Abstract
Since 1971, an improved technique of glottic reconstruction following extended frontolateral partial laryngectomy has been used in our clinic; a bulge is constructed at the level of the vocal cord with a superiorly based sternohyoid muscle flap, which is covered by either a rotating hypopharyngeal mucosa or a free graft from the oral mucosa. Clinically, postoperative phonation has usually been satisfactory. The purpose of the present study was to investigate macroscopic and microscopic changes in the newly constructed bulge. The surgery was carried out on 30 mongrel dogs divided into three groups: (1) The nerve supplies appeared in the operative field were preserved and the muscle flap was covered with a rotating pharyngeal flap.(2) The nerve supplies were eliminated and the muscle flap was covered with a pharyngealflap, and (3) The nerve supplies were preserved and the muscle flap was covered with a free graft from the oral mucosa.
The results obtain ed are as follows:
I. Macroscopic findings.
1) The size of th e bulge did not depend on the groups as described above.
2) In most cases the top of the bulge was located at the same level as that of the unoperated vocal cord or slightly lower.
3) The medial edge of the bulge was more frequently uneven in the cases in which a rotating flap was used than in the cases in which a free graft was used.
4) There was no necrosis in the mucosa of the bulge or adhesion at the anterior commissure in any case.
II. Microscopic findings.
1) The epithelium of the mucosa of the bulge were thicker than that of the normal vocal cord in many cases regardless of its original places.
2) The epithelial retridge of normal oral and hypopharyngeal mucosa became flat after the surgery in almost all the cases.
3) The lamina propria of the mucosa of the bulge were thinner than that of the normal vocal cord, especially it was very thin in the cases of free graft.
4) The elastic fibers were seldom observed in the lamina propria of the mucosa of the bulge, whereas the collagenous fibers were found more densely than in the normal vocal cord. Especially, in the cases of free graft of the oral mucosa, the lamina propria was extremely thin.
5) Degeneration and atrophy were found more or less in the muscle flap in all the cases regardless of preservation of the nerve.
