Influence Of The Preservation Of Middle Ear Mucosa Around Eustachian Tube Opening In The Recovery Of Mucociliary Transport Function On Post-Tympanoplasty

BACKGROUND:Chronic suppurative otitis media is mainly a chronic inflammation of the middle ear and mastoid cavity,characterized by persisted tympanic membrane perforation.It is one of the most common childhood diseases in developing countries.Most of the patients can be cured,but there are still some patients recurrently attacked,causing sensorineural hearing loss or tympanosclerosis.There are probably 65 to 330 million people worldwide suffered from the disease,becoming a significant burden of disease and economy around the word.Bacterial infection is a known risk factor for chronic suppurative otitis media,but antibiotic treatment often failed.In addition,recurrent inflammatory stimulation affects cell regeneration,so that perforated tympanic membrane is hard to heal itself.Finally,surgery such as tympanoplasty is still needed to repair tympanic membrane perforation and establish a barrier to prevent bacteria from infecting the middle ear mucosa and the completion of sound conduction.From our clinical experience,we have found that patients with post-traumatic tympanic perforation have a shorter recovery time and better curative effect than patients with post-otitis media perforation after reconstructing attic and tympanoplasty,which may be correlated to the middle ear mucosa or Eustachian tube fuction.At the same time,it has been reported that the success rate and prognosis of tympanoplasty are directly related not only to the function of the eustachian tube,but also to the function of the mucosa surrounding the Eustachian tube opening.The mucosa epithelium of the Eustachian tube and its tympanic ostium is composed of pseudostratified ciliated columnar cells,primarily undertake function of mucus transport.What’s more,it has found a close correlation between the mucosa around the Eustachian tube opening and the ventilation of the middle ear cavity.Once the mucosa appears swelling or granulation tissue forms,which blocks the Eustachian tube opening and hampers the tympanic mucus transport.If mucociliary clearance appears disfunction in tympanoplasty,it will result in failure of the clearance of absorbable gelatine sponge in tympanic cavity.However,long-term residue of gelatine sponge may lead to mucosal inflammation,fibrosis and auditory ossicular chain disfunction.AIM:Analyze the influence of the mucosa around the Eustachian tube opening on the prognosis in tympanoplasty.METHOD:1、We discovered the middle ear anatomy of New Zealand rabbits by transcanal endoscopy and completed basic training of tympanoplasty in rabbits’bullae,which laid the foundation for the following research.2、Staining in the mucosa around the Eustachian tube and the middle ear mucosa away from the Eustachian tube with indigo carmine dye,we visualised the dye’s routes in the middle ear of 12 rabbits by endoscopic examination to verify that the mechanism of mucociliary clearance in the middle ear and the foundation of the Eustachian tube keep good condition.And then,we removed partial mucosal around the tympanic ostium of Eustachian tube and filled the bullae with levofloxacin gelatin spooge.In addition,all the New Zealand rabbits were divided into two groups randomly,and rabbits in Group Al were sacrified after 12 weeks but rabbits in Group A2 were sacrified 24 weeks later.3、Last,we completed macroscopic observation in the difference of residual gelfoam spooge in the bullae between rabbits in Group A1 and Group A2.And then,Hematoxylin-eosin staining,scanning electron microscopic examination were carried out in regenerated mucosa in damaged area of the middle ear,in order to analyze the difference of regenerated mucosa between Group Al and Group A2.RESULTS:1、The middle ear structures of New Zealand rabbits are similar to that of human and the New Zealand rabbits is superior to the three-dimensional anatomical model as a anatomic training model of tympanoplasty with a tympanoscope.2、The secretions in the middle ear cavity are cleared from the Eustachian tube to the nasopharynx,but we only observe one main ciliary pathway.3、When the mucosa around the Eustachian tube opening is damaged,the removal of gelfoam spooge delay.And the recovery of regenerated mucosa delay and there are no ciliary bundles in the epithelial layer of the regenerated mucosa.CONCLUSION:The middle ear anatomy of New Zealand rabbit is akin to that of human,so the New Zealand rabbits can be used as the anatomical training model of tympanoplasty for the junior otologists.And the Eustachian tube is the main pathway of mucociliary transport in the middle ear.Not only the damaged mucosa around the tympanic ostium delayed the revomal rate of gelfoam spooge in the bullae,but also regenerated mucosa,whose epithelial layer still didn’t ciliated cells 24 weeks later,was different to normal mucosa in the middle ear.What’s more,the research reveals that the mucosa around the Eustachian tube opening in the middle ear is correlated with the recovery of tympanoplasty and provides a certain researching basis for protection of the mucosa around the Eustachian tube opening in the middle ear surgery.