Empirical Study For The Prevention And Treatment Of Middle-ear Adhesion With Obstructive Materials Implantation

ObjectiveMiddle ear adhesion refers to the hyperplasy of middle ear fibrous tissue and cicatricial tissue which caused by a variety of reasons,that forms fibrous connective tissue adhesion,prevents tympanic membrane and ossicular movement,causes middle ear dysfunction and conductive hearing loss,and results in conductive deafness.There is no effective measures for long-term treatment in clinic,once middle ear adhesions or fibrosis developed,drug is ineffective and surgical release required,but then after,another new adhesions often come into being again. Therefore,the prevention and treatment of middle ear adhesions and post-operative adhesions have important clinical significance.Absorbable polymer materials are used broadly in clinic currently.It is reported that absorbable medical film is effectiv,it can protect surgical wounds and prevent adhesion,and applied broadly in abdominal surgery,pelvic surgery and orthopedic surgery,but report is less in the ear surgery.In this study,we will investigate the preventive effect of middle ear adhesion by implanting absorbable medical film(NANKE) and other obstructive materials in guinea pig promontorium tympani after clogging the eustachian tube,and will provide a theoretical basis for absorbable medical film in clinical applications. Methods1.36 guinea pigs with normal hearing and no ear disease were used in this study, acoustic immitance and ABR testing would carry on in pre-operation to evaluate their eustachian tube and middle ear function and ABR thresholds.2.Using ear-back approach to get into the middle ear of guinea pig and identify interior anatomical structure,clog tympanic segment of eustachian tube -- Eustachian tube cracks,implant absorbable medical film(NANKE) and other obstructive materials in guinea pig promontorium tympani.3.The animals were divided into three groups,Separately implanting with NANKE(group 1),silicone plastic(group 2) and nothing(group 3).Animals in each group were sacrificed 15 and 90 days respectively,so as to observe its changes in audiology and pathomorphology.Results1.The tympanograms obtained were all Type A for normal guinea pigs in pre-operation,and the results show significant differences in the equivalent canal volumes between male and female guinea pig(t=2.599,P=0.012).2.It was possible in all cases to visualize the majority of structures of the tympanic cavity:promontory,hammer-stake complex,incudostapedial joint,stapes, round window,semicircular canal and so on.In particular,the huge cochlea hangs in the center of otocyst,which locates horizontal and inclines down a bit in the front,and tympanic segment of eustachian tube - eustachian tube cracks hiding in the top of cochlear.3.In 15 days,the ABR thresholds of study group(group 1,group 2) and control group(group 3) increased evidently and had significant differences with normal ones (P=0.000),and significant differences also existing in Group 1 and Group 2 compared with group 3(P=0.004,P=0.025),no difference between Group 1 and Group 2 (P=0.389).In 90 days,the ABR thresholds compared with normal ones also had significant differences(P=0.000),but significant differences existing in Group 1 compared with Group 2 and group 3(P=0.03,P=0.002),and no difference between Group 2 and group 3(P=0.232).To compare in 15 days and 90 days,Group 2 and group 3 had significant difference(P=0.03,P=0.045),but no difference was found in Group 1(P=0.205).4.Histopathology showed:Promontory mucosa of control ears is cube or squamous epithelium,subcutaneous tissue is loose and full of vein,no inflammatory cell infiltrate or vein changes were found.15 days after operation,as to Group 1(NANKE) and Group 2(silicone plastic),the promontory mucosa was enlarged due to vascular dilatation,vascular proliferation,small amount of inflammatory cell infiltrate,edema and hyperplasia of the lamina propria.But in group 3,this symptom is more Sever.90 days after operation,in Group 1,a little undecomposed NANKE material was found,it is surrounded by granulation tissue,a bit inflammatory cell infiltrate and necrosis.But it still has obviouse lacouna all around and adhesion is not evident,in Group 2(silicone plastic),a lot granulation tissue and fibrous connective tissue can be seen,and group 3,middle ear and internal ear have a lot necrosis.Conclusions1.Acoustic immitance test can show a good middle ear function of guinea pig,its tympanogram various index of the normal range of acoustic tests in guinea pigs will provide a normal reference value standard,and different genders should refer to different normal standard because of the significant differences in the equivalent canal volumes between male and female.2.The ear-back approach to the guinea pig middle ear is a rapid,simple and small wound technique that makes the guinea pig the animal of choice for many otologic investigations.3.The ABR thresholds will be increased than normal whether obstructive materials implanted or not after the eustachian tube clogged off,and it gets higher as time goes by.4.Earlier period,the NANKE and silicone plastic can decrease guinea pig's change of threshold,and the inflammation and vascular reactivity are lighter than the control group of promontory mucosa. 5.Later stage,the NANKE is able to decrease the change of guinea pig's threshold,but for silicone plastic,this function is not obviouse.Also,the histopathological changes is lighter than silicone plastic and control group.6.NANKE has nice biocompatibility,and can prevent and cure middle ear adhesion effectively.