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throughout the cases, the thickness of the round window membrane may be the most important reason determin- ing permeability. Thus, a thickened or false round win- dow membrane could have obscured drug passage, which may be missed under the operating microscope. Another possible reason is that large endolymphatic hydrops in the vestibule may prevent the drug from moving into the vestibule. That has been shown by direct visualization of the blocked movement of intra- tympanically administered gadolinium by three- dimensional fluid-attenuated inversion recovery (3D- FLAIR) MRI. 19 This could be supported by the fact that ETG was carried out at the time of a recurrent severe vertigo attack in most cases. With regard to why ETG improved some cases, although no definite problem was found or corrected in the middle ear space, the increased contact time of gen- tamicin with the round window membrane should be considered. A previous study revealed that gadolinium contrast medium stayed in middle ear cavity for far less than 1 hour. 19 By applying gentamicin-soaked gelfoam directly on the round window membrane, the contact time could be extended considerably. ETG seems to be necessary for patients who failed to achieve sufficient attenuation of vestibular function even after three or four rounds of ITG. For intractable cases even with profound ipsilateral canal paresis after ITG/ ETG, definitive surgical ablations could be necessary because ITG/ETG could not achieve complete ablation of vestibular function. In addition, ETG or definite ablative procedures could provide additional information about undiscovered or missed disease. One patient experienced recurrent vertigo and a Tumarkin attack even after three rounds of ITG. Unilateral hearing loss had started more than 10 years previously. It was progressive, and the sub- ject has been completely deaf for the past 3 years. Unilat- eral weakness was already 77% on a bithermal caloric test prior to ITG. Because this patient had undergone brain MRIs twice during the last 2 years before visiting our clinic due to fear of cerebrovascular disorders, which were reviewed, another request for MRI was not ordered, although the previous ones were not thin-sectioned and did not include contrast enhancement. An incidental intralabyrinthine schwannoma was found during the lab- yrinthectomy. This case teaches the importance of a high index of suspicion for Menie`re’s syndrome caused by tumors and the futility or even danger of simply repeated injections. Moreover, ETG is helpful for patients who have a history of previous surgery or inflammation in the middle ear cavity. Previous studies have reported bone dust after surgical manipulation of the middle ear and obstructions caused by mucosal adhesion in patients with chronic middle ear inflammation. 14,16 Intratympanic steroid injection is one of actively per- formed procedures also in our institute; however, it is usu- ally presumed to restore recent hearing loss for those who were not responded to systemic steroid or in whom sys- temic steroid is contraindicated, but not for recurrent ver- tigo. For this reason, we did not seriously consider intratympanic steroid as an option for intractable MD and mainly used it for restoring combined acute hearing loss.

Detailed analysis of the patients with hearing improvement after ITG revealed that two of six patients experienced hearing loss with aggravation of vertigo just prior to ITG because ITG usually conducted when the symptom was aggravated. The fact that all six patients showed typical low-tone hearing loss suggests that these hearing changes could be explained by the resolution and enlargement of hydrops that usually begins at the apical turn of the cochlea. 20,21 These results also suggest that the hearing improvement in some cases might be resulted from transient hearing loss in the proximity of ITG as the enlargement of hydrops rather than a real improvement of hearing after ITG. Two patients progressed to bilateral Menie`re’s dis- ease after ITG in our study. Previous studies reported that 5% to 33.3% of unilateral Menie`re’s disease pro- gresses to bilateral disease, 22–24 and 25% to 30% of bilat- eral endolymphatic hydrops were found according to a human temporal bone study. 25,26 A more confusing issue is that most cases progress to bilateral disease serially rather than simultaneously and that contralateral dis- ease begins usually at least 2 to 5 years after the first manifestation. 27 Therefore, procedures essentially result- ing in the ablation of hearing should be performed care- fully, and ETG could be an alternative to them. For the possibility of carrying out ELSD as a sal- vage procedure after the failure of ITG, it seems to be reasonable to compare ELSD with ETG. Labyrinthec- tomy or vestibular neurectomy is far more destructive procedures than ELSD or ETG, which in turn can result in the ablation of a vestibular reflex. Our results showed complete control of vertigo (class A) with ETG in five of seven cases (71.4%). This was superior to that of ELSD (45.5% up to class A), although it was performed for failed cases of ITG. Hearing aggravation after ETG (1/7 patients; 14.3%) was slightly higher than ELSD (1/11 patients; 9.1%); however, the hearing level was not a serious matter because most patients already had more than 55 dB hearing loss. CONCLUSION ITG showed favorable vertigo control (89.5%) and hearing preservation rate (91.6%). However, 10 (10.5%) cases still suffered from intractable episodic vertigo, and six of them were revealed to have failed to achieve suffi- cient attenuation of vestibular function even after multiple ITGs. For those who have failed ITG, ETG can be consid- ered (success rate in this study: 71.4%). Labyrinthectomy or vestibular neurectomy can be chosen for those who failed to achieve vertigo control even after ETG. BIBLIOGRAPHY 1. Schessel D, Minor LB, Nedzelski J. Meniere’s disease and other peripheral vestibular disorders. In: Cummings CW, Haughey BH, Thomas JR, eds. Cummings Otolaryngology—Head and Neck Surgery (4 th ed.) Chicago IL: Mosby; 2004:3209–3253. 2. Boleas-Aguirre MS, Lin FR, La Santina CC, et al. Longitudinal results with intratympanic dexamethasone in the treatment of Meniere’s dis- ease. Otol Neurotol 2008;29:33–38. 3. Santos PM, Hall RA, Snyder JM, et al. Diuretic and diet effect on Meniere’s disease evaluated by the 1985 Committee on Hearing and Equilibrium guidelines. Otolaryngol Head Neck Surg 1993;109:680–689.

Laryngoscope 125: April 2015

Rah et al.: Intractable Menie` re’s Disease

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