Treatment of vocal fold immobility by glutaraldehyde-cross-linked collagen injection: long-term results.

Fifty-three cases of unilateral vocal fold immobility treated by glutaraldehyde-cross-linked (GAX) collagen over a 6-year period with a mean follow-up of 4.5 years were reviewed for assessment of the immediate and long-term effects on phonation. The mean amount injected was 1.47 mL. No long-term local or systemic reaction to the collagen was seen. The median preoperative maximum phonation time (MPT) was 7.5 seconds, the median immediate postoperative MPT 12 seconds, and the median long-term postoperative MPT 11 seconds. The median preoperative phonatory quotient (PQ) was 564 mL/s. The median immediate postoperative PQ was 320 mL/s, whereas the median long-term postoperative PQ was 385 mL/s. The quantitative improvement in the voice as measured by the PQ was thus 67% for the short range and 49% for the long range. The decline in the results over time was 20.3%. Vocal frequency analysis showed that the fundamental frequency and harmonics returned and were maintained in the long term for more than 80% of the patients with the help of speech therapy. This relative stability is explained by the findings of previous histological work. The fact that collagen, unlike Teflon, does not cause an inflammatory reaction and the partial maintenance of the improvement achieved, which is to be compared with the instability of the effects produced by resorbable substances, make it the "least objectionable" injectable for the treatment of unilateral glottic fold immobility. One must overcompensate 20% to 30%, given the results of the long-term stability studies