Use of Gases to Treat Cochlear Conditions

Biomaterials as a new option for treating sensorineural hearing loss

Sensorineural hearing loss (SNHL) usually involves damage to complex auditory pathways such as inner ear cells and auditory nerves. The highly intricate and nuanced characteristics of these cells render their repair and regeneration extremely challenging, making it difficult to restore hearing to normal levels once it has been compromised. The effectiveness of traditional drugs is so minimal that they provide little help with the treatment. Fortunately, extensive experiments have demonstrated that combining biomaterials with conventional techniques significantly enhances drug effectiveness. This article reviews the research progress of biomaterials in protecting hair cells and the auditory nerve, repairing genes related to hearing, and developing artificial cochlear materials. By organizing the knowledge presented in this article, perhaps new insights can be provided for the clinical management of SNHL.

Space Station-like Composite Nanoparticles for Co-Delivery of Multiple Natural Compounds from Chinese Medicine and Hydrogen in Combating Sensorineural Hearing Loss

Ototoxic drugs such as aminoglycoside antibiotics and cisplatin (CDDP) can cause sensorineural hearing loss (SNHL), which is closely related to oxidative stress and the acidification of the inner ear microenvironment. Effective treatment of SNHL often requires multifaceted approach due to the complex pathology, and drug combination therapy is expected to be at the forefront of modern hearing loss treatment. Here, space-station-like composite nanoparticles (CCC@mPP NPs) with pH/oxidation dual responsiveness and multidrug simultaneous delivery capability were constructed and then loaded with various drugs including panax notoginseng saponins (PNS), tanshinone IIA (TSIIA), and ammonia borane (AB) to provide robust protection against SNHL. Molecular dynamics simulation revealed that carboxymethyl chitosan/calcium carbonate-chitosan (CCC) NPs and monomethoxy poly(ethylene glycol)-PLGA (mPP) NPs can rendezvous and dock primarily by hydrogen bonding, and electrostatic forces may be involved. Moreover, CCC@mPP NPs crossed the round window membrane (RWM) and entered the inner ear through endocytosis and paracellular pathway. The docking state was basically maintained during this process, which created favorable conditions for multidrug delivery. This nanosystem was highly sensitive to pH and reactive oxygen species (ROS) changes, as evidenced by the restricted release of payload at alkaline condition (pH 7.4) without ROS, while significantly promoting the release in acidic condition (pH 5.0 and 6.0) with ROS. TSIIA/PNS/AB-loaded CCC@mPP NPs almost completely preserved the hair cells and remained the hearing threshold shift within normal limits in aminoglycoside- or CDDP-treated guinea pigs. Further experiments demonstrated that the protective mechanisms of TSIIA/PNS/AB-loaded CCC@mPP NPs involved direct and indirect scavenging of excessive ROS, and reduced release of pro-inflammatory cytokines. Both in vitro and in vivo experiments showed the high biocompatibility of the composite NPs, even after long-term administration. Collectively, this work suggests that composite NPs is an ideal multi-drug-delivery vehicle and open new avenues for inner ear disease therapies.

[Hyperbaric oxygen therapy : Selected indications in the discipline of otorhinolaryngology]

Hyperbaric oxygenation (HBO) represents the controlled exposure to positive pressure with simultaneous inhalation of pure oxygen. It is considered to be an effective treatment option for diseases with restricted blood flow as oxygen not only binds chemically to hemoglobin but also physically dissolves in blood plasma. With the help of a hyperbaric chamber the ambient pressure of a patient can be modified and the physiological characteristics in positive pressure can be medically used. The indications relevant to otorhinolaryngology are necrotizing otitis externa and skull base osteomyelitis, other forms of osteomyelitis, gangrene, wound healing disorders and sudden loss of hearing. When choosing a treatment, not only the availability and costs of HBO treatment play a role but also the patient's tolerance of overpressure. The risks of treatment, e.g., due to oxygen toxicity or barotrauma of the middle ear or the paranasal sinuses, must be weighed up against the potential benefits.

Hydrogen Gas Inhalation Attenuates Acute Impulse Noise Trauma: A Preclinical In Vivo Study

OBJECTIVE

Molecular hydrogen (H₂) has shown therapeutic potential in several oxidative stress-related conditions in humans, is well-tolerated, and is easily administered via inhalation.The aim of this preclinical in vivo study was to investigate whether impulse noise trauma can be prevented by H₂ when inhaled immediately after impulse noise exposure.

METHODS

Guinea pigs (n = 26) were subjected to impulse noise (n = 400; 156 dB SPL; 0.33/s; n = 11; the Noise group), to impulse noise immediately followed by H₂ inhalation (2 mol%; 500 ml/min; 1 hour; n = 10; the Noise + H₂ group), or to H₂ inhalation (n = 5; the H₂ group). The acoustically evoked ABR threshold at 3.15, 6.30, 12.5, 20.0, and 30.0 kHz was assessed before and 4 days after impulse noise and/or H₂ exposure. The cochleae were harvested after the final ABR assessment for quantification of hair cells.

RESULTS

Noise exposure caused ABR threshold elevations at all frequencies (median 35, 35, 30, 35, and 35 dB SPL, the Noise group; 20, 25, 10, 13, and 20 dB SPL, the Noise + H₂ group; P < .05) but significantly less so in the Noise + H₂ group (P < .05). Outer hair cell (OHC) loss was in the apical, mid, and basal regions 8.8%, 53%, and 14% in the Noise group and 3.5%, 22%, and 1.2% in the Noise + H₂ group. The corresponding inner hair cell (IHC) loss was 0.1%, 14%, and 3.5% in the Noise group and 0%, 2.8%, and 0% in the Noise + H₂ group. The difference between the groups was significant in the basal region for OHCs (P = .003) and apical (P = .033) and basal (P = .048) regions for IHCs.

CONCLUSIONS

Acute acoustic trauma can be reduced by H₂ when inhaled immediately after impulse noise exposure.

Combined Acupuncture-Hyperbaric Oxygen-Steroids Therapy for Idiopathic Sudden Sensorineural Hearing Loss: A Retrospective Observational Study

Objectives: Acupuncture, widely used in Chinese society, has been studied as an adjunct treatment of idiopathic sudden sensorineural hearing loss (ISSNHL). The purpose of this study is to investigate the effectiveness of combined acupuncture and hyperbaric oxygen therapy (HBOT) with conventional steroid therapy for ISSNHL. Methods: This retrospective chart review enrolled 154 patients who met the ISSNHL criteria and were categorized into three groups according to the different treatment regimens. Among these patients, 43 underwent steroid therapy only (S) group, 74 received steroid and HBOT (S-H) group, and the remaining 37 were treated with combined acupuncture-HBOT in addition to steroid therapy (S-H-A) group. The outcome was determined by comparing the differences in pure-tone thresholds and absolute hearing gains after treatment calculated at each audiometric octave frequency or grouped frequencies of audiograms. Hearing recoveries classified into three grades: complete, partial, and poor were also analyzed and compared among different treatment groups. Results: All subjects presented with initial severe hearing loss with averaged hearing thresholds >70 dB. The S-H-A group exhibited good hearing improvement outcomes at each audiometric octave frequency and grouped frequencies of audiograms, with greater hearing gain and had more favorable outcomes in hearing recovery grades compared with the S group and the S-H group. Conclusions: The results obtained in this study revealed a preliminary finding of ISSNHL patients benefiting from combined acupuncture, HBOT, and conventional steroid therapy. Acupuncture is a safe and nonpharmacologic treatment option and can be considered as an initial treatment strategy in such a clinical scenario.

Management of tympanic membrane retractions: a systematic review

Importance

Tympanic membrane retraction (TMR) is a relatively common otological finding. However, no consensus on its management exists. We are looking especially for a treatment strategy in the military population who are unable to attend frequent follow-up visits, and who experience relatively more barotrauma at great heights and depths and easily suffer from otitis externa from less hygienic circumstances.

Objective

To assess and summarize the available evidence for the effectiveness of surgical interventions and watchful waiting policy in patients with a tympanic membrane retraction.

Evidence review

The protocol for this systematic review was published at Prospero (207859). PubMed, Embase, and the Cochrane Database of Systematic Reviews were systematically searched from inception up to September 2020 for published and unpublished studies. We included randomized trials and observational studies that investigated surgical interventions (tympanoplasty, ventilation tube insertion) and wait-and-see policy. The primary outcomes of this study were clinical remission of the tympanic membrane retraction, tympanic membrane perforations and cholesteatoma development.

Findings

In total, 27 studies were included, consisting of 1566 patients with TMRs. We included data from 2 randomized controlled trials (76 patients) and 25 observational studies (1490 patients). Seven studies (329 patients) investigated excision of the TMR with and without ventilation tube placement, 3 studies (207 patients) investigated the wait-and-see policy and 17 studies (1030 patients) investigated tympanoplasty for the treatment of TMRs.

Conclusions and relevance

This study provides all the studies that have been published on the surgical management and wait-and-policy for tympanic membrane retractions. No high level of evidence comparative studies has been performed. The evidence for the management of tympanic membrane retractions is heterogenous and depends on many factors such as the patient population, location and severity of the TMR and presence of other ear pathologies (e.g., perforation, risk of cholesteatoma and serous otitis media).

Supplementary Information

The online version contains supplementary material available at 10.1007/s00405-021-06719-3.