Evaluation of the effect of dexamethasone in experimentally induced endolymphatic hydrops in guinea pigs Fulya Ozer, MD a, 4 , Omer Faruk Unal, MD a , Ahmet Atas, PhD b , Ozgql Tekin, PhD b , Arzu Sungur, MD c ,KVvanc ¸ Ayas, MD a a Department of Otolaryngology Head and Neck Surgery, Hacettepe University Faculty of Medicine, Slhhlye, Ankara, Turkey b Audiology Unit, Hacettepe University Faculty of Medicine, Slhhlye, Ankara, Turkey c Department of Pathology, Hacettepe University Faculty of Medicine, Slhhlye, Ankara, Turkey Received 2 December 2006 Abstract Purpose: The aim of this study was to investigate the audiological and histopathologic effects of dexamethasone in the treatment of experimentally induced endolymphatic hydrops. Materials and methods: Thirty mature, male guinea pigs weighing 400 F 50 g were operated on to induce experimental endolymphatic hydrops in their right ear. Left ear served as control. Subjects were separated into control and dexamethasone groups, with the latter receiving dexamethasone 5 mg/(kg d) intraperitoneally for 10 days. Electrocochleography and auditory brainstem response were applied to all subjects at preoperation, on the second postoperative day and also on the 15th postoperative day in animals that lived for a long time. The histopathologic examination of the inner ear in all animals was done at the end of the study. Results: The summating potential and the ratio of the summating potential to the action potential measured on the second postoperative day were found to be increased in both groups, but more significantly in the control one. When the left and right ears were compared, significant difference was found in the control group; however, no significant difference was found between the ears in the dexamethasone group. Histopathologic examination revealed varying degrees of hydrops in the control group, but showed only normal findings or minor changes in the dexamethasone group. Conclusions: Dexamethasone can prevent the audiological and histopathologic findings of experimentally induced endolymphatic hydrops. However, these results must be supported by clinical and experimental studies designed with a large number of subjects. D 2008 Published by Elsevier Inc. 1. Introduction Endolymphatic hydrops is a pathology mostly seen in Meniere disease and is characterized by vertigo, tinnitus, fullness in the ear, and fluctuating hearing loss [1]. The etiopathogenesis is still unknown; and the treatment is empirical, which is usually based on reducing endolym- phatic pressure. Although treatment with diuretic agents and decompression of endolymphatic sac are frequently used, application of corticosteroid and/or gentamycin, as well as hyperbaric treatment, has been used recently [2,3]. The mechanism of corticosteroid treatment is not completely understood. Since 1979, many clinical studies have been done to evaluate the efficacy of corticosteroids [4-6]. Corticosteroid treatment is applied on the basis of prevention of many immunologic reactions that were initiated by infectious, metabolic, or traumatic reasons in the target organs such as the endolymphatic sac, stria vascularis (SV), and spiral ligament, resulting in endolym- phatic hydrops [4]. Corticosteroids have effect on the fluid- electrolyte equilibrium of the cochlea with the arrangement of Na-K ATPs enzyme on the SV [4]. This special feature of steroids was regulated by the way of mineralocorticoids 0196-0709/$ – see front matter D 2008 Published by Elsevier Inc. doi:10.1016/j.amjoto.2007.02.005 4 Corresponding author. ReYatbey Mah. 14 sok. Kaya Apt. No: 38/1, Seyhan, 01120 Adana, Turkey. Tel.: +90 322 458 6868. E-mail address: fdeveci06@hotmail.com (F. Ozer). American Journal of Otolaryngology–Head and Neck Medicine and Surgery 29 (2008) 88 – 93 Available online at www.sciencedirect.com www.elsevier.com/locate/amjoto