Transoral Endoscopic CO₂ Laser Surgery For Hypopharynx In Experimental Animals

Objective:Transoral CO2 laser surgery has demonstrated good results and. low morbidity in the treatment of selected laryngeal carcinomas, but experience in hypopharyngeal carcinomas is limited. To explore the substantial resection scope of CO2 laser surgery for hypopharynx and the course of wound healing in animals, we performed lateral sinus piriformis resection and posterior wall of the hypopharynx exsection using carbon dioxide laser under self-retaining laryngoscope on dogs, which pave the way for evaluating the clinic usefulness of transoral CO2 laser surgery in the treatment of selected hypopharyngeal carcinomas.Methods:Twenty-three dogs were randomized assigned to two groups,of whom 11 (group one) were performed lateral sinus piriformis resection, 12 (group two) were perfomed posterior wall of the hypopharynx exsection .6 dogs of group one were killed immediately or 4,8,12,16,20d respectively post-operation, and 7 dogs of group two were killed immediately or 7,14,21,28,35,42d respectively post-operation ,the whole larynx and hypopharynx were taken out and specimens were serially sectioned in order to observe the dimension of excision and the course of wound healing .The other 5 dogs of every group were fed until the wound healed, the duration were observed.Results:All the operations were successful and the results were satisfactory. In group one, thebleeding volume during operation is 80ml in one dog ,it took food the day post-operation;two dogs were bucking during eating and recovered after five days. In group two, thebleeding volume during operation is 70-90ml in three dogs, they took food the next daypost-operation, eight dogs were bucking during eating and recovered after ten days. Theexcision dimension was satisfactory. In group one with lateral sinus piriformis resection,the raw surface size was 7.5±0.8cm~2 and the healing time was 18.4±1.5d;In group two withposterior wall of the hypopharynx exsection, the wound surface was 7.0±0.5 c m2 and thehealing time was 39.8±1.9, the healing time in group two is significantly longer than that ofin group one.( t=19.535 p<0.01), there are no significance correlation between the woundsize and the healing time. We observed the post-operation healing process -cellulosemembrane coverage, granulation filling and epithelization. In group one,8 days later afteroperation, we can see mucosae defects, carbonization granules, inflammatory cellinfiltration ;16 days later, epithelium mucosae hyperblastosis was observed;20 days later,the wounds have been epithelizated. In group two, 7 days later after operation, we can seesporadic carbonization granules in the bottom and bilateralis of the wounds, mucosaedefects and inflammatory cell infiltration, 28 days later, fibrins in wounds were replaced bygranulation tissues gradually, we can observe epithelium regeneration, 42 days later, re-epithelialize covered the wounds and completed reparation process.Conclusion:Transoral CO2 laser was suitable for sinus piriformis and posterior wall of the hypopharynx resection. Animals can recuperate well with little complications. Although the course of wound healing was delayed, wound surface can recover with good laryngeal and deglutition functions. It was elucidated that the earlier hypopharyngeal carcinomas can be treated by transoral CO2 laser with sound laryngeal and deglutition functions.