Exploration Of In Vivo Visualization Of Experimental Endolymphatic Hydrops In Guinea Pigs With3.0Tesla MRI

Objective Establish experimental endolymphatic hydrops in guinea pigs withimmunization. Examination animal models of endolymphatic hydrops byauditory brainstem response,eletroeoehleogram, magnetic resonance imaging andhistologic morphometry was undertaken to investigate the correlation betweenmorphologic and functional changes in cochleas. In vivo visualization of experimentalendolymphatic hydrops in guinea pigs with3.0Tesla MRI the first time.Methods1.Twenty red eyes albino guinea pigs were randomly divided into twogroups.One group is control group(n=8),the other group is model group(n=12);andthey were operated on the left ears by extradural posterior cranial fossa approach toresult in endolymphatic hydrops with the method of immunization of KLH to theendolymphatic sac after systemic immunity(the control group animals were operatedthe same way and injected in the left endolymphatic sac with phosphate buffer). Theright ears remained as internal histologic controls.2. Auditory brainstem response, electrocoehleogram was tested with preoperativeanimals and postoperative one-week animals both control group and model group,assessing the ABR threshold value and-SP/AP value·3. After hearing tests, In vivo visualization of experimental endolymphatic hydrops inguinea pigs with3.0Tesla MRI by the Gd T1agent injection of tympanum.4. Histologic morphometry after the animals in two groups were killed was used toquantify hydrops by testing scala media area ratio.Results1.The results of hearing threshold of ABR revealed that the operated ears ofmodel group was higher than the preoperative results,There were significantdifferences(P<0.05).11of the12guinea pigs turned out to have high hearing thresholds(91.67%). But there were no significant differences before theintervention(P>0.05).2. The SP/AP ratios of electrocochleogram were significant differences betweenmodel group and control group after the intervention (P<0.05). Otherwise,there wereno significant differences before the intervention(P>0.05).3. The results of histologic morphometry revealed that the left ears of the model groupwith mild endolymphatic hydrops,especially in subapical and suprabasilar turn.However the results of the right ears of the model group and the ears of the controlgroup were negative.4. In vivo visualization of experimental endolymphatic hydrops in guinea pigs with3.0Tesla3D-FLAIR MRI(SIEMENS Verio,made in Germany) by the Gd T1agentinjection of tympanum. A negative imaging results were got.Conclusions1. The mature animal model of endolymphatic hydrops can be inducedby immunization with KLH through surgical intervention of the endolymphatic sac.2.The-SP/AP ratio of electrocochleogram can reveal early endolymphatic hydrops.3. The experimental animal model turn out to be mild endolymphatic hydrops,especially in subapical and suprabasilar turn.4.3.0Tesla3D-FLAIR MRI by the Gd T1agent injection of tympanum maybe wouldnot be enough to achieve in vivo visualization of experimental endolymphatichydrops in guinea pigs.