Tinnitus: Evaluation of Intratympanic Injection of Combined Lidocaine and Corticosteroids

Easing the Burden of Tinnitus: A Narrative Review for Exploring Effective Pharmacological Strategies

Many individuals seek medical attention for tinnitus, desiring relief from the distress caused by the condition; however, the treatment process is far from straightforward. The most effective treatments for chronic subjective tinnitus, such as tinnitus retraining therapy (TRT) and cognitive behavioral therapy (CBT), require considerable time and efforts. As a result, many of them express a desire for alleviation through medication. While it is true that medication is not generally recommended in treatment guidelines for chronic subjective tinnitus, in specific situations such as when accompanied by symptoms of depression or anxiety-drugs like antidepressants or anxiolytics may have a meaningful impact on symptom reduction. Additionally, medication can prove effective in certain specialized forms of tinnitus, such as typewriter tinnitus, as opposed to chronic subjective tinnitus. Although intratympanic dexamethasone injections for tinnitus have been reported to lack efficacy compared to a placebo, if patients perceive subjective satisfaction due to a placebo effect, it holds significance. From the perspective of patients suffering from tinnitus, even if the therapeutic mechanism is set aside, experiencing some degree of relief through certain medications can enhance compliance with evidence-based treatments like TRT and CBT.

Current and Emerging Therapies for Chronic Subjective Tinnitus

IMPORTANCE

Chronic subjective tinnitus, the perception of sound without an external source for longer than six months, may be a greatly debilitating condition for some people, and is associated with psychiatric comorbidities and high healthcare costs. Current treatments are not beneficial for all patients and there is a large need for new therapies for tinnitus.

OBSERVATIONS

Unlike rarer cases of objective tinnitus, chronic subjective tinnitus often has no obvious etiology and a diverse pathophysiology. In the absence of objective testing, diagnosis is heavily based on clinical assessment. Management strategies include hearing aids, sound masking, tinnitus retraining therapy, cognitive behavioral therapy, and emerging therapies including transcranial magnetic stimulation and electrical stimulation.

CONCLUSIONS AND RELEVANCE

Although current treatments are limited, emerging diagnostics and treatments provide promising avenues for the management of tinnitus symptoms.

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.

Effectiveness of Intratympanic Dexamethasone Injection for Tinnitus Treatment: A Systematic Review and Meta-Analysis

Objectives

Intratympanic dexamethasone injection (ITDI) has been introduced as a treatment option for subjective tinnitus. However, the effects of ITDI on patients with tinnitus remain unclear. In the present systematic review and metaanalysis, we evaluated the effectiveness of ITDI for tinnitus treatment.

Methods

We searched Medline, the Cochrane Central Register of Controlled Trials, and Embase. Four double-blind randomized controlled trials that tested the efficacy of ITDI compared with a placebo were deemed eligible for a quantitative meta-analysis, while four prospective studies and seven retrospective studies reporting the effectiveness of ITDI on tinnitus treatment were included in a qualitative synthesis.

Results

In the four studies included in the quantitative meta-analysis, ITDI did not show evidence of tinnitus improvement compared with placebo (odds ratio [OR], 1.38; 95% confidence interval, 0.53-3.61). In the 11 studies included in the qualitative synthesis, seven retrospective studies without controls reported rates of tinnitus improvement after ITDI ranging from 35.9% to 91.3%. In the four prospective studies with controls, ITDI seemed to be effective when combined with other drugs for tinnitus treatment.

Conclusion

ITDI alone did not show a significant effect for treating tinnitus compared with placebo. However, the potential of combination treatment of ITDI with other drugs for tinnitus therapy should be further studied in more systematic research.

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.

Methodological Aspects of Randomized Controlled Trials for Tinnitus: A Systematic Review and How a Decision Support System Could Overcome Barriers

Although a wide range of tinnitus management interventions is currently under research and a variety of therapeutic interventions have already been applied in clinical practice, no optimal and universal tinnitus treatment has been reached yet. This fact is to some extent a consequence of the high heterogeneity of the methodologies used in tinnitus related clinical studies. In this manuscript, we have identified, summarized, and critically appraised tinnitus-related randomized clinical trials since 2010, aiming at systematically mapping the research conducted in this area. The results of our analysis of the 73 included randomized clinical trials provide important insight on the identification of limitations of previous works, methodological pitfalls or gaps in current knowledge, a prerequisite for the adequate interpretation of current literature and execution of future studies.

Transcutaneous Electrical Nerve Stimulation for Treatment of Tinnitus: A Systematic Review and Meta-analysis

OBJECTIVE

To evaluate the treatment efficacy of transcutaneous electrical nerve stimulation (TENS) in patients with tinnitus.

DATA SOURCES

PubMed, Scopus, Web of Science, and Cochrane Library were searched for the following concepts: "Transcutaneous Electric Nerve Stimulation" and "Tinnitus."

STUDY SELECTION

Inclusion: 1) double- or single-blinded randomized controlled trials; 2) double- or single-blinded randomized comparison trials; 3) prospective or retrospective observational studies; and 4) case series. Exclusion: Non-English studies, nonhuman studies, case reports (n ≤ 5), and review articles.

DATA EXTRACTION

Tinnitus Handicap Inventory (THI), the Visual Analog Scale (VAS), and perceived tinnitus suppression after treatment. Additional data collected included tinnitus laterality, duration of symptoms, location of electrode placement, time to follow-up, etiology of tinnitus, and treatment side effects.

DATA SYNTHESIS

The literature search yielded 2941 unique articles. After reviewing 118 full-text articles, 17 studies reporting on 1,215 patients were included for final analysis. Four studies provided data available for meta-analysis of pre- and posttreatment THI and VAS (Cochrane Review Manager). TENS showed significant overall reduction on THI (-7.55 [-10.93 to -4.18], p < 0.0001) and VAS (-0.65 [-0.99 to -0.30], p < 0.0002). Subjective improvement of tinnitus was pooled across 13 studies using meta-analysis of proportions (MedCalc). Tinnitus suppression occurred in 40.0% [28.9-51.7%] patients. Among those who responded, 22.2% [12.2-29.7%] experienced complete suppression and 10.2% [0.2-31.9%] experienced persistent improvement at 3 months.

CONCLUSIONS

TENS represents a safe and feasible treatment option for tinnitus and might be a worthy consideration among the spectrum of interventions developed for tinnitus.

Tinnitus Perspectives among Israeli Ear, Nose and Throat Physicians: A Nationwide Survey

OBJECTIVES

To study the compliance of ear, nose, and throat (ENT) physicians to the American Association Otolaryngology-Head - Neck Surgery (AAO-HNS) clinical practice guidelines (CPG) for tinnitus and to identify the disparity of both diagnosis and management options in the absence of a local protocol for the management of adult tinnitus.

MATERIALS AND METHODS

A voluntary and anonymous questionnaire was emailed in a Google spread-out sheet format to all practicing ENT physicians across the country (n=370). Overall, 126 ENT physicians responded to the questionnaire (34% of the physicians to whom the questionnaire was sent).

RESULTS

Medical history focuses on tinnitus characteristics and otological signs, and symptoms are often queried (80%-98%). Physicians routinely perform an otoscopic examination, whereas other relevant possible physical findings, such as temporomandibular joint disorders or neck trauma, are less frequently examined. Treating physicians have the most frequent recourse to sound therapy and cognitive behavioral therapy in accordance with AAO-HNS CPG.

CONCLUSION

The publication of the AAO-HNS CPG for tinnitus is important, permitting a common approach for the diagnosis and management of primary tinnitus (PT). A diagnosis and management scheme that takes into consideration both the AAO-HNS CPG for tinnitus as well as physician diagnosis and management paradigms is suggested.

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.