Magnetic Stimulation Allows Focal Activation of the Mouse Cochlea

Cochlear implants (CIs) strive to restore hearing to those with severe to profound hearing loss by artificially stimulating the auditory nerve. While most CI users can understand speech in a quiet environment, hearing that utilizes complex neural coding (e.g., appreciating music) has proved elusive, probably because of the inability of CIs to create narrow regions of spectral activation. Several novel approaches have recently shown promise for improving spatial selectivity, but substantial design differences from conventional CIs will necessitate much additional safety testing before clinical viability is established. Outside the cochlea, magnetic stimulation from small coils (micro-coils) has been shown to confine activation more narrowly than that from conventional micro-electrodes, raising the possibility that coil-based stimulation of the cochlea could improve the spectral resolution of CIs. To explore this, we delivered magnetic stimulation from micro-coils to multiple locations of the cochlea and measured the spread of activation utilizing a multi-electrode array inserted into the inferior colliculus; responses to magnetic stimulation were compared to analogous experiments with conventional micro-electrodes as well as to the responses to auditory monotones. Encouragingly, the extent of activation with micro-coils was ~60% narrower than that from electric stimulation and largely similar to the spread arising from acoustic stimulation. The dynamic range of coils was more than three times larger than that of electrodes, further supporting a smaller spread of activation. While much additional testing is required, these results support the notion that coil-based CIs can produce a larger number of independent spectral channels and may therefore improve functional performance. Further, because coil-based devices are structurally similar to existing CIs, fewer impediments to clinical translational are likely to arise.

Variants in CDH23 cause a broad spectrum of hearing loss: from non-syndromic to syndromic hearing loss as well as from congenital to age-related hearing loss

Variants in the CDH23 gene are known to be responsible for both syndromic hearing loss (Usher syndrome type ID: USH1D) and non-syndromic hearing loss (DFNB12). Our series of studies demonstrated that CDH23 variants cause a broad range of phenotypes of non-syndromic hearing loss (DFNB12); from congenital profound hearing loss to late-onset high-frequency-involved progressive hearing loss. In this study, based on the genetic and clinical data from more than 10,000 patients, the mutational spectrum, clinical characteristics and genotype/phenotype correlations were evaluated. The present results reconfirmed that the variants in CDH23 are an important cause of non-syndromic sensorineural hearing loss. In addition, we showed that the mutational spectrum in the Japanese population, which is probably representative of the East Asian population in general, as well as frequent CDH23 variants that might be due to some founder effects. The present study demonstrated CDH23 variants cause a broad range of phenotypes, from non-syndromic to syndromic hearing loss as well as from congenital to age-related hearing loss. Genotype (variant combinations) and phenotype (association with retinal pigmentosa, onset age) are shown to be well correlated and are thought to be related to the residual function defined by the CDH23 variants.

Cochlear Implantation in Advanced Otosclerosis: Pitfalls and Successes

Purpose of Review This review will highlight recent outcome-based evidence guiding decision making for cochlear implantation in advanced otosclerosis, related complications, and technical surgical considerations in otosclerosis and the obstructed cochlea. Recent Findings Cochlear implantation in advanced otosclerosis results in consistent, excellent auditory outcomes with improvement in both objective speech recognition scores and subjective quality of life measures. Facial nerve stimulation may occur at higher rates in otosclerosis cochlear implant recipients. Cochlear implantation in the setting of luminal obstruction in osteosclerotic patients may be managed with altered surgical technique to achieve successful auditory improvements. Pre-operative imaging with high resolution CT or MRI may help anticipate intraoperative challenges and post-operative complications in cochlear implantation. Summary Cochlear implantation is an established, successful treatment for profound hearing loss in advanced otosclerosis. Surgeon knowledge of outcomes, complications, and potential surgical challenges is important to appropriately counsel patients regarding auditory rehabilitation options in advanced otosclerosis.

Englische Zusammenfassungen der Kapitel 1–9

ZusammenfassungAs a whole the effect of an explorative tympanoscopy with sealing the round/oval window(s) in cases of a profound idiopathic unilateral sudden hearing loss (ISSNHL) has been analyzed (data: own study cases and review of literature) and the results have been compared to that of intratympanal steroid injections published elsewhere. In detail the topics of the chapters focused on: Comparison of epidemiologic data, anamnestic and clinical findings including hearing results of our study group with those published Time course of hearing improvement after explorative tympanoscopyand sealing of the round/oval window Compilation of parameters influencing the extent of the initial hearing loss and the hearing gain after surgical therapy Perilymphatic fistulas as an etilogical factor causing a sudden profound hearing loss Comparison of those cases which have been treated by obliteration of the round/oval window with and without corticoid-soaked connective tissue Comparison of patients (data sampled by literature and own cases) treated with intratympanal corticoid injections on the one side or explorative tympanscopy with sealing of the round/oval window on the other side.

Bilateral Sensorineural Hearing Loss in the Setting of Acute Methamphetamine Overdose

Substance abuse is a rare but known cause of sensorineural hearing loss (SNHL). We report a case of acute SNHL in a 28-year-old man following an overdose of methamphetamine and incidental ingestion of fentanyl. On initial encounter, he had moderate-to-severe hearing loss in the right ear and severe-to-profound hearing loss in the left ear in addition to acute kidney injury, liver failure, and lactic acidosis. The patient was treated with a two-week course of high-dose steroids and expressed a subjective improvement in hearing. This case highlights the importance of auditory testing following a drug overdose and is one of the only documented cases of hearing loss following methamphetamine use in recent years. There is a paucity of literature regarding the mechanism causing acute SNHL secondary to methamphetamines. Proposed etiologies include neurotransmitter depletion or reduced cochlear blood flow as possible causes of ototoxicity.

Current criteria for selecting cochlear implant in deaf patients: a review

Cochlear implantation is indicated in patients with severe to profound hearing loss that cannot be adequately treated by other auditory rehabilitation measures. The definitive indication of cochlear implantation is made on the basis of an extensive interdisciplinary clinical, audiological, radiological, and psychological diagnostic work-up. There are numerous changes are happening in cochlear implant candidacy. These have been associated with concomitant changes in surgical techniques, which enhanced the utility and safety of cochlear implantation. Currently, cochlear implants are approved for individuals with severe to profound unilateral hearing loss rather than previously needed for bilateral profound hearing loss. Studies have begun using the short electrode arrays for shallow insertion in patients with low-frequency residual hearing loss. The advancement in designs of the cochlear implant along with improvements in surgical techniques reduce the complications and result in the safety and efficacy of the cochlear implant which further encourages the use of these devices. This review article aims to discuss the new concepts in the candidacy of the cochlear implant, cochlear implant in younger children and hearing preservation, a cochlear implant for unilateral deafness, bilateral cochlear implant, and cochlear implant with neural plasticity and selection of patients for the cochlear implant.

A gyógyszeres kezelésre nem javuló hirtelen halláscsökkenés lépcsőzetes sebészi terápiája

Összefoglaló. A hirtelen halláscsökkenés patofiziológiája még nagyrészt tisztázatlan, így oki terápia nem lehetséges. Az elsődleges kezelést a helyileg vagy szisztémásan adott kortikoszteroid jelenti, egységes protokoll azonban nem áll rendelkezésre. Nagy vagy súlyos fokú hirtelen halláscsökkenés esetén kóroki tényezőként felmerül a perilymphafistula lehetősége még azoknál a betegeknél is, akiknél nem szerepel trauma az anamnézisben. A kórkép műtéti kezelése a dobüreg feltárását követően a belső fül ablakainak obliterálása. Amennyiben ez a megoldás nem eredményez megfelelő hallásjavulást, hagyományos vagy implantálható hallókészülékek alkalmazása javasolt. A közleményben részletezett esetünkben teljes siketséggel járó, jobb oldali hirtelen halláscsökkenés alakult ki, melynek hátterében egyértelmű okot azonosítani nem sikerült. Az eredménytelen kombinált, intratympanalis és szisztémás szteroidkezelést követően exploratív tympanotomiát végeztünk, melynek során a belső fül ablakait obliteráltuk. Hallásjavulást ezt követően sem sikerült kimutatni, így cochlearis implantáció elvégzése mellett döntöttünk. Az implantációt a kerek ablakon keresztül végeztük, mely alapján kijelenthetjük, hogy az előzetes kerekablak-obliteráció nem zárja ki a későbbi cochlearis implantációt. Orv Hetil. 2021; 162(51): 2055–2060. Summary. The pathophysiology of sudden sensorineural hearing loss is mainly unknown, therefore no causative treatment exists. Systemic and local administration of corticosteroids serves as first line therapy although protocols vary. In cases of severe or profound hearing loss with no improvement for medical therapy, perilymphatic fistulae can be assumed even without any history of trauma. Therefore, inner ear window obliteration as a primary surgical option in the early stage can be considered. For patients without complete recovery, conventional hearing aids or implantable hearing devices can be offered. In our case report, we present a patient with right sided idiopathic sudden deafness. After failure of conservative combined intratympanic and systemic steroid therapy, explorative tympanotomy and obliteration of the inner ear windows were performed. As no hearing improvement was witnessed, successful cochlear implantation via round window insertion was performed. Our case justifies that obliterating the round window membrane does not rule out further successful cochlear implantation. Orv Hetil. 2021; 162(51): 2055–2060.

Hearing Rehabilitation with Cochlear Implants after CyberKnife Radiosurgery of Vestibular Schwannoma: A Report Based on Four Clinical Cases

Severe sensorineural hearing loss can be a symptom of the benign tumor vestibular schwannoma (VS). The treatment of VS with non-invasive stereotactic radiosurgery (SRS) offers a high local tumor control rate and an innovative possibility of sequential hearing rehabilitation with cochlear implantation. This study evaluated the feasibility, complications, and auditory outcomes of such a therapeutic approach. Three males and one female (mean age 65.3 ± 9.4 years) scheduled for cochlear implantation and diagnosed with sporadic VS classified as T1 or T2 (according to Samii) were enrolled in this study. All patients had progressive hearing loss qualifying them for cochlear implantation. First, the tumor was treated using CyberKnife SRS. Next, sequential auditory rehabilitation with a cochlear implant (CI) was performed. Clinical outcomes and surgical feasibility were analyzed, and audiological results were evaluated using pure tone audiometry and speech recognition tests. All patients exhibited open-set speech understanding. The mean word recognition score (at 65 dB SPL, Freiburg Monosyllabic Test, FMT) improved after cochlear implantation in all four patients from 5.0 ± 10% (with hearing aid) preoperatively to 60.0 ± 22.7% six months postoperatively. Our results suggest that in patients with profound hearing loss caused by sporadic vestibular schwannoma, the tumor removal with SRS followed by cochlear implantation is an effective method of auditory rehabilitation.

Speech Recognition In Hearing Aids: Used For Assessing CI Candidacy In Tonal Language Population

Objective: CI (cochlear implantation) candidacy is somewhat controversial in severe hearing loss among tonal mandarin-speaking patients. To assess the relationship between pure tone audiometry (PTA) and speech recognition score (SRS), with and without hearing aid amplification, among patients who did not meet the NIH criteria of CI candidacy in tonal language mandarian-speaking countries, especially those with severe hearing loss (70 dB HL < 4FPTA(0.5, 1, 2, 4 KHz) ≤ 90 dB HL) Materials and Methods: A total of 414 patients with sensorineural hearing loss with 774 ears were reviewed retrospectively in a tertiary referral center. The Mandarin Monosyllable Recognition Test (MMRT) was used to evaluate the SRS of these ears. Results: 31% (10/32) of the 32 ears with severe hearing loss, 70-90 dB HL, still showed poor speech recognition (SRS<30%) after hearing aid amplification, while 71% (46/65) of the 65 ears with profound hearing loss, > 90 dB HL, showed poor speech recognition with hearing aid amplification. Conclusions: The speech audiometry with Mandarin Monosyllable Recognition Test (MMRT) helped identify those patients whose 4FPTA< 90 dB HL fell outside the CI candidacy criteria of NIH in tonal language mandarin-speaking countries but showed significantly poor (SRS< 30%) speech recognition performance.