[The study of the enzyme histochemistry changes of thyroarytenoid when one side of RLN was excised].

OBJECTIVE

To chronologically evaluate the changes in both sides of thyroarytenoid (TA) muscles. when one side of recurrent laryngeal nerve (RLN) was cut off.

METHOD: In 7 adult mongrel dogs, 2 dogs for control and the other 5 dogs for the following experiment: a 2 cm segment of right RLN was excised under intraperitoneal sedation. The animals were killed at 2, 4, 6, 8, 10 week respectively and the thyroarytenoid were processed for histochemical reaction and electromicroscope. The mean muscle fiber, standard deviation and muscle fiber type composition were determined.

RESULT: For the injured sides, denervation resulted in shrinking of all the fibers at four weeks. At ten weeks, however, all the muscles were fibrosed. For the uninjured sides (left side), TA diameter appeared compensatory changes at four weeks, this changes were obvious at ten weeks. Variability of the fiber composition was observed throughout the study; however, there was no specific trend in changes before ten weeks.

CONCLUSION

When the RLN was excised, the fibers in the uninjured side of thyroarytenoid appeared compensatory changes in fiber diameter, which could give rise to the recovery of the laryngeal function.