Comparison of Transtympanic and Extratympanic Electrocochleography

Electrocochleography (ECoG) has been an important tool in the diagnosis of Meniere’s disease or endolymphatic hydrops. There are two methods employed, transtympanic and extratympanic. Many have regarded the results of these methods as being equally reliable. The purpose of this study is to determine any differences in sensitivity between the two methods. In this study patients with known endolymphatic hydrops or Meniere’s disease underwent ECoG testing with both the extratympanic method and the transtympanic method on the same day in the same ear. The results show a significant difference between the two methods, with the transtympanic wave values being smaller and therefore more sensitive than the extratympanic method. In addition, transtympanic ECoG resulted in better waveform morphology and better correlation with the audiometric findings in endolymphatic hydrops and Meniere’s disease. The results emphasize the superior role of transtympanic ECoG over extratympanic ECoG as a valuable component in the confirmation of Meniere’s disease or endolymphatic hydrops along with history and audiometric findings characteristic of the disease. Implications of the study promote the use of transtympanic ECoG rather than extratympanic ECoG in patients with symptoms suggestive of Meniere’s disease or endolymphatic hydrops.

Endoscopic transtympanic Eustachian tube dilatation: An overview of evaluation methods and dilatation technique

Endoscopic technique in patients undergoing chronic ear surgery allows visualization of protympanic(proximal)segment of the Eustachian tube(ET).The proximal cartilaginous ET is a common site of anatomical Obstruction in chronic otitis media and it is this proximal end of ET that is being observed,instrumented and dilated with transtympanic methods.The aim of this article is to discuss our approach to the assessment of the Eustachian tube using opening pressure measurement,endoscopic assessment of the protympanic segment of ET and Valsalva CT.And also to discuss detailed technique of transtympanic Eustachian tube dilatation.

Radiologic anatomy of the round window relevant to cochlear implantation and inner ear drug delivery

Objective:To determine anatomic relationships and variation of the round window membrane to bony surgical landmarks on computed tomography.Study design:Retrospective imaging review.Methods:100 temporal bone images were evaluated.Direct measurements were obtained for membrane position.Vector distances and angulation from umbo and bony annulus were calculated from image viewer software coordinates.Results:The angle of round window membrane at junction with cochlear basal turn was(42.1±8.6)°.The membrane’s position relative to plane of the facial nerve through facial recess was(14.7±5.2)°posterior from a reference line drawn through facial recess to carotid canal.Regarding transtympanic drug delivery,the round window membrane was directed 4.1 mm superiorly from the inferior annulus and 5.4 mm anteriorly from the posterior annulus.The round window membrane on average was angled superiorly from the inferior annulus(77.1±27.9)°and slightly anteriorly from the posterior annulus(19.1±11.1°).The mean distance of round window membrane from umbo was 4 mm and posteriorly rotated 30°clockwise from a perpendicular drawn from umbo to inferior annulus towards posterior annulus.Together,these measurements approximate the round window membrane in the tympanic membrane’s posteroinferior quadrant.Conclusions:These radiologic measurements demonstrate normal variations seen in round window anatomy relative to facial recess approach and bony tympanic annulus,providing a baseline to assess round window insertion for cochlear implantation and outlines anatomic factors affecting transtympanic drug delivery.