This article reports the development of a neuro-rehabilitation approach, “constraint-induced sound therapy (CIST)” for sudden sensorineural hearing loss. The aim of CIST is to prevent maladaptive cortical reorganization by using an enriched acoustic environment. CIST represents a safe, easy, inexpensive, and effective approach to treat sudden sensorineural hearing loss.
Pludseligt sensorineuralt høretab (SSHL) er kendetegnet ved akut, idiopatisk høretab. Den anslåede incidensrate er 5-30 tilfælde per 100.000 mennesker om året. Årsagerne til SSHL og mekanismerne bag SSHL øjeblikket forbliver ukendte. Baseret på flere hypoteser såsom en kredsløbsforstyrrelse til cochlea, virusinfektion, og autoimmune sygdomme, har Farmakoterapeutisk fremgangsmåder blevet anvendt til behandling af patienter SSHL; Men effektiviteten af standardbehandlingen, corticosteroid terapi, er stadig under debat. Udsættelse for intense lyde har vist sig at forårsage permanent skade på den auditive system; dog udsat for et moderat niveau beriget akustiske miljø efter støj traumer kan reducere hørenedsættelser. Adskillige Neuroimaging undersøgelser for nylig foreslået, at udbruddet af SSHL induceret utilpasset kortikale reorganisering i den menneskelige auditive cortex, og at graden af kortikale reorganisering i den akutte SSHL fasen negativt corropstemt med inddrivelse sats fra høretab. Denne artikel rapporterer udviklingen af en hidtil ukendt neuro-rehabilitering tilgang til SSHL, "constraint-induceret lyd terapi (cist)". Formålet med cist protokollen er at forhindre eller reducere utilpasset kortikale reorganisering ved hjælp af en beriget akustisk miljø. Kanalen af det intakte øre SSHL patienter er sat for at motivere dem til aktivt at bruge de ramte øre og derved forhindre fremskridt utilpasset kortikale reorganisering. Det berørte øre også udsat for musik via hovedtelefoner i 6 timer per dag under indlæggelse. Den cist protokol synes at være en sikker, nem, billig og effektiv behandling for SSHL.
Pludseligt sensorineuralt høretab (SSHL) eller pludselig døvhed, er en idiopatisk tilstand, der er karakteriseret ved en hurtig tab af hørelse 1. Adskillige epidemiologiske undersøgelser 2,3 rapporteret SSHL forekomst af 5-30 tilfælde per 100.000 mennesker om året i de industrialiserede lande. Selvom årsagerne til SSHL og de mekanismer der ligger til grund SSHL er blevet undersøgt udførligt, vores viden om SSHL fortsat begrænset. Blandt de mange mulige årsager til idiopatisk SSHL, fælles hypoteser omfatter en kredsløbsforstyrrelse 4, virusinfektion 5-7, og autoimmune sygdomme 8,9. Selvom kortikosteroidbehandling 10 blev foreslået på grundlag af disse hypoteser, og er den mest almindeligt anvendte behandling, er effektiviteten af denne standardbehandling stadig debatteret 3,11-14. Derfor innovative SSHL behandlingsstrategier, motiveret af forskellige perspektiver, er stærkt ønsket.
SSHLpåvirker neurale aktivitet ikke kun i cochlea, men også i den auditive cortex. Adskillige Neuroimaging undersøgelser 15-17 foreslog, at SSHL induceret kortikal plasticitet i den menneskelige auditive cortex inden for et par dage efter debut. Desuden er graden af kortikale reorganisering repræsenteret ved tabet af kontralaterale halvkugleformet dominancy af auditive evoked felter syntes at negativt korrelere med genvindingskvoterne af høretab 18. Det kortikale plasticitet induceret af indtræden af SSHL kan betragtes som utilpasset for hørelse kapacitet af det påvirkede øre. Derfor kan forebyggelse af denne utilpasset kortikale reorganisering forbundet med SSHL repræsenterer en ny behandlingsstrategi.
Denne artikel foreslår en neuro-rehabilitering tilgang, der forhindrer "lært manglende brug 'kortikale ændringer for at forebygge eller reducere utilpasset kortikale reorganisering. For eksempel i tilfælde af motorisk dysfunktion, den lærde manglende brug afen limbis et fænomen, hvor bevægelsen er i første omgang undertrykkes på grund af bivirkninger og svigt af enhver aktivitet forsøgt med de ramte led, som i sidste ende resulterer i undertrykkelse af adfærd og tilsvarende neurale aktivitet 19,20. Lærte manglende brug synes ikke at være begrænset til motorisk dysfunktion, men kan også vedrøre sensoriske handicap 21. SSHL patienter primært bruger og være opmærksomme på den intakte øre til at lytte. Denne lytte adfærd synes at øge neurale aktivitet svarende til ubeskadiget øre og, på samme tid, reducere neurale forbindelser mellem de berørte cochlea og auditive cortex 22. For at forhindre dette utilpasset kortikale ændring induceret af 'manglende brug «, synes det at være en fordel for SSHL patienter til at udføre" constraint-induceret lyd terapi (cist) '23, der motiverer deltagerne til at lytte til musik intensivt via de ramte øre og betaler auditive opmærksom på det angrebne øre(Figur 1). Sammenlignet med konventionel farmakoterapi, at cist angiveligt er en sikker, nem, billig og effektiv tilgang behandling for SSHL.
This article describes a behavioral treatment approach for SSHL. The CIST protocol merely requires the use of easily available devices. A comparison of the treatment effects of CIST + SCT with those of SCT alone revealed significantly better hearing improvements with the CIST + SCT treatment. No apparent side effects were associated with the CIST protocol. The cost of CIST is markedly lower than other newly suggested treatments (including a stellate ganglion block and hyperbaric oxygen therapy). The CIST protocol represents an effective, inexpensive, easy, and safe treatment for SSHL; however, several important points must be considered. One point is the prevention of acoustic trauma. Although the maximal volume settings of recent commercial portable music players are limited to remain below the harmful levels, the sound level needs to be observed when a large adjustment is made to the equalizer settings or when a headphone amplifier is used. The second point is ‘cross hearing’. The purpose of the CIST procedure is to enable SSHL patients to actively use their affected ear for listening. When patients develop severe hearing loss, they may still hear sounds with the intact ear despite plugging. The third point is ‘accidents’. In the case of traditional pharmacotherapy, the intact ear is not plugged, and thus SSHL patients can pick up environmental sounds via this intact ear. On the other hand, plugging and music listening inherent to the CIST protocol seal patients from environmental sounds, and thus the accident hazard is likely increased. Therefore, the CIST protocol should be conducted in a safe environment.
Unlike pharmacotherapy, the CIST protocol has no limitations concerning medications, allergies, or other diseases such as diabetes, hypertension, and hyperlipidemia. However, the limitation of this protocol is that it is intended for patients who are able to listen to sounds with their affected ear. As such, the CIST protocol is not suited for SSHL patients with severe hearing loss. This protocol is applied to acute stage SSHL (days since SSHL onset ≤ 5) because previous studies reported that a shorter time delay between the onset of SSHL and the start of treatment led to better hearing recovery2. It remains elusive whether there is a time restriction for starting the CIST protocol. Moreover, the optimum duration of the CIST protocol and the total music listening time require further investigation.
This protocol utilizes the corticosteroid therapy in addition to CIST. At present, corticosteroids are the most commonly used treatment for SSHL, and therefore it is ethically not feasible to stop this treatment. However, recent triple-blinded SSHL treatment studies14 revealed that the recovery of non-treated patients was similar to that of patients who had received corticosteroids. Even though one cannot exclude the possibility that the combination of CIST + SCT led to the results obtained, it appears reasonable to assume that CIST alone will be beneficial, especially for patients with diseases that are worsened by corticosteroids such as infections, diabetes, and glaucoma.
In this protocol, patients are hospitalized in order to avoid accidents. However, SSHL patients often cannot be hospitalized because of work, family, and financial reasons. The utilization of a hearing aid may allow these outpatients to perform the CIST protocol. SSHL patients who wear a hearing aid in their affected ear are ‘functionally’ exposed to an enriched acoustic environment, are not in danger to be exposed to harmful sound levels, and are able to detect warning sound signals. However, the daily monitoring of hearing threshold levels and appropriate adjustments to the hearing aid settings would be necessary since hearing capability of SSHL patients can improve rapidly. Generally, the CIST protocol will not disturb other treatment approaches and may actually manifest a synergic effect when used in combination with other SSHL treatment strategies.
In the present study, a limited number of SSHL patients underwent the CIST protocol, and the participants were not randomized to the different treatment conditions. Thus, a randomized controlled study including a larger number of patients should be executed in the future. Moreover, the effectiveness of the CIST protocol should be investigated in patients with different types of hearing loss. Further, in the present study, all participants who performed the CIST protocol also received the corticosteroid therapy. Therefore, it remains unresolved whether the CIST protocol alone can improve the hearing ability of SSHL patients. It would be valuable to perform a randomized controlled study in which SSHL patients, for whom corticosteroids may cause severe side effects (such asinfectious diseases or diabetes mellitus), would either merely receive the CIST protocol or merely a standard corticosteroid therapy. Notably, in our previous report23, the effects of the CIST protocol within the human auditory cortex were examined by means of magnetoencephalography35. The results showed that the CIST protocol could have prevented maladaptive cortical reorganization in the human primary and non-primary auditory cortices. Of course, it is difficult to conduct neuroimaging studies in practices and hospitals; however, speech test, hearing in noise test36, and tinnitus related examinations37 may contribute to reveal the functional plasticity in the central auditory system induced by the CIST protocol. Eventually, even though the CIST protocol is in a very early stage in development, and although further investigations are needed, the CIST protocol as an effective, inexpensive, and safe treatment option can complement the corticosteroid therapy, which may induce severe and potentially lethal side effects.
The authors have nothing to disclose.
We thank Yoshimasa Sekiya for demonstrating the protocol technique on film. This work was supported by the ”Japan Society for the Promotion of Science for Young Scientists (26861426)” and by the “COI STREAM (Center of Innovation Science and Technology based Radical Innovation and Entrepreneurship Program)”.
Ear mold | RION Co.Ltd, Tokyo, Japan | EM-59 | |
portable music player | Sony Corporation, Tokyo, Japan | NW-S775 | |
headphone | SENNHEISER Electronic GmbH & Co. KG, Hannover, Germany | HD280pro | |
equalizer | Roland Corporation, Hamamatsu, Japan | GE-7 | |
headphone amplifier | FiiO Electronics Technology Co. Ltd, Guangzhou, China | E11 | |
sound editing application | Adobe Systems Inc., CA, USA | Audition 3.0 |