottal gaps caused by vocal fold scarring and/or atrophy can be treated with this method, too. However, results are not as good as in paralysis and require additional long term voice therapy. Satisfying results can be expected in patients with a long history of disturbances, and in older patients. Due to the reversibility of the operation, external vocal fold medialization can be performed even in cases of palsy prior to the spontaneous recovery period. The degree of glottic gap determines the functional disturbance. The degree of the preoperative impairment correlates with the outcome. Results are stable with respect to the follow-up period (mean 66 weeks).
