Randomized, double blind, placebo controlled trial on the safety and efficacy of continuous intratympanic dexamethasone delivered via a round window catheter for severe to profound sudden idiopathic sensorineural hearing loss after failure of systemic therapy

Natural History of Untreated Idiopathic Sudden Sensorineural Hearing Loss

OBJECTIVE

Although corticosteroids and other treatments for idiopathic sudden sensorineural hearing loss (ISSNHL) have been described, understanding its prognosis without intervention provides valuable information for patient management. The objective of this study is to provide a comprehensive, quantitative statistical analysis of the natural history of untreated idiopathic sudden sensorineural hearing loss (ISSNHL).

STUDY TYPE AND DESIGN

A systematic review and meta-analyses.

METHODS

Two independent searches of PubMed, Scopus, Web of Science, and Cochrane Library databases up to June 30, 2022, were performed. Adults with idiopathic sudden sensorineural hearing loss who received placebo or were untreated and had audiometric outcome measures in all study types were reviewed. These data indicative of the natural history of ISSNHL were analyzed, as were study characteristics related to risk of bias. Heterogeneity as assessed via I2 and random effects analyses were performed.

RESULTS

Six studies meeting the inclusion criteria yielded 319 untreated patients whose natural history could be assessed. Heterogeneity among studies was moderate, with a variety of reported outcomes. A hearing improvement of at least 30 dB HL was observed in 36% (95% CI 0.28-0.44) of untreated patients, and of at least 10 dB HL was observed in 70% (95% CI 0.57-0.82) of untreated patients at 3 months. The mean hearing gain among untreated patients was 24.0 dB HL (95% CI 2.65-45.37) at 2-3 months.

CONCLUSIONS

The observed natural history of ISSNHL suggests that patients can regain some hearing without active treatment. In the absence of future studies collecting prospective natural history data from untreated or placebo-treated ISSNHL patients, the data presented here provide the best available historical control data for reconsideration of results in past ISSNHL studies, as well as a roadmap for design and interpretation of future ISSNHL treatment clinical trials. Furthermore, knowing there is a statistically significant mean hearing gain of 24.0 dB HL in the untreated/placebo group provides an ethical basis for future placebo study of ISSNHL. The current status on ISSNHL management calls for a multi-institutional, randomized, double-blind placebo-controlled trial with validated outcome measures to provide science-based treatment guidance. Laryngoscope, 134:S1-S15, 2024.

Clinical efficacy of intratympanic steroid injection for treating idiopathic sudden sensorineural hearing loss

BACKGROUND

Idiopathic sudden sensorineural hearing loss (ISSNHL) is an emergency that causes permanent hearing loss if timely treatment is not provided. However, the evidence supporting the effect of intratympanic steroid injection (ITSI) starting time on hearing outcome is limited.

METHODS

We retrospectively enrolled 582 patients with ISSNHL who were treated with ITSIs and reviewed their clinical and audiological variables. The relationship between ITSI starting time and hearing recovery was analyzed.

RESULTS

The mean starting time of ITSI was 13.17 ± 16.53 days. The overall hearing recovery rate was 55.15% (recovery = mean hearing level gain of ≥10 dB). The recovery rates were 79.2%, 67.4%, 50%, 36.6%, and 17.8% for the ITSI starting times of 1 to 3, 4 to 7, 8 to 14, 15 to 28, and ≥29 days, respectively. A multivariate analysis revealed that ITST starting time (odds ratio [OR] = 0.94, 95% CI, 0.92-0.96, p < 0.001) and salvage therapy (OR = 0.55, 95% CI, 0.35-0.86, p = 0.009) were independent poor prognostic factors for patients with ISSNHL.

CONCLUSION

Earlier ITSI treatment is associated with a higher hearing recovery rate. Comorbidities and post-ITSI complications were nonsignificant independent risk factors.

Salvage therapy for refractory sudden sensorineural hearing loss (RSSNHL): a systematic review and network meta-analysis

OBJECTIVE

Approximately 30-50% of sudden sensorineural hearing loss (SSNHL) patients show poor response to systemic steroid therapy. Additionally, the most appropriate treatment for patients with refractory sudden sensorineural hearing loss (RSSNHL) is unknown. This study aimed to explore the best treatment for RSSNHL.

DESIGN

Using a frequentist contrast-based model and PRISMA guidelines, this study compared five salvage regimes: intratympanic injection of steroids (ITS), hyperbaric oxygen (HBO) therapy, post auricle steroid injection (PSI), ITS combined with HBO therapy, and continued systemic steroids.

STUDY SAMPLE

We searched the PubMed, EMBASE, Web of Science, and Cochrane Library databases for randomised controlled trials and cohort studies comparing treatment regimens for RSSNHL.

RESULTS

Compared with the control group (no additional treatment), PSI and ITS demonstrated significant improvements. The mean hearing gain was greater after PSI (11.1 dB [95% CI, 4.4-17.9]) than after ITS (7.7 dB [95% CI, 4.8-10.7]). When a restricted definition of RSSNHL was used, the ITS + HBO therapy showed the largest difference in improvement for pure tone average compared with the control group (14.5 dB [95% CI, 4.2-25.0]).

CONCLUSIONS

The administration of either PSI or ITS leads to the greatest therapeutic effect in patients with RSSNHL. However, a consensus on the definition of RSSNHL is needed.

Sound conditioning strategy promoting paracellular permeability of the blood-labyrinth-barrier benefits inner ear drug delivery

The therapeutic effects of pharmaceuticals depend on their drug concentrations in the cochlea. Efficient drug delivery from the systemic circulation into the inner ear is limited by the blood-labyrinth-barrier (BLB). This study investigated a novel noninvasive sound conditioning (SC) strategy (90 dB SPL, 8-16 kHz, 2 h sound exposure) to temporally enhance BLB permeability in a controllable way, contributing to maximizing the penetration of pharmaceuticals from blood circulation into the cochlea. Trafficking of Fluorescein Isothiocyanate conjugated dextran and bovine serum albumin (FITC-dextran and FITC-BSA) demonstrated that paracellular leakage of BLB sustained for 6 h after SC, providing a controllable time window for systemic administration. Cochlear concentrations of dexamethasone (DEX) and dexamethasone phosphate (DEX-P), respectively transported by transcellular and paracellular pathways, showed a higher content of the latter one after SC, further confirming the key role of paracellular pathway in the SC-induced hyperpermeability. Results of high-throughput RNA-sequencing identified a series of tight junction (TJ)-associated genes after SC. The expressions of TJ (ZO-1) were reduced and irregular rearrangements of the junction were observed by transmission electron microscopy after SC. We further determined the inhibiting role of Rab13 in the recruitment of ZO-1 and later in the regulation of cellular permeability. Meanwhile, no significant change in the quantifications of endothelial caveolae vesicles after SC indicated that cellular transcytosis accounted little for the temporary hyperpermeability after SC. Based on these results, SC enhances the BLB permeability within 6 h and allows systemically applied drugs which tend to be transported by paracellular pathway to readily enter the inner ear, contributing to guiding the clinical medications on hearing loss.

Micro Injection Molding of Drug-Loaded Round Window Niche Implants for an Animal Model Using 3D-Printed Molds

A novel approach for the long-term medical treatment of the inner ear is the diffusion of drugs through the round window membrane from a patient-individualized, drug-eluting implant, which is inserted in the middle ear. In this study, drug-loaded (10 wt% Dexamethasone) guinea pig round window niche implants (GP-RNIs, ~1.30 mm × 0.95 mm × 0.60 mm) were manufactured with high precision via micro injection molding (µIM, T_mold = 160 °C, crosslinking time of 120 s). Each implant has a handle (~3.00 mm × 1.00 mm × 0.30 mm) that can be used to hold the implant. A medical-grade silicone elastomer was used as implant material. Molds for µIM were 3D printed from a commercially available resin (T_G = 84 °C) via a high-resolution DLP process (xy resolution of 32 µm, z resolution of 10 µm, 3D printing time of about 6 h). Drug release, biocompatibility, and bioefficacy of the GP-RNIs were investigated in vitro. GP-RNIs could be successfully produced. The wear of the molds due to thermal stress was observed. However, the molds are suitable for single use in the µIM process. About 10% of the drug load (8.2 ± 0.6 µg) was released after 6 weeks (medium: isotonic saline). The implants showed high biocompatibility over 28 days (lowest cell viability ~80%). Moreover, we found anti-inflammatory effects over 28 days in a TNF-α-reduction test. These results are promising for the development of long-term drug-releasing implants for human inner ear therapy.

Intratympanic Substance Distribution After Injection of Liquid and Thermosensitive Drug Carriers: An Endoscopic Study

OBJECTIVE

In the treatment of inner ear conditions, intratympanic injection emerges as an important drug delivery method. Novel compounds designed for intratympanic injection are routinely loaded in viscous drug carriers. To date, it is unclear if they can freely distribute in the middle ear. The aims of this study were to investigate the middle ear distribution of different drug carriers during intratympanic injection and to determine an optimal injection method for thermosensitive hydrogels.

METHODS

Twenty-one human temporal bones were intratympanically injected with fluid drug carriers or poloxamer-407 hydrogels at different tympanic membrane injection sites (inferior, anterior-superior) using different needle types (Whitacre, Quincke). Fluid distribution was evaluated via an endoscopic view. Injection volume, duration, backflow, and overall safety were analyzed.

RESULTS

Liquid drug carriers distribute effortlessly in the middle ear, whereas an additional ventilation hole is advantageous when applying thermosensitive hydrogels. The round window is coated with required volumes between 150 and 200 μl, irrespective of the injection position. Required volumes to also coat the stapedial footplate ranged from 310 to 440 μl. Use of the Whitacre-type needle reduced backflow to the ear canal and enabled longer tympanic membrane visibility when no additional ventilation hole was placed.

CONCLUSION

Intratympanic injection is a safe and reliable method for the application of thermosensitive hydrogels. The round window niche is readily filled regardless of the injected formulation and injection position. Although fluid drug carriers distribute effortlessly in the middle ear, the placement of an additional ventilation hole might facilitate the application of viscous hydrogels.

Intratympanic Dexamethasone in Sudden Sensorineural Hearing Loss

Sudden sensorineural hearing loss can be a frightening experience for the sufferer and needs immediate treatment. Systemic steroid therapy has been the mainstay of treatment of this condition but concerns about their side effects has led to their use by intratympanic injection. We studied the results of intratympanic dexamethasone (IT-Dexa) both as a primary therapy and as salvage treatment after failure of oral steroids. A total of 39 patients of SSNHL were studied prospectively. Of these 23 were given oral steroids. Ten of these showed no response and were treated with IT-Dexa 4 mg/ml twice a week for two weeks. In addition, 16 patients who reported later than two weeks or had concomitant medical disorders like diabetes and/or hypertension were treated with IT-Dexa. While oral steroids showed hearing improvement (≥ 10 dB) in 56.5% patients, the recovery rate was 62.5% and 80% in those treated primarily with IT-Dexa and as salvage therapy respectively. There was a negative correlation of delay in institution of treatment with hearing recovery. Conclusion: intratympanic dexamethasone is a safe and effective treatment and should be offered to patients as a primary treatment modality and also as salvage therapy after failure of oral steroids. For best results the treatment should be started at the earliest.

Analysis of the Efficacy and Safety of Intratymapanic Dexamethasone for Treating Meniere's Disease: A Randomized Controlled Trial

OBJECTIVES

Our objective was to study the efficacy and safety of intratymapanic dexamethasone (ITD) for treating in Méniere's disease in southern China.

METHODS

A total of 124 patients with Méniere's disease were randomly divided into 2 groups: ITD group (n = 62) and intratympanic lidocaine (ITL) group (n = 62). The ITD group was further randomly divided into 2 groups based on dexamethasone dosage: ITD1 (2 mg/ml) (n = 31) and ITD2 (5 mg/ml) group (n = 31). Symptom alleviation and complications were recorded after every treatment.

RESULTS

Vertigo was improved in 65% of patients who received ITD compared with 55% of patients who received ITL patients (P < .05). Three patients in the ITD2 group had from otomycosis, and 2 of these patients had a perforation; no tympanic membrane perforation was observed in the ITL and ITD1 group.

CONCLUSIONS

Compared with lidocaine, dexamethasone is more effective in alleviating vertigo, and a lower concentration of dexamethasone can reduce the occurrence of complications.

Safety and audiological outcome in a case series of tertiary therapy of sudden hearing loss with a biodegradable drug delivery implant for controlled release of dexamethasone to the inner ear

Background

Intratympanic injections of glucocorticoids have become increasingly common in the treatment of idiopathic sudden sensorineural hearing loss (ISSHL). However, due to their fast elimination, sustained applications have been suggested for local drug delivery to the inner ear.

Materials and methods

The study is based on a retrospective chart review of patients treated for ISSHL at a single tertiary (university) referral center. We included patients who were treated with a solid, biodegradable, poly(D,L-lactic-co-glycolic acid) (PLGA)-based drug delivery system providing sustained delivery of dexamethasone extracochlear into the round window niche (n = 15) or intracochlear into scala tympani (n = 2) for tertiary therapy of ISSHL in patients without serviceable hearing after primary systemic and secondary intratympanic glucocorticoid therapy. We evaluated the feasibility and safety through clinical evaluation, histological examination, and functional tests [pure-tone threshold (PTA), word recognition scores (WRS)].

Results

With adequate surgical preparation of the round window niche, implantation was feasible in all patients. Histologic examination of the material in the round window niche showed signs of resorption without relevant inflammation or foreign body reaction to the implant. In patients where the basal part of scala tympani was assessable during later cochlear implantation, no pathological findings were found. In the patients with extracochlear application, average preoperative PTA was 84.7 dB HL (SD: 20.0) and 76.7 dB HL (SD: 16.7) at follow-up (p = 0.08). The preoperative average maximum WRS was 14.6% (SD: 17.9) and 39.3% (SD: 30.7) at follow-up (p = 0.11). Six patients (40%), however, reached serviceable hearing. The two patients with intracochlear application did not improve.

Conclusion

The extracochlear application of the controlled release system in the round window niche and – based on limited observations - intracochlear implantation into scala tympani appears feasible and safe. Due to the uncontrolled study design, conclusions about the efficacy of the treatment are limited. These observations, however, may encourage the initiation of prospective controlled studies using biodegradable controlled release implants as drug delivery systems for the treatment of inner ear diseases.

Probability of clinically significant hearing recovery following salvage intratympanic steroids for sudden sensorineural hearing loss in the ‘real world’

Objective

This study aimed to determine the probability of hearing recovery in patients with idiopathic sudden sensorineural hearing loss following salvage intratympanic steroids

Method

A retrospective review of all patients receiving salvage intratympanic steroid injections for idiopathic sudden sensorineural hearing loss was performed (January 2014 to December 2019). Twenty-two patients were identified, of whom 15 met inclusion criteria. Pre- and post-treatment audiograms were compared with the unaffected ear. Hearing recovery was categorised based on American Academy of Otolaryngology Head and Neck Surgery criteria.

Results

Only 1 patient out of 15 (6.7 per cent) made a partial recovery, and the remainder were non-responders. The median duration of time between symptom onset and first salvage intratympanic steroid treatment was 52 days (range, 14–81 days). No adverse reactions were observed.

Conclusion

‘Real world’ patients with idiopathic sudden sensorineural hearing loss present differently to those in the literature. Sudden sensorineural hearing loss should be diagnosed with care and intratympanic steroid injections initiated early if considered appropriate. Patients should make an informed decision on treatment based on prognostic factors and local success rates.

Rationally Designed Magnetic Nanoparticles for Cochlear Drug Delivery: Synthesis, Characterization, and In Vitro Biocompatibility in a Murine Model

Hypothesis

Magnetic nanoparticles (MNPs) for cochlear drug delivery can be precisely engineered for biocompatibility in the cochlea.

Background

MNPs are promising drug delivery vehicles that can enhance the penetration of both small and macromolecular therapeutics into the cochlea. However, concerns exist regarding the application of oxidative, metal-based nanomaterials to delicate sensory tissues of the inner ear. Translational development of MNPs for cochlear drug deliver requires specifically tuned nanoparticles that are not cytotoxic to inner ear tissues. We describe the synthesis and characterization of precisely tuned MNP vehicles, and their in vitro biocompatibility in murine organ of Corti organotypic cultures.

Methods

MNPs were synthesized via 2-phase ligand transfer process with precise control of nanoparticle size. Core and hydrodynamic sizes of nanoparticles were characterized using electron microscopy and dynamic light scattering, respectively. In vitro biocompatibility was assayed via mouse organ of Corti organotypic cultures with and without an external magnetic field gradient. Imaging was performed using immunohistochemical labeling and confocal microscopy. Outer hair cell, inner hair cell, and spiral ganglion neurites were individually quantified.

Results

Monocore PEG-MNPs of 45 and 148 nm (mean hydrodynamic diameter) were synthesized. Organ of Corti cultures demonstrated preserved outer hair cell, inner hair cell, and neurite counts across 2 MNP sizes and doses, and irrespective of external magnetic field gradient.

Conclusion

MNPs can be custom-synthesized with precise coating, size, and charge properties specific for cochlear drug delivery while also demonstrating biocompatibility in vitro.

Intratympanic corticosteroids for sudden sensorineural hearing loss

BACKGROUND

Idiopathic sudden sensorineural hearing loss (ISSNHL) is common, and defined as a sudden decrease in sensorineural hearing sensitivity of unknown aetiology. Systemic corticosteroids are widely used, however their value remains unclear. Intratympanic injections of corticosteroids have become increasingly common in the treatment of ISSNHL.

OBJECTIVES

To assess the effects of intratympanic corticosteroids in people with ISSNHL.

SEARCH METHODS

The Cochrane ENT Information Specialist searched the Cochrane ENT Trials Register; CENTRAL (2021, Issue 9); PubMed; Ovid Embase; CINAHL; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials (search date 23 September 2021).

SELECTION CRITERIA

We included randomised controlled trials (RCTs) involving people with ISSNHL and follow-up of over a week. Intratympanic corticosteroids were given as primary or secondary treatment (after failure of systemic therapy).

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods, including GRADE to assess the certainty of the evidence. Our primary outcome was change in hearing threshold with pure tone audiometry. Secondary outcomes included the proportion of people whose hearing improved, final hearing threshold, speech audiometry, frequency-specific hearing changes and adverse effects.

MAIN RESULTS

We included 30 studies, comprising 2133 analysed participants. Some studies had more than two treatment arms and were therefore relevant to several comparisons. Studies investigated intratympanic corticosteroids as either primary (initial) therapy or secondary (rescue) therapy after failure of initial treatment. 1. Intratympanic corticosteroids versus systemic corticosteroids as primary therapy We identified 16 studies (1108 participants). Intratympanic therapy may result in little to no improvement in the change in hearing threshold (mean difference (MD) -5.93 dB better, 95% confidence interval (CI) -7.61 to -4.26; 10 studies; 701 participants; low-certainty). We found little to no difference in the proportion of participants whose hearing was improved (risk ratio (RR) 1.04, 95% CI 0.97 to 1.12; 14 studies; 972 participants; moderate-certainty). Intratympanic therapy may result in little to no difference in the final hearing threshold (MD -3.31 dB, 95% CI -6.16 to -0.47; 7 studies; 516 participants; low-certainty). Intratympanic therapy may increase the number of people who experience vertigo or dizziness (RR 2.53, 95% CI 1.41 to 4.54; 1 study; 250 participants; low-certainty) and probably increases the number of people with ear pain (RR 15.68, 95% CI 6.22 to 39.49; 2 studies; 289 participants; moderate-certainty). It also resulted in persistent tympanic membrane perforation (range 0% to 3.9%; 3 studies; 359 participants; very low-certainty), vertigo/dizziness at the time of injection (1% to 21%, 3 studies; 197 participants; very low-certainty) and ear pain at the time of injection (10.5% to 27.1%; 2 studies; 289 participants; low-certainty). 2. Intratympanic plus systemic corticosteroids (combined therapy) versus systemic corticosteroids alone as primary therapy We identified 10 studies (788 participants). Combined therapy may have a small effect on the change in hearing threshold (MD -8.55 dB better, 95% CI -12.48 to -4.61; 6 studies; 435 participants; low-certainty). The evidence is very uncertain as to whether combined therapy changes the proportion of participants whose hearing is improved (RR 1.27, 95% CI 1.15 to 1.41; 10 studies; 788 participants; very low-certainty). Combined therapy may result in slightly lower (more favourable) final hearing thresholds but the evidence is very uncertain, and it is not clear whether the change would be important to patients (MD -9.11 dB, 95% CI -16.56 to -1.67; 3 studies; 194 participants; very low-certainty). Some adverse effects only occurred in those who received combined therapy. These included persistent tympanic membrane perforation (range 0% to 5.5%; 5 studies; 474 participants; very low-certainty), vertigo or dizziness at the time of injection (range 0% to 8.1%; 4 studies; 341 participants; very low-certainty) and ear pain at the time of injection (13.5%; 1 study; 73 participants; very low-certainty).  3. Intratympanic corticosteroids versus no treatment or placebo as secondary therapy We identified seven studies (279 participants). Intratympanic therapy may have a small effect on the change in hearing threshold (MD -9.07 dB better, 95% CI -11.47 to -6.66; 7 studies; 280 participants; low-certainty). Intratympanic therapy may result in a much higher proportion of participants whose hearing is improved (RR 5.55, 95% CI 2.89 to 10.68; 6 studies; 232 participants; low-certainty). Intratympanic therapy may result in lower (more favourable) final hearing thresholds (MD -11.09 dB, 95% CI -17.46 to -4.72; 5 studies; 203 participants; low-certainty). Some adverse effects only occurred in those who received intratympanic injection. These included persistent tympanic membrane perforation (range 0% to 4.2%; 5 studies; 185 participants; very low-certainty), vertigo or dizziness at the time of injection (range 6.7% to 33%; 3 studies; 128 participants; very low-certainty) and ear pain at the time of injection (0%; 1 study; 44 participants; very low-certainty).  4. Intratympanic plus systemic corticosteroids (combined therapy) versus systemic corticosteroids alone as secondary therapy We identified one study with 76 participants. Change in hearing threshold was not reported. Combined therapy may result in a higher proportion with hearing improvement, but the evidence is very uncertain (RR 2.24, 95% CI 1.10 to 4.55; very low-certainty). Adverse effects were poorly reported with only data for persistent tympanic membrane perforation (rate 8.1%, very low-certainty).

AUTHORS' CONCLUSIONS

Most of the evidence in this review is low- or very low-certainty, therefore it is likely that further studies may change our conclusions.   For primary therapy, intratympanic corticosteroids may have little or no effect compared with systemic corticosteroids. There may be a slight benefit from combined treatment when compared with systemic treatment alone, but the evidence is uncertain. For secondary therapy, there is low-certainty evidence that intratympanic corticosteroids, when compared to no treatment or placebo, may result in a much higher proportion of participants whose hearing is improved, but may only have a small effect on the change in hearing threshold. It is very uncertain whether there is additional benefit from combined treatment over systemic steroids alone. Although adverse effects were poorly reported, the different risk profiles of intratympanic treatment (including tympanic membrane perforation, pain and dizziness/vertigo) and systemic treatment (for example, blood glucose problems) should be considered when selecting appropriate treatment.

Efficacy and safety of systemic, high-dose glucocorticoid therapy for idiopathic sudden sensorineural hearing loss : Study protocol for a three-armed, randomized, triple-blind, multicenter trial (HODOKORT)

BACKGROUND

Systemic glucocorticosteroids ("steroids") are widely used worldwide as a standard of care for primary therapy of idiopathic sudden sensorineural hearing loss (ISSHL). The German ISSHL guideline recommends high-dose steroids without evidence from randomized controlled trials (RCTs) and refers solely to retrospective cohort studies. This RCT aims to assess the efficacy (improvement in hearing) and safety (especially systemic side effects) of high-dose steroids versus standard of care (standard dose systemic steroids) for the treatment of unilateral ISSHL, when given as a primary therapy.

METHODS

The study is designed as a multicenter (approximately 40 centers), randomized, triple-blind, three-armed, parallel group, clinical trial with 312 adult patients. The interventions consist of 5 days of 250 mg/day intravenous prednisolone (intervention 1) + oral placebo, or 5 days of 40 mg/day oral dexamethasone (intervention 2) + intravenous placebo. The control intervention consists of 60 mg oral prednisolone for 5 days followed by five tapering doses + intravenous placebo. The primary efficacy endpoint is the change in hearing threshold in the three most affected contiguous frequencies between 0.25 and 8 kHz 1 month after ISSHL. Secondary endpoints include further measures of hearing improvement including speech audiometry, tinnitus, quality of life, blood pressure, and altered glucose tolerance.

DISCUSSION

There is an unmet medical need for an effective medical therapy of ISSHL. Although sensorineural hearing impairment can be partially compensated by hearing aids or cochlear implants (CI), generic hearing is better than using hearing aids or CIs. Since adverse effects of a short course of high-dose systemic corticosteroids have not been documented with good evidence, the trial will improve knowledge on possible side effects in the different treatment arms with a focus on hyperglycemia and hypertension.

TRIAL REGISTRATION

EudraCT (European Union Drug Regulating Authorities Clinical Trials Database) Nr. 2015-002602-36; Sponsor code: KKSH-127.

A forskolin-loaded nanodelivery system prevents noise-induced hearing loss

Hearing loss is the most common sensory disorder worldwide and may result from age, drugs, or exposure to excessive noise. Crossing the blood-labyrinth barrier to achieve targeted drug delivery to the inner ear is key to the treatment of hearing loss. We designed a nanoparticle (NP)-based system for targeted drug delivery of forskolin (FSK) to the inner ear, driven by the prestin-targeting peptide LS19 ("ligand-receptor type interaction"). In vivo experiments in developing zebrafish embryos (4-96 h past fertilization) and mice confirmed that LS19-FSK specifically targeted and accumulated in zebrafish lateral line neuromasts and mouse outer hair cells (OHCs). LS19 peptide modification enabled LS19-FSK-NPs to rapidly target OHCs with high specificity. Furthermore, the multifunctional LS19-FSK-NPs were successfully delivered to the OHCs via the round window membrane route and exhibited slow-release properties. The sustained release and intracellular accumulation of FSK inhibited apoptosis of OHCs. Compared with LS19-NPs and FSK-NPs, LS19-FSK-NPs provided significantly stronger protection against noise-induced hearing damage, based on auditory brainstem responses at 4, 8, 16, and 32 kHz. Thus, our specially designed targeted nano-delivery system may serve as a basis for future clinical applications and treatment platforms and has the potential to significantly improve the treatment results of many inner ear diseases.

[Glucocorticosteroids in the treatment of acute neurosensory hearing loss. The current state of the problem. Part 2]

Modern literature data are presented on the choice of a drug for hormonal therapy in acute neurosensory hearing loss of various origins, the doses used for systemic therapy, the features and methods of intratympanic administration of glucocorticosteroids, and the evaluation of the effectiveness of treatment with this group of drugs.

Dexamethasone for Inner Ear Therapy: Biocompatibility and Bio-Efficacy of Different Dexamethasone Formulations In Vitro

Dexamethasone is widely used in preclinical studies and clinical trials to treat inner ear disorders. The results of those studies vary widely, maybe due to the different dexamethasone formulations used. Laboratory (lab) and medical grade (med) dexamethasone (DEX, C₂₂H₂₉FO₅) and dexamethasone dihydrogen phosphate-disodium (DPS, C₂₂H₂₈FNa₂O₈P) were investigated for biocompatibility and bio-efficacy in vitro. The biocompatibility of each dexamethasone formulation in concentrations from 0.03 to 10,000 µM was evaluated using an MTT assay. The concentrations resulting in the highest cell viability were selected to perform a bio-efficiency test using a TNFα-reduction assay. All dexamethasone formulations up to 900 µM are biocompatible in vitro. DPS-lab becomes toxic at 1000 µM and DPS-med at 2000 µM, while DEX-lab and DEX-med become toxic at 4000 µM. Bio-efficacy was evaluated for DEX-lab and DPS-med at 300 µM, for DEX-med at 60 µM, and DPS-lab at 150 µM, resulting in significantly reduced expression of TNFα, with DPS-lab having the highest effect. Different dexamethasone formulations need to be applied in different concentration ranges to be biocompatible. The concentration to be applied in future studies should carefully be chosen based on the respective dexamethasone form, application route and duration to ensure biocompatibility and bio-efficacy.

Approaches for ear-targeted delivery systems in neurosensory disorders to avoid chronic hearing loss mediated neurological diseases

BACKGROUND & OBJECTIVE

Hearing loss is a common audio-vestibular-related neurosensory disability of inner ears, in which patients exhibit clinical symptoms of dizziness, gait unsteadiness, and oscillopsia, at an initial stage. While, if such disorders are untreated for a prolonged duration then the progression of disease into a chronic state significantly decreases GABA level as well as an alteration in the neurotransmission of CNS systems. Hence, to control the progression of disease into a chronic state, timely and targeted delivery of the drug into the site of action in the ear is now attracting the interest of neurologists for effective and safe treatment of such disorders. Among delivery systems, owing to small dimension, better penetration, rate-controlled release, higher bioavailability; nanocarriers are preferred to overcome delivery barriers, improvement in residence time, and enhanced the performance of loaded drugs. Subsequently, these carriers also stabilize encapsulated drugs while the opportunity to modify the surface of carriers favors guided direction for site-specific targeting. Conventional routes of drug delivery such as oral. intravenous, and intramuscular are poorer in performance because of inadequate blood supply to the inner ear and limited penetration of blood-inner ear barrier.

CONCLUSION

This review summarized novel aspects of non-invasive and biocompatible nanoparticles-based approaches for targeted delivery of drugs into the cochlea of the ear to reduce the rate, and extent of the emergence of any hearing loss mediated neurological disorders.

Idiopathic Sudden Sensorineural Hearing Loss: Speech Intelligibility Deficits Following Threshold Recovery

OBJECTIVES

This retrospective study tests the hypothesis that patients who have recovered from idiopathic sudden sensorineural hearing loss (SSNHL) show deficits in word recognition tasks that cannot be entirely explained by a loss in audibility.

DESIGN

We reviewed the audiologic profile of 166 patients presenting with a unilateral SSNHL. Hearing loss severity, degree of threshold recovery, residual hearing loss, and word recognition performance were considered as outcome variables. Age, route of treatment, delay between SSNHL onset and treatment, and audiogram configuration were considered as predictor variables.

RESULTS

Severity, residual hearing loss, and recovery were highly variable across patients. While age and onset-treatment delay could not account for the severity, residual hearing loss and recovery in thresholds, configuration of the SSNHL and overall inner ear status as measured by thresholds on the contralateral ear were predictive of threshold recovery. Speech recognition performance was significantly poorer than predicted by the speech intelligibility curve derived from the patient's audiogram.

CONCLUSIONS

SSNHL is associated with (1) changes in thresholds that are consistent with ischemia and (2) speech intelligibility deficits that cannot be entirely explained by a change in hearing sensitivity.

Steroid Nomenclature in Inner Ear Therapy

: Local glucocorticosteroid ("steroid") therapy is widely used to treat the inner ears of patients with Menière's disease, idiopathic sudden sensorineural hearing loss and in combination with cochlear implants. Applied steroids have included dexamethasone, methylprednisolone, and triamcinolone. In reality, however, this is often not true and the steroid forms commonly applied are dexamethasone-phosphate, methylprednisolone-hemisuccinate, or triamcinolone-acetonide. In each case, the additional component is not a counter-ion but is covalently bound to the molecule to increase aqueous solubility or potency. These drug forms are approved for intravenous or intramuscular delivery and are used "off-label" in the ear. When given systemically, the molecular form of the drug is of minor importance as the drugs are rapidly metabolized. In contrast, when administered intratympanically, the exact form of the drug has a major influence on entry into perilymph and elimination from perilymph, which in turn influences distribution along the cochlear scalae. Dexamethasone-phosphate has completely different molecular properties to dexamethasone and has different pharmacokinetic properties entering and leaving perilymph. Molecular properties and perilymph pharmacokinetics also differ markedly for triamcinolone and triamcinolone-acetonide. Methylprednisolone-hemisuccinate has completely different molecular properties to methylprednisolone. In the ear, different steroid forms cannot therefore be regarded as equivalent in terms of pharmacokinetics or efficacy. This presents a terminology problem, where in many cases the drug stated in publications may not be the form actually administered. The lack of precision in nomenclature is a serious problem for the inner ear drug delivery field and needs to be recognized.

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.

Idiopathic sudden sensorineural hearing loss: Effectiveness of salvage treatment with low-dose intratympanic dexamethasone

Objectives

To evaluate hearing outcome of salvage treatment with intratympanic steroids (ITS) in idiopathic sudden sensorineural hearing loss (ISSNHL) refractory to initial systemic steroid (SS) therapy.

Material and methods

A retrospective medical chart review was conducted on 54 consecutive patients with ISSNHL refractory to SS. Salvage treatment with a low dose intratympanic dexamethasone (4 mg/ml) was offered after one week of primary treatment. Patients were divided into two groups: 25 patients accepted ITS (treatment group) and 29 patients did not undergo additional treatment (control group). A pure tone average (PTA) gain of at least 10 dB was considered hearing improvement.

Results

Hearing improvement rate was higher in ITS group compared to control group (40% vs. 13.8%, p = 0.035). A mean PTA improvement of 8.6 ± 9.8 dB was observed in the ITS group and, whereas the control group had an average hearing gain of 0.7 ± 2 dB (p < 0.001). Audiometric analysis revealed a significant hearing gain in ITS group at all tested frequencies compared to control group (p < 0.05). Analysis of the selected variables, identified intratympanic steroid treatment as the only independent prognostic factor for hearing improvement (OR = 4.2, 95% CI: 1.1-15.7; p = 0.04).

Conclusion

Intratympanic low dose dexamethasone is effective in patients with incomplete hearing recovery after primary systemic steroid treatment.

Differences in hearing recovery following intratympanic alone or intravenous dexamethasone with rescue intratympanic steroids for sudden sensorineural hearing loss: A randomised trial

OBJECTIVES

This study aimed to evaluate hearing improvement at different frequencies and the safety of intratympanic (IT) and intravenous (IV) administration of dexamethasone for sudden sensorineural hearing loss (SSNHL).

METHODS

SSNHL patients were randomly divided into two groups within 72 hours after onset and received 24 days of dexamethasone therapy. Group A received IT dexamethasone once every other day for 24 days. Group B received IV dexamethasone for 12 days, followed by IT dexamethasone once every other day for the following 12 days. Hearing recovery and side effects were compared.

RESULTS

Subgroup analysis was performed to look for variation in hearing improvement in high frequency, low frequency and overall hearing at different time points. There was no evidence of a difference in hearing outcomes between IT dexamethasone and sequential IV plus IT treatments. Side effects of steroids were observed within 90 days after treatment. The local adverse effects of IT injection were mild. The systemic side effects in group B were more serious than those in group A.

CONCLUSIONS

IT dexamethasone was safer than IV dexamethasone, and there was no evidence of a difference in hearing outcomes between IT dexamethasone and sequential IV plus IT treatments. It is necessary to make individualised treatment decisions according to the patient's condition.

Impacts of different methylprednisolone administration routes in patients with sudden hearing loss or Meniere's disease

BACKGROUND

Evidence suggests that glucocorticoids are important in the treatment of sudden hearing loss (SHL) and Meniere's disease (MD). However, different glucocorticoid administration methods may have a significant impact on treatment outcomes.

OBJECTIVE

This study aimed to investigate effects of different glucocorticoid administration methods on sudden hearing loss and Meniere's disease.

METHODS

In this study, glucocorticoids were administered orally in 18 patients, by retroauricular injection in 15 patients and by intratympanic injection in 15 patients. White blood cell (WBC) count, serum K+, fasting plasma glucose (FPG), body temperature, heart rate and blood pressure were used to evaluate effects of glucocorticoids on patients with hearing loss. Visual analog scale (VAS) of pain and sleep disorders were also surveyed, and pure tone audiometry (PTA) results were compared among groups to evaluate efficacy of different glucocorticoids administration methods.

RESULT

WBC count, heart rate and blood pressure were higher in patients taking oral glucocorticoids, while body temperature, serum K+ and FPG levels did not change in all three groups. However, patients who received intratympanic injection of glucocorticoids experienced more pain, while those taking oral glucocorticoids reported more sleep impairment. Treatment efficacy on hearing loss was not significantly different among the three groups.

CONCLUSION

These findings suggest that systemic glucocorticoid administration can result in greater whole body responses than local administration, but with similar hearing treatment efficacy.

Development of nanoparticle drug-delivery systems for the inner ear

Hearing loss has become the most common sensory nerve disorder worldwide, with no effective treatment strategy. Low-permeability and limited blood supply to the blood-labyrinth barrier limit the effective delivery and efficacy of therapeutic drugs in the inner ear. Nanoparticle (NP)-based drugs have shown benefits of stable controlled release and functional surface modification, and NP-based delivery systems have become a research hotspot. In this review, we discuss the development of new targeted drug-delivery systems based on the biocompatibility and safety of different NPs in the cochlea, as well as the advantages and disadvantages of their prescription methods and approaches. We believe that targeted NP-based drug-delivery systems will be effective treatments for hearing loss.

Intratympanic injection of dexamethasone 4 mg/mL versus 10 mg/mL for management of idiopathic sudden sensorineural hearing loss

Background

The aim of this study was to determine whether different concentrations of intratympanic (IT) injection of dexamethasone at a dose of 4 and 10 mg/mL have an effect on hearing outcomes in patients with idiopathic sudden sensorineural hearing loss (ISSNHL).

Results

Our study was conducted on 30 adult patients with unilateral ISSNHL who failed to respond or with contraindications to systemic steroids. Patients were categorized into two groups; each one included 15 patients. IT injection of 4 mg/mL dexamethasone was done in one group (IT dexamethasone (Dex) 4 mg/mL), while 10 mg/mL dexamethasone was administered intratympanically in the other group (IT Dex 10 mg/mL). IT injection was performed twice weekly for two successive weeks. PTA thresholds were assessed at 0.5, 1, 2 and 4 kHz before and 1 month after the treatment.

In the group with IT Dex 10 mg/mL, the average PTA improved significantly from 75.50 ± 12.59 to 49 ± 24.04 dB with an average gain of 26.50 ± 14.25 (p = 0.0007). In the group with IT Dex 4 mg/mL, there was a significant change of PTA from a pretreatment value of 76.92 ± 11.89 dB to a post-treatment value of 59.27 ± 92.10 dB with an average gain of 17.65 ± 8.36 dB.

A comparison of the post-treatment gain of PTA in both groups showed better improvement of hearing in a group treated by IT Dex 10 mg/mL compared with 4 mg/mL.

Conclusion

This study demonstrated that IT injection of dexamethasone at a dose of 10 mg/ml was associated with better hearing outcomes compared with 4 mg/mL for the treatment of ISSNHL.

Delivery of therapeutics to the inner ear: The challenge of the blood-labyrinth barrier

Permanent hearing loss affects more than 5% of the world's population, yet there are no nondevice therapies that can protect or restore hearing. Delivery of therapeutics to the cochlea and vestibular system of the inner ear is complicated by their inaccessible location. Drug delivery to the inner ear via the vasculature is an attractive noninvasive strategy, yet the blood-labyrinth barrier at the luminal surface of inner ear capillaries restricts entry of most blood-borne compounds into inner ear tissues. Here, we compare the blood-labyrinth barrier to the blood-brain barrier, discuss invasive intratympanic and intracochlear drug delivery methods, and evaluate noninvasive strategies for drug delivery to the inner ear.

Clinical management and progress in sudden sensorineural hearing loss during pregnancy

Sudden sensorineural hearing loss (SSNHL) is a relatively rare, but distressing, disease in pregnant women. Little is known about the causes, clinical manifestations, treatments, and prognosis of SSNHL. Some hypotheses have been proposed to explain the pathophysiological mechanism of SSNHL, but most of them have not been identified. This article reviews the existing literature to present a summary of this clinical problem. Most patients suffer from SSNHL in the second or third trimester, and show moderate to profound hearing loss. The interval between the initial treatment and onset of hearing loss is less than 10 days in most patients. Some patients with SSNHL show tinnitus, vertigo, or dizziness, and fullness of the ear. Although some patients have a tendency for self-cure, treatment with intravenous dextran 40 combined with intratympanic corticosteroids is probably a safe and effective therapeutic strategy for pregnant patients with SSNHL. Further clinical research is necessary to identify the best therapeutic strategy for these patients.

Prediction of hearing recovery in sudden deafness treated with intratympanic steroids

The present study aims to obtain a probability model allowing prediction of auditory recovery in patients affected by sudden sensorineural hearing loss treated exclusively with intratympanic steroids. A monocentric retrospective chart review of 381 patients has been performed. A Probit model was used to investigate the correlation between the success of treatment (marked or total recovery according to Furuashi’s criteria) and the delay between onset of disease and beginning of therapy. The age of patients and audiometric curve shapes were included in the analysis. The results show that delay is negatively correlated with variable success. Considering the entire sample, each day of delay decreases the probability of success by 3%. The prediction model shows that for each day that passes from the onset of the disease the probability of success declines in absence of the medical treatment, hence we conclude that early treatment is strongly recommended.

Local Drug Delivery for the Treatment of Neurotology Disorders

Neurotology disorders such as vertigo, tinnitus, and hearing loss affect a significant proportion of the population (estimated 39 million in the United States with moderate to severe symptoms). Yet no pharmacological treatments have been developed, in part due to limitations in effective drug delivery to the anatomically protected inner ear compartment. Intratympanic delivery, a minimally invasive injection performed in the office setting, offers a potential direct route of administration. Currently, off-label use of therapeutics approved to treat disorders via systemic administration are being injected intratympanically, mostly in the form of aqueous solutions, but provide variable levels of drug exposure for a limited time requiring repeated injections. Hence, current drug delivery approaches for neurotology disorders are sub-optimal. This review, following a description of pharmacokinetic considerations of the inner ear, explores the merits of novel delivery approaches toward the treatment of neurotology disorders. Methodologies employing local delivery to the inner ear are described, including direct intracochlear delivery as well as intratympanic methods of infusion and injection. Intratympanic injection delivery formulation strategies including hydrogels, polymers and nanoparticulate systems are explored. These approaches represent progress toward more effective delivery options for the clinical treatment of a variety of neurotology disorders.

Glucococorticoid receptor activation exacerbates aminoglycoside-induced damage to the zebrafish lateral line

Aminoglycoside antibiotics have potent antibacterial properties but cause hearing loss in up to 25% of patients. These drugs are commonly administered in patients with high glucocorticoid stress hormone levels and can be combined with exogenous glucocorticoid treatment. However, the interaction of stress and aminoglycoside-induced hearing loss has not been fully explored. In this study, we investigated the effect of the glucocorticoid stress hormone cortisol on hair cells in the zebrafish lateral line as an important step toward understanding how physiological stressors modulate hair cell survival. We found that 24-hr cortisol incubation sensitized hair cells to neomycin damage. Pharmacological and genetic manipulation demonstrates that sensitization depended on the action of the glucocorticoid receptor but not the mineralocorticoid receptor. Blocking endogenous cortisol production reduced hair cell susceptibility to neomycin, further evidence that glucocorticoids modulate aminoglycoside ototoxicity. Glucocorticoid transcriptional activity was apparent in lateral line hair cells, suggesting a direct action of cortisol in these aminoglycoside-sensitive cells. Our work shows that the stress hormone cortisol can increase hair cell sensitivity to aminoglycoside damage, which highlights the importance of recognizing stress and the impacts of glucocorticoid signaling in both ototoxicity research and clinical practice.

Dexamethasone and Dexamethasone Phosphate Entry into Perilymph Compared for Middle Ear Applications in Guinea Pigs

Dexamethasone phosphate is widely used for intratympanic therapy in humans. We assessed the pharmacokinetics of dexamethasone entry into perilymph when administered as a dexamethasone phosphate solution or as a micronized dexamethasone suspension, with and without inclusion of poloxamer gel in the medium. After a 1-h application to guinea pigs, 10 independent samples of perilymph were collected from the lateral semicircular canal of each animal, allowing entry at the round window and stapes to be independently assessed. Both forms of dexamethasone entered the perilymph predominantly at the round window (73%), with a lower proportion entering at the stapes (22%). When normalized by applied concentration, dexamethasone phosphate was found to enter perilymph far more slowly than dexamethasone, in accordance with its calculated lipid solubility and polar surface area properties. Dexamethasone phosphate therefore has a problematic combination of kinetic properties when used for local therapy of the ear. It is relatively impermeable and enters perilymph only slowly from the middle ear. It is then metabolized in the ear to dexamethasone, which is more permeable through tissue boundaries and is rapidly lost from perilymph. Understanding the influence of molecular properties on the distribution of drugs in perilymph provides a new level of understanding which may help optimize drug therapies of the ear.

Intratympanic steroids as a salvage therapy for severe to profound idiopathic sudden sensorineural hearing loss

BACKGROUND

Idiopathic sudden sensorineural hearing loss (ISSNHL) is defined as a decline in hearing affecting three or more frequencies by 30 dB Objective: The aim of this study was to evaluate the results of intratympanic steroids as a salvage treatment for severe ISSNHL.

MATERIALS AND METHODS

A regimen of three IT steroid injections was offered to patients who failed a 7-days intravenous steroid treatment. Eighty-four patients underwent IT salvage treatment (IT group). Their outcomes were compared with those of 255 patients with severe ISSNHL who received the same intravenous steroid regimen without salvage IT steroid therapy (Control group).

RESULTS

56% of the patients in the IT group had a hearing improvement of >15 dB after one month. The average hearing improvements were 26.5 ± 28 dB and 27.9 ± 24 dB in the IT group and the Control group, respectively (p = .67). However, patients with a type E audiogram pattern (total deafness), displayed a substantial hearing gain.

CONCLUSION

Intratympanic steroids failed to show a global auditory benefit as a salvage treatment in patients with severe ISSNHL.

SIGNIFICANCE

Our data suggest that a salvage treatment with intratympanic dexamethasone may be offered to patients with total deafness for whom the first systemic treatment has failed.

Intratympanic methylprednisolone administration promotes the recovery of idiopathic sudden sensorineural hearing loss: a retrospective case-control study

BACKGROUND

Efficacy of current treatment methods in idiopathic sudden sensorineural hearing loss (ISSNHL) is still unsatisfactory.

OBJECTIVE

This study aimed to discover in differences in effect between steroid applications responsible for promoting the prognosis in ISSNHL.

MATERIALS AND METHODS

A study was conducted to diagnose ISSNHL patients in our hospital from January 2014 to September 2016. All patients accepted treatments including intravenous injection (intravenous dexamethasone, [IV DXM]), intratympanic injection (intratympanic methylprednisolone [IT MP], intratympanic dexamethasone [IT DXM]) or combined injections with steroids (IV + IT DXM). Patients were divided into groups according to treatment outcomes and clinical characteristics of each group were compared for univariate comparison. Logistic regression was utilized to verify screening factors from univariate comparison for exclude biases.

RESULTS

There were 313 patients with ISSNHL enrolled in the study. Logistic regression verified that vertigo (p = .023), severity of hearing loss (p=.969), pattern of hearing loss (p = .03), and the treatment method (p < .001) were statistically related to the patients' prognosis based on the condition all biases had been excluded as possible. IT MP showed a better prognosis of hearing improvement compared to treatment with IT DXM (OR = 0.5), IV DXM (OR =0.226), and IV DXM + IV DXM (OR = 0.320).

CONCLUSIONS AND SIGNIFICANCE

IT MP treatment could be utilized as initial treatment in ISSNHL and might promote outcomes.

Controlled drug release to the inner ear: Concepts, materials, mechanisms, and performance

Progress in drug delivery to the ear has been achieved over the last few years. This review illustrates the main mechanisms of controlled drug release and the resulting geometry- and size-dependent release kinetics. The potency, physicochemical properties, and stability of the drug molecules are key parameters for designing the most suitable drug delivery system. The most important drug delivery systems for the inner ear include solid foams, hydrogels, and different nanoscale drug delivery systems (e.g., nanoparticles, liposomes, lipid nanocapsules, polymersomes). Their main characteristics (i.e., general structure and materials) are discussed, with special attention given to underlining the link between the physicochemical properties (e.g., surface areas, glass transition temperature, microviscosity, size, and shape) and release kinetics. An appropriate characterization of the drug, the excipients used, and the formulated drug delivery systems is necessary to achieve a deeper understanding of the release process and decrease variability originating from the drug delivery system. This task cannot be solved by otologists alone. The interdisciplinary cooperation between otology/neurotology, pharmaceutics, physics, and other disciplines will result in improved drug delivery systems for the inner ear.

A Surgical Procedure for the Administration of Drugs to the Inner Ear in a Non-Human Primate Common Marmoset (Callithrix jacchus)

Hearing research has long been facilitated by rodent models, although in some diseases, human symptoms cannot be recapitulated. The common marmoset (Callithrix jacchus) is a small, easy-to-handle New World monkey which has a similar anatomy of the temporal bone, including the middle ear ossicular chains and inner ear to humans, than in comparison with that of rodents. Here, we report a reproducible, safe, and rational surgical approach to the cochlear round window niche for the drug delivery to the inner ear of the common marmoset. We adopted posterior tympanotomy, a procedure used clinically in human surgery, to avoid manipulation of the tympanic membrane that may cause conductive hearing loss. This surgical procedure did not lead to any significant hearing loss. This approach was possible due to the large bulla structure of the common marmoset, although the lateral semicircular canal and vertical portion of the facial nerve should be carefully considered. This surgical method allows us to perform the safe and accurate administration of drugs without hearing loss, which is of great importance in obtaining pre-clinical proof of concept for translational research.

Current concepts in the management of idiopathic sudden sensorineural hearing loss

PURPOSE OF REVIEW

The purpose of this manuscript is to review the initial management strategies for idiopathic sudden sensorineural hearing loss, with an emphasis on the role that steroids play in treatment of this condition, and discuss options for auditory rehabilitation of persistent unilateral hearing loss.

RECENT FINDINGS

Recent data suggest that hearing improvement may be greater for patients initially treated with both systemic and intratympanic steroid when compared with those treated with systemic steroids alone. Salvage intratympanic steroids have been shown to confer hearing benefit if initial management fails. The ideal dosing regimen for intratympanic steroids has not been established, but evidence supports that higher dosing strategies are advantageous. Cochlear implantation has emerged as a strategy for auditory rehabilitation of persistent unilateral hearing loss. Recent studies have demonstrated high patient satisfaction, subjective improvement in tinnitus, and objective performance benefit after cochlear implantation for single-sided deafness.

SUMMARY

Patients can be offered steroid therapy in the initial management of idiopathic sudden sensorineural hearing loss, but should be counseled that the efficacy of steroids remains unclear. If patients fail to improve with initial management, salvage intratympanic steroid administration should be considered. If hearing loss persists long term, options for auditory rehabilitation should be discussed.

The role of explorative tympanotomy in patients with sudden sensorineural hearing loss with and without perilymphatic fistula

PURPOSE

The purpose of this study was to describe the role of explorative tympanotomy in patients with Profound Sudden Sensorineural Hearing Loss (SSNHL) without clinical evidence of perilymphatic or labyrinthine fistula and to compare intraoperative findings with the postoperative hearing outcome.

STUDY DESIGN

Retrospective study of all patients diagnosed with SSNHL who underwent explorative tympanotomy between 2002 and 2005.

SETTINGS

Tertiary care university-affiliated hospital.

SUBJECTS AND METHODS

Eighty-two patients were diagnosed with unilateral profound SSNHL and underwent tympanotomy with sealing of the round and oval windows. Values of pure tone audiograms and percentage hearing loss of patients with and without intraoperative diagnosed perilymphatic fistula (PLF) were compared and analyzed.

RESULTS

PLF was diagnosed in 28% cases intraoperatively. In most cases, hearing improved significantly after surgery. Interestingly, patients with PLF had a 2.4 times greater decrease of percentage hearing loss compared to patients without PLF.

CONCLUSIONS

Explorative tympanotomy seems to be useful in patients with profound SSNHL. Patients with PLF benefit more from the surgical procedure and have better outcome than patients without PLF.

Local inner ear application of dexamethasone in cochlear implant models is safe for auditory neurons and increases the neuroprotective effect of chronic electrical stimulation

Dexamethasone (DEX) can reduce fibrous tissue growth as well as loss of residual hearing which may occur after cochlear implantation. Little is known about the effect of local inner ear DEX treatment on the spiral ganglion neurons (SGN), which are the target of the electrical stimulation with a cochlear implant (CI). Three different clinically relevant strategies of DEX-delivery into the inner ear were used. DEX was either eluted from the electrode carriers' silicone, released from a reservoir by passive diffusion, or actively applied using a pump based system. The effect of the locally applied DEX on SGN density, size and function was evaluated. DEX did not affect the SGN density compared to the relevant control groups. Simultaneously applied with chronic electrical stimulation (ES), DEX increased the neuroprotective effect of ES in the basal region and the hearing threshold tended to decrease. The EABR thresholds did not correlate with the relevant SGN density. When correlating the SGN number with fibrosis, no dependency was observed. DEX concentrations as applied in these animal models are safe for inner ear delivery in terms of their effect on SGN density. Additionally, DEX tends to improve the neuroprotective effect of chronic electrical stimulation by increasing the number of surviving neurons. This is an important finding in regard to clinical applications of DEX for local treatment of the inner ear in view of cochlear implantation and other applications.

Intracochlear drug delivery in combination with cochlear implants : Current aspects

Local drug application to the inner ear offers a number of advantages over systemic delivery. Local drug therapy currently encompasses extracochlear administration (i. e., through intratympanic injection), intracochlear administration (particularly for gene and stem cell therapy), as well as various combinations with auditory neurosensory prostheses, either evaluated in preclinical or clinical studies, or off-label. To improve rehabilitation with cochlear implants (CI), one focus is the development of drug-releasing electrode carriers, e. g., for delivery of glucocorticosteroids, antiapoptotic substances, or neurotrophins to the inner ear. The performance of cochlear implants may thus be improved by protecting neuronal structures from insertion trauma, reducing fibrosis in the inner ear, and by stimulating growth of neuronal structures in the direction of the electrodes. Controlled drug release after extracochlear or intracochlear application in conjunction with a CI can also be achieved by use of a biocompatible, resorbable controlled-release drug-delivery system. Two case reports for intracochlear controlled release drug delivery in combination with cochlear implants are presented. In order to treat progressive reduction in speech discrimination and increased impedance, two cochlear implant patients successfully underwent intracochlear placement of a biocompatible, resorbable drug-delivery system for controlled release of dexamethasone. The drug levels reached in inner ear fluids after different types of local drug application strategies can be calculated using a computer model. The intracochlear drug concentrations calculated in this way were compared for different dexamethasone application strategies.

Hearing Changes After Intratympanically Applied Steroids for Primary Therapy of Sudden Hearing Loss: A Meta-analysis Using Mathematical Simulations of Drug Delivery Protocols

OBJECTIVE

Controlled and uncontrolled studies with primary intratympanic or combined intratympanic and systemic application of glucocorticosteroids for idiopathic sudden hearing loss were analyzed by means of a meta-analysis in an attempt to establish optimal local drug delivery protocols.

STUDY DESIGN

A total of 25 studies with 28 treatment groups between January 2000 and June 2014 were selected that adequately described drug delivery protocols. Cochlear drug levels were calculated by a validated computer model of drug dispersion in the inner ear fluids based on the concentration and volume of glucocorticoids applied, the time the drug remained in the middle ear, and the specific timing of injections. Various factors were compared with hearing outcome, including baseline data, individual parameters of the application protocols, calculated peak concentration (Cmax), and total dose (area under the curve).

RESULTS

There was no dependence of hearing outcome on individual parameters of the application protocol, Cmax, or area under the curve. Final hearing threshold was notably independent of delay of treatment.

CONCLUSION

During primary intratympanic or combined steroid therapy of idiopathic sudden hearing loss, the tendency toward early treatment having a positive effect on hearing improvement is thought to be a "sham effect," likely related to spontaneous recovery. Change in pure-tone average may not be an adequate outcome parameter to assess effectiveness of the intervention, as it depends on the degree of initial hearing loss. Final pure-tone average provides a better alternative.

Intratympanic steroid delivery by an indwelling catheter in refractory severe sudden sensorineural hearing loss

OBJECTIVE

Many studies over the last decade showed favorable outcomes with intratympanic (IT) steroid treatment, alone as salvage treatment or in combination with conventional systemic therapy (ST). However, in severe to profound sensorineural hearing loss resistant to ST, the optimal infusion mode, the type and concentration of the solution, the preferable drug, its total amount, and the duration and fractionation of the treatment are still debated. Aim of the study was to investigate the feasibility and the outcomes of a direct and constant IT delivery of dexamethasone (DEX) by means of a new indwelling catheter.

METHODS

A prospective case-control study in a tertiary referral university hospital. Ninety-nine subjects treated with ST only and 28 with additional IT DEX have been included in the study. A 4 Fr catheter inserted in a sub-annular fashion with a minimal postero-inferior tympanotomy through and endocanalar approach under local anesthesia. DEX 4mg/ml delivered daily, up to 7 days. Daily bone and air-conducted pure tone and speech audiometry were performed with a follow-up at 1, 3, 6 months after treatment.

RESULTS

Twenty-one out of 28 patients (75%) refractory to ST gained on average 24.0dB±20.5dB HL after IT-DEX, compared to 35.4% (average 6.7dB±16.6dB HL) of those receiving only medical ST (p<0.001). No significant side effects were noted.

CONCLUSION

In severe to profound sudden deafness refractory to conventional ST, the daily perfusion of 4mg/ml DEX through an intratympanic catheter is an easy, well accepted procedure that enables patients to receive a drug in the middle ear in a repeatable or sustained form, with minimal discomfort and a partial rescue (67.86%) and a speech recognition gain of 39%.

Predictors of hearing recovery in patients with severe sudden sensorineural hearing loss

Background

Sudden sensorineural hearing loss (SSHL) is a disease, which severely affects the patient’s social and relational life. The underlying pathomechanisms have not been finally clarified yet and outcome is not predictable.

Methods

We conducted a retrospective study in order to identify parameters that influence hearing recovery. The data base contains results of basic otoneurological tests and clinical parameters of 198 patients with idiopathic SSHL of at least 60 dB in at least four frequencies, diagnosed and treated at the University Hospital of Münster, Germany, between 1999 and 2015. Hearing recovery was measured by pure tone audiometry.

Results

Multivariate linear and logistic regression analyses indicate that the chance as well as the magnitude of hearing recovery is higher for patients with normal caloric testing than for patients with pathological caloric testing. However, for the subgroup of patients who attained a hearing recovery, the caloric testing result was not found to influence the magnitude. Instead, the magnitude was noticeably lower for patients within this subgroup who had a previous hearing loss. Furthermore, we found indications that the magnitude is higher for men than for women and that receiving a high-dose steroid therapy is associated with a higher chance and magnitude of a hearing recovery.

Conclusions

We conclude that SSHL associated with disorders of the vestibular system or previous hearing loss represent special sub-entities of SSHL that may be caused by unique pathophysiological mechanisms and are associated with worse outcome. Furthermore, our data support the importance of elevated dosage of steroids in SSHL therapy.

A software tool for pure‑tone audiometry. Classification of audiograms for inclusion of patients in clinical trials. English version

Objective

Selecting subjects for clinical trials on hearing loss therapies relies on the patient meeting the audiological inclusion criteria. In studies on the treatment of idiopathic sudden sensorineural hearing loss, the patient’s acute audiogram is usually compared with a previous audiogram, the audiogram of the non-affected ear, or a normal audiogram according to an ISO standard. Generally, many more patients are screened than actually fulfill the particular inclusion criteria. The inclusion criteria often require a calculation of pure-tone averages, selection of the most affected frequencies, and calculation of hearing loss differences.

Materials and methods

A software tool was developed to simplify and accelerate this inclusion procedure for investigators to estimate the possible recruitment rate during the planning phase of a clinical trial and during the actual study. This tool is Microsoft Excel-based and easy to modify to meet the particular inclusion criteria of a specific clinical trial. The tool was retrospectively evaluated on 100 patients with acute hearing loss comparing the times for classifying automatically and manually. The study sample comprised 100 patients with idiopathic sudden sensorineural hearing loss.

Results and conclusion

The age- and sex-related normative audiogram was calculated automatically by the tool and the hearing impairment was graded. The estimated recruitment rate of our sample was quickly calculated. Information about meeting the inclusion criteria was provided instantaneously. A significant reduction of 30 % in the time required for classifying (30 s per patient) was observed.

Supplementary file

Additional material to this article (Rahne_InclusionCriteria_v.en2.1.xlsx) will be available online at 10.1007/s00106-015-0089-3

Effects of sustained release dexamethasone hydrogels in hearing preservation cochlear implantation

It has been shown that glucocorticoids reduce the hearing threshold shifts associated with cochlear implantation. Previous studies evaluated the administration of glucocorticoids immediately before surgery or the repeated pre- or perioperative systemic application of glucocorticoids. The aim of this study was to evaluate the effects of a sustained release dexamethasone hydrogel in hearing preservation cochlear implantation. To address this issue, a guinea pig model of cochlear implantation was used. 30 normal hearing pigmented guinea pigs were randomized into a group receiving a single dose of a dexamethasone/poloxamer407 hydrogel one day prior to surgery, a second group receiving the hydrogel seven days prior to surgery and a control group. A silicone cochlear implant electrode designed for the use in guinea pigs was inserted to a depth of 5 mm through a cochleostomy. Compound action potentials of the auditory nerve (frequency range 0.5-32 kHz) were measured preoperatively, directly postoperatively and on postoperative days 3, 7, 14, 21 and 28. Following the last audiometry, temporal bones were harvested and histologically evaluated. Dexamethasone hydrogel application one day prior to surgery resulted in significantly reduced hearing threshold shifts at low, middle and high frequencies measured at postoperative day 28 (p < 0.05). Application of the hydrogel seven days prior to surgery did not show such an effect. Dexamethasone application one day prior to surgery resulted in increased outer hair cell counts in the cochlear apex and in reduced spiral ganglion cell counts in the basal and middle turn of the cochlea, a finding that was associated with a higher rate of electrode translocation in this group. In this study, we were able to demonstrate functional benefits of a single preoperative intratympanic application of a sustained release dexamethasone hydrogel in a guinea pig model of cochlear implantation.

Sustained Inner Ear Steroid Delivery via Bioabsorbable Stent

Objective

To determine the feasibility and tolerability of a steroid-eluting middle ear device on an animal model.

Study Design

Prospective experimental.

Setting

Experimental animal study.

Subjects and Method

Mometasone furoate (MF)–eluting miniature sticks were implanted through a myringotomy incision into the middle ear of 10 guinea pigs. Two additional ears of 2 animals served as controls. Fourteen days after implantation, perilymphatic fluid was collected through an endaural cochleostomy. MF concentrations were measured with high-performance liquid chromatography, and the middle ear mucosal inflammation was graded with hematoxylin and eosin colorations.

Results

Fourteen days after implantation, all tympanic membranes had fully healed. An average of 165 ng/mL of MF was detected in the perilymphatic fluid of the experimental ears, and none was measured in control ears. Microscopic residues of the ministicks were found in 90% of the samples, confirming the bioabsorbable properties of this device. Histologic analysis of the middle ear mucosa found similar inflammation profiles in both groups, thereby suggesting middle ear tolerability.

Conclusion

MF-coated bioabsorbable miniature stick allows for prolonged delivery over 14 days without injuring the middle ear mucosa. Middle ear–sustained steroid delivery may prove to be beneficial in numerous neurotologic conditions.

Intratympanic dexamethasone injection vs methylprednisolone for the treatment of refractory sudden sensorineural hearing loss

Background:

During the past years various drugs have been used for sudden sensorineural hearing loss (SSNHL) treatment including steroids that are shown to be beneficial. Directed delivery of high doses of steroids into the inner ear is suggested for its potential and known as intratympanic steroids therapy (IST). Despite the use of dexamethasone and methylprednisolone as the traditional treatments, there are still debates about the optimal dosage, preferred drug, and the route of administration.

Materials and Methods:

We performed a randomized clinical trial study in which 50 patients suffering from SSNHL and resistant to standard therapy were employed. Each patient took 0.5 ml methylprednisolone (40 mg/mg) along with bicarbonate or dexamethasone (4 mg/mL) through direct intratympanic injection. This method was performed and scheduled once every 2 days for three times only for the dexamethasone receiving group. Hearing test was carried out and the results were analyzed according to a four-frequency (0.5, 1.0, 2.0, 3.0 kHz) pure tone average (PTA) and Siegel's criteria.

Results:

According to Siegel's criteria, three out of 25 (12%) dexamethasone receiving patients were healed in 1 and 4 (16%), 9 (32%) were respectively recovered in Siegel's criteria 2, 3, and 9 (32%) showed no recovery. In the group receiving methylprednisolone, recovery was found in 6 (24%), 8 (32%), 7 (28%) patients in the Siegel's criteria 1, 2, 3, respectively, and in 4 (16%) patients no recovery was recorded. In methylprednisolone group, hearing was significantly improved compared to the dexamethasone group (P < 0.05). The general hearing improvement rate was 84% in methylprednisolone receiving patients showing a significantly higher improvement than 64% in the dexamethasone group.

Conclusions:

Topical intratympanic treatment with methylprednisolone is safe and an effective treatment approach for those SSNHL cases that are refractory to the common therapies by Dexamethasone.