Effectiveness of Intratympanic Administration of Gentamicin in Unilateral MeniÈre's Disease.

Abstract

To the Editor: In a recent issue published by Otology and Neurotology, Yaz et al. (1) presented an interesting work to analyze the effectiveness of an intratympanic (IT) injection of aminoglycosides compared to intratympanic corticosteroids to control vertigo and protect hearing in Menière's disease (MD) patients with persistent vertigo attacks despite medical treatment. MD is an idiopathic inner ear disorder characterized by recurrent attacks of vertigo, accompanied by fluctuating sensorineural hearing loss, aural fullness, and tinnitus; vertigo attacks in MD are often debilitating and may severely affect quality of life. Endolymphatic hydrops (EH) of the inner ear is currently considered the pathophysiological mechanism that underlies MD symptomatology. EH seems to follow an overproduction of endolymph and/or a decrease in the absorption of endolymph as shown by histopathological research. Several therapeutic options for MD have been proposed but none is considered fully effective by the scientific community. Evidence has confirmed the importance of dietary changes in the management of MD, such as the reduction of caffeine and alcohol intake and the restriction of sodium, also suggesting introducing monosodium glutamate in patients’ diet. The article from Yaz et al. (1) is very interesting and precise; however, we would like to share some brief considerations regarding dietary changes and possible treatment options. Concerning the current discussion on the optimal dietary management in patients with MD, we would like to underline the lack of mention about glucose intake. In a recent review from our group, we remarked the possible role played by hyperinsulinemia in subjects affected by MD (2). There is actually a strong evidence that the saccule, which is the main labyrinthine structure affected following EH, has a large number of insulin receptors. This observation was confirmed by postmortem histopathological findings and by in vivo analysis through cervical vestibular evoked myogenic potentials. When first-line treatment with dietary modifications is not able to offer a satisfactory symptom control, especially of vertigo, IT administrations of corticosteroids or gentamicin is recommended; corticosteroids have been shown to have a lower risk of hearing damage but less efficacy in vertigo attack control compared to gentamicin (3). In a previous study(4), we treated 48 patients with unilateral intractable MD with IT injections (1 to 5) of 10 mg gentamicin every 2 weeks; we evaluated vertigo attacks before and after therapy and performed pure-tone audiometry, vestibular bed-side examination, and video head impulse test. Before treatment, patients had an average of 4.4 vertigo attacks/mo; after treatment the average number decreased to 0.52. The majority of patient (77%) reached vertigo control with 5 or less gentamicin injections. Although there is no current consensus on clinical guidelines for the use of gentamicin in terms of dose and duration, evidence suggests preferring low-dose protocols to minimize hearing deterioration (5). In our study, we observed that low-dose IT gentamicin can produce a satisfactory control of vertigo attacks with limited risk of hearing loss.