Does intratympanic gadolinium injection predict efficacy of gentamicin partial chemolabyrinthectomy in Menière's disease patients?

Abstract

Using actual diagnostic criteria, the diagnosis of certain Menière's disease remains impossible during life without histopathologic confirmation. Assessing the value of a diagnostic test is difficult due to the lack of a gold standard. Recent studies reported on the use of MRI after intratympanic gadolinium injection to demonstrate endolymphatic hydrops in vivo. We evaluate whether MRI after intratympanic gadolinium administration is useful for predicting the effect and outcome of intratympanic gentamicin therapy. The correlation between transtympanic electrocochleographic (TT-ECoG) results and hydrops grade on MRI images is also investigated. Twelve definite Menière's disease patients with incapacitating vertigo attacks, not responding to drug and behavioral treatment, were selected for partial chemolabyrinthectomy with intratympanic gentamicin. All patients underwent transtympanic electrocochleography followed by surgical middle ear inspection, partial chemolabyrinthectomy (gentamicin solution 40 mg/ml applied during 60 min) and intratympanic gadolinium injection with clear exposure of the round window membrane. The MR images were reviewed and a hydrops grade was assigned. Correlation between the hydrops grade and the electrocochleographic data was assessed. Only 5 of 12 patients showed gadolinium enhancement in the inner ear. However, 6 of the 7 patients that did not show postoperative intracochlear or intralabyrinthine gadolinium distribution did report the clinical improvement after intratympanic gentamicin therapy. Hydrops grade correlated with the result of transtympanic electrocochleography in four of five cases that showed gadolinium enhancement. We conclude that the use of intratympanic gadolinium has no added value in predicting the clinical outcome of intratympanic gentamicin application. However, based on these data, a correlation between the result of TT-ECoG and hydrops grading on MRI images can be suggested.