Evaluation of the effect of dexamethasone in experimentally induced endolymphatic hydrops in guinea pigs

The Physiologic Role of Corticosteroids in Menière's Disease: An Update on Glucocorticoid-mediated Pathophysiology and Corticosteroid Inner Ear Distribution

: There are multiple treatment options for Ménière's disease (MD), including dietary modifications, aminoglycoside therapy, and surgery. All have limitations, ranging from limited effectiveness to permanent hearing loss. Corticosteroids have long been used to manage MD due to their relative efficacy and tolerability, but the exact mechanism for disease alleviation is uncertain. Until recently, the precise distribution and role that glucocorticoid receptors play in inner ear diseases have remained largely uninvestigated. Several studies propose they influence mechanisms of fluid regulation through ion and water homeostasis. This review will provide an update on the basic science literature describing the activity of endogenous glucocorticoids and exogenous corticosteroids in the inner ear and the relevance to MD, as well as early clinical trial data pertaining to the application of novel technologies for more effective administration of corticosteroids for the treatment of MD.

Systemic methylprednisolone for hearing preservation during cochlear implant surgery: A double blinded placebo-controlled trial

AIM

To assess whether a single, peri-operative, high dose of methylprednisolone can improve the preservation of residual acoustic hearing following cochlear implantation (CI).

METHODS

This was a double blinded placebo-controlled trial, performed in a tertiary academic centre. The hypothesis was that methylprednisolone would improve the preservation of hearing, and lower electrode impedances. Adult patients (18-85 years) with hearing at 85 dB or better at 500 Hz in the ear to be implanted were randomly allocated to either treatment (methylprednisolone, 1g administered intravenously upon induction of anaesthesia) or control (normal saline infusion). As per standard clinical practice, all patients received a routine dose of dexamethasone (8 mg intravenously) on induction of anaesthesia. Implantation was undertaken with a slim and flexible lateral wall electrode via the round window. Surgical technique was routine, with adherence to soft surgical principles. The primary outcome was hearing preservation within 20 dB at 500 Hz, 12 months following cochlear implantation. Secondary outcomes included hearing preservation at 6 weeks and 3 months, monopolar electrode impedance, and Consonant-Vowel-Consonant (CVC) Phoneme scores at 3 and 12 months after surgery.

RESULTS

Forty-five patients were enrolled into the control group and 48 patients received the steroid. The number of patients achieving hearing preservation at 12 months did not differ significantly between those receiving methylprednisolone treatment and the controls. There were no differences in hearing preservation at any frequency at either 6 weeks or 3 months after implantation. Neither CVC phoneme scores nor electrode impedances differed between the groups.

CONCLUSIONS

This paper demonstrates that high-dose local steroid injection at surgery was not effective in preventing a loss of residual hearing, improving speech perception, or lowering electrode impedances. The findings were contrary to the experimental literature, and emerging clinical evidence that steroid elution from implant electrodes influences cochlear biology in humans. We found no evidence to support the widely-held practice of administering intravenous steroids in the perioperative period, in an attempt to preserve residual hearing.

Middle-ear dexamethasone delivery via ultrasound microbubbles attenuates noise-induced hearing loss

OBJECTIVES/HYPOTHESIS

In this study, we expanded our previous investigation by testing the efficiency of trans-round window membrane dexamethasone (DEX) delivery mediated by ultrasound (US)-aided microbubbles (MBs) and its preventive effects regarding noise exposure in animal models.

STUDY DESIGN

Live animal model.

METHODS

Forty-two pigmented male guinea pigs were divided into the following three groups: an US-MBs (USM) group, in which the tympanic bulla was filled with DEX and MBs and exposed to US; a round window soaking (RWS) group, without the US irradiation; and a control group. The above-mentioned manipulations were performed 2 hours prior to white noise exposure. The cochlear damage, including auditory threshold shifts, hair cell loss, and expression of cochlear HMGB1, was evaluated.

RESULTS

The enhanced DEX delivery efficiency of the USM group was approximately 2.4× to 11.2× greater than that of the RWS group. After the noise exposure, the RWS group showed significant cochlear protection compared with the control group, and more significant and dominant protective effects were demonstrated in the USM group.

CONCLUSIONS

The application of US-MBs provides a safe and more effective approach than spontaneous diffusion, which is commonly used in clinical practice; thus, this technique holds potential for future inner-ear drug delivery.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:1907-1914, 2019.

The physiologic role of corticosteroids in Ménière's disease

Multiple options exist to manage Ménière's disease (MD), ranging from dietary modifications to ablative surgery. Corticosteroids (CS) have long been used to manage MD, but their exact mechanism for disease alleviation is relatively uncertain. Glucocorticoid receptors have been shown to exist in the human inner ear and several studies propose they influence mechanisms of blood flow, fluid regulation, and ion regulation, with recent evidence describing the latter two. Corticosteroids have been shown to upregulate aquaporins and ion channels in the inner ear, and may have a positive effect on labyrinthine blood flow. Additionally, processes have been described in genomic and non-genomic manners. This text will review the literature on the actions of CS on the inner ear relevant to MD.

Role of selective blocking of bradykinin receptor subtypes in attenuating allergic airway inflammation in guinea pigs

The present study was designed to evaluate the potential role of bradykinin antagonists (R-715; bradykinin B1 receptor antagonist and icatibant; bradykinin B2 receptor antagonist) in treatment of allergic airway inflammation in comparison to dexamethasone and montelukast. R-715 as dexamethasone significantly decreased peribronchial leukocyte infiltration, bronchoalveolar lavage fluid (BALF) albumin and interleukin 1β as well as serum OVA-specific IgE level. Also, R-715 like montelukast significantly decreased BALF cell count (total and eosinophils). Icatibant showed negative results. The current findings suggest that selective bradykinin B1 receptor antagonists may have the therapeutic potential for the treatment of allergic airway inflammation.

Vertigo and autoimmunity

Autoimmune inner ear disease probably accounts for less than 1% of all cases of balance disorders, but its incidence is often overlooked due to the absence of a specific diagnostic test. Furthermore, in several systemic autoimmune diseases the vestibulo-cochlear system may be affected. Clinical features comprise generalized imbalance, ataxia, motion intolerance, episodic vertigo and positional vertigo. An autoimmune mechanism seems to be responsible for 6% of unilateral and 16% of bilateral forms of Ménière's disease. Oscillopsia and disequilibrium secondary to a bilateral vestibular paresis are probably caused by an autoimmune response in 5% of cases. Balance disorders of central origin may be due to other immuno-mediated disorders such as multiple sclerosis, brainstem encephalitis and vasculitidis. Aim of this paper is to assess the clinical features of autoimmune vertigo disorders through a systematic literature review.