Die Rolle der kochleären Neurotransmitter in Bezug auf Tinnitus

Application and prospect of quasi-targeted metabolomics in age-related hearing loss

Age-related hearing loss (ARHL) is a common sensory deficit in the elderly, which seriously affects physical and mental health. Therefore, understanding its underlying molecular mechanisms and taking interventions to treat ARHL are urgently needed. In our study, cochlea of 4-week-old C57BL/6 mice as the Youth group (n = 6) and 48-week-old cochlea as the Old group (n = 6) were subjected to quasi-targeted metabolomics analysis by Ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). In total, 208 differential metabolites were identified in 12 cochlea samples, which highlighted the following discriminant compounds: tryptophan, piperidine, methionine, L-arginine, histamine, serotonin, acetylcholine, and 4-aminobutyric acid. Differentially expressed metabolites were identified which were involved in KEGG pathways related to the digestion and absorption of oxidative stress associated amino acids, Synaptic vesicle cycle of serotonin, Pantothenate and CoA Biosynthesis. These findings are a first step toward elucidating the pathophysiological pathways involved in the etiology of ARHL and provide the possibility to further explore the mechanisms of ARHL using metabolomic analysis.

Does cannabis alleviate tinnitus? A review of the current literature

OBJECTIVES

Endocannabinoid pathways have been proposed to affect the underlying pathophysiology of tinnitus. The aim of this study is to evaluate the scope and findings of existing literature on the relationship between cannabis and cannabinoid pathways and tinnitus.

METHODS

We conducted a review of animal, clinical and survey studies investigating the relationship between the use of cannabis-derived agents and tinnitus. Using pertinent keywords and MeSH terms on PubMed, relevant studies were identified, yielding four animal studies, two large cross-sectional survey studies, one clinical cross-over study, and one case report.

RESULTS

Animal studies revealed that cannabinoid receptor expression in the cochlear nucleus varied with tinnitus symptomatology and the use of cannabinoid agents either increased or had no effect on tinnitus-related behavior. Survey studies yielded conflicting results between cannabis use and tinnitus in the general population. Clinical data is largely lacking, although a small cohort study showed a dose-dependent relationship between tetrahydrocannabinol consumption and frequency of tinnitus episodes in patients receiving treatment for cancer.

CONCLUSION

While animal studies have revealed that cannabinoid receptors likely have a role in modulating auditory signaling, there is no compelling data either from animal or human studies for the use of cannabinoids to alleviate tinnitus. Further research is necessary to elucidate their precise role to guide development of therapeutic interventions.

LEVEL OF EVIDENCE

NA.

Development of Tinnitus at a Low Dose of Sertraline: Clinical Course and Proposed Mechanisms

Introduction. Serotonin is involved in filtering of auditory stimuli. Cochlear input is processed through complex interactions between serotonergic, glutamatergic, and GABAergic neurotransmitter systems. Options for treatment of tinnitus include selective serotonin reuptake inhibitors (SSRIs); however in rare instances this symptom may occur as a side effect of this class of medications. Case Presentation. A 50-year-old woman developed bilateral tinnitus after several weeks of being treated with sertraline 50 mg. She had been on a long-standing daily dose of aspirin 325 mg which had been discontinued shortly before starting sertraline. Medical work-up was negative for her symptom. Shortly after discontinuation of the medication, her tinnitus subsided completely. Discussion. Tinnitus is a rare side effect of sertraline and may be related to particular distribution of serotonin receptor subtypes within the auditory system, and serotonergic agents may reinforce or desensitize the activity of different receptors. Also, there may be a priming effect of salicylate agents on the auditory system, predisposing particular patients to be more sensitive to how auditory stimuli are processed.

Ginkgo biloba for tinnitus

BACKGROUND

This is an update of a Cochrane review first published in The Cochrane Library in Issue 2, 2004 and previously updated in 2007 and 2009.Tinnitus can be described as the perception of sound in the absence of external acoustic stimulation. At present no specific therapy for tinnitus is acknowledged to be satisfactory in all patients. There are a number of reports in the literature suggesting that Ginkgo biloba may be effective in the management of tinnitus. However, there also appears to be a strong placebo effect in tinnitus management.

OBJECTIVES

To assess the effect of Ginkgo biloba in patients who are troubled by tinnitus.

SEARCH METHODS

We searched the Cochrane Ear, Nose and Throat Disorders Group Trials Register; the Cochrane Central Register of Controlled Trials (CENTRAL); PubMed; EMBASE; AMED; Web of Science; BIOSIS Previews; Cambridge Scientific Abstracts; ICTRP and additional sources for published and unpublished trials. The date of the most recent search was 12 March 2012.

SELECTION CRITERIA

Adults (18 years and over) complaining of tinnitus or adults with a primary complaint of cerebral insufficiency, where tinnitus forms part of the syndrome.

DATA COLLECTION AND ANALYSIS

Both original authors independently extracted data and assessed trials for quality. For the 2012 update two authors determined trial eligibility, extracted data, analysed data and updated the contents of the review.

MAIN RESULTS

Four trials with a total of 1543 participants were included in the review; we assessed all the included studies as having a low risk of bias. Three trials (1143 participants) included patients with a primary complaint of tinnitus and one (400 participants) included patients with mild to moderate dementia, some of whom had tinnitus.There was no evidence that Gingko biloba was effective in patients with a primary complaint of tinnitus. In the study of patients with dementia, mean baseline levels of tinnitus were low (1.7 to 2.5 on a 10-point subjective symptom rating scale). A small but statistically significant reduction of 1.5 and 0.7 points was seen in patients taking Gingko biloba with vascular dementia and Alzheimer's disease respectively. The practical clinical significance of this is unclear. The incidence of side effects was low.

AUTHORS' CONCLUSIONS

The limited evidence does not demonstrate that Ginkgo biloba is effective for tinnitus when this is the primary complaint.

Sound therapy (masking) in the management of tinnitus in adults

BACKGROUND

This is an update of a Cochrane Review first published in The Cochrane Library in Issue 12, 2010.Tinnitus is described as the perception of sound or noise in the absence of real acoustic stimulation. Numerous management strategies have been tried for this potentially debilitating, heterogeneous symptom. External noise has been used as a management tool for tinnitus, in different capacities and with different philosophical intent, for over a century.

OBJECTIVES

To assess the effectiveness of sound-creating devices (including hearing aids) in the management of tinnitus in adults. Primary outcome measures were changes in the loudness or severity of tinnitus and/or impact on quality of life. Secondary outcome measures were change in pure-tone auditory thresholds and adverse effects of treatment. 

SEARCH METHODS

We searched the Cochrane ENT Group Trials Register; CENTRAL; PubMed; EMBASE; CINAHL; Web of Science; BIOSIS Previews; Cambridge Scientific Abstracts; ICTRP and additional sources for published and unpublished trials. The date of the most recent search was 8 February 2012.

SELECTION CRITERIA

Prospective randomised controlled trials recruiting adults with persistent, distressing, subjective tinnitus of any aetiology in which the management strategy included maskers, noise-generating device and/or hearing aids, used either as the sole management tool or in combination with other strategies, including counselling.

DATA COLLECTION AND ANALYSIS

Two authors independently examined the 387 search results to identify studies for inclusion in the review, of which 33 were potentially relevant. The update searches in 2012 retrieved no further potentially relevant studies. Both authors extracted data independently.

MAIN RESULTS

Six trials (553 participants) are included in this review. Studies were varied in design, with significant heterogeneity in the evaluation of subjective tinnitus perception, with different scores, scales, tests and questionnaires as well as variance in the outcome measures used to assess the improvement in tinnitus sensation/quality of life. This precluded meta-analysis of the data. There was no long-term follow-up. We assessed the risk of bias as medium in three and high in three studies. Following analysis of the data, no significant change was seen in the loudness of tinnitus or the overall severity of tinnitus following the use of sound therapy compared to other interventions such as patient education, 'relaxation techniques', 'tinnitus coping strategies', counselling, 'tinnitus retraining' and exposure to environmental sounds. No side effects or significant morbidity were reported from the use of sound-creating devices.

AUTHORS' CONCLUSIONS

The limited data from the included studies failed to show strong evidence of the efficacy of sound therapy in tinnitus management. The absence of conclusive evidence should not be interpreted as evidence of lack of effectiveness. The lack of quality research in this area, in addition to the common use of combined approaches (hearing therapy plus counselling) in the management of tinnitus are, in part, responsible for the lack of conclusive evidence. Other combined forms of management, such as tinnitus retraining therapy, have been subject to a Cochrane Review. Optimal management may involve multiple strategies.

Repetitive transcranial magnetic stimulation for tinnitus

BACKGROUND

Tinnitus is the perception of sound, in the ear or in the head, in the absence of any external acoustic stimulation. Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive means of inducing electrical currents in the brain, and has received increasing attention in recent years for the treatment of many neuropsychiatric disorders, including tinnitus.

OBJECTIVES

To assess the effectiveness and safety of rTMS versus placebo in patients with tinnitus.

SEARCH STRATEGY

We searched the Cochrane Ear, Nose and Throat Disorders Group Trials Register; the Cochrane Central Register of Controlled Trials (CENTRAL); PubMed; EMBASE; CINAHL; Web of Science; BIOSIS Previews; Cambridge Scientific Abstracts; ICTRP and additional sources for published and unpublished trials. The date of the most recent search was 24 May 2011.

SELECTION CRITERIA

Randomised controlled trials of rTMS versus sham rTMS.

DATA COLLECTION AND ANALYSIS

Two review authors reviewed the titles, abstracts and keywords of all records retrieved. Three review authors independently collected and extracted data, and assessed the risk of bias of the trials.

MAIN RESULTS

Five trials comprising of 233 participants met our inclusion criteria. Each study described the use of a different rTMS device that delivered different waveforms at different frequencies. All five trials were relatively small studies but generally they demonstrated a low risk of bias.When considering the impact of tinnitus on patients' quality of life, the results of only one study demonstrated a statistically significant improvement in Tinnitus Handicap Inventory (THI) scores at four months follow-up (defined as a 'partial improvement' by the study authors (THI reduction of 21% to 80%)) when low-frequency rTMS was compared with a sham control treatment. However, no statistically significant improvement was demonstrated by another two studies that considered rTMS at the same frequency. Furthermore, this single positive finding should be taken in the context of the many different variables which were recorded at many different points in time by the study authors.In accordance with our pre-specified subgroup analysis we extracted the data from one study to consider the differential effectiveness between 'lower' low-frequency rTMS (1 Hz) and 'higher' low-frequency rTMS (10 Hz, 25 Hz). In doing this we were able to demonstrate a statistically significant difference between rTMS employing a frequency of 1 Hz and the sham group when considering tinnitus severity and disability after four months follow-up ('partial' improvement). However, no statistically significant difference was demonstrated between 10 Hz and 25 Hz rTMS, and the sham control group, when considering the severity and disability of tinnitus at four months follow-up.When considering tinnitus loudness in patients undergoing rTMS we were able to demonstrate a statistically significant reduction in tinnitus loudness when the results of two studies were pooled (risk ratio 4.17, 95% confidence interval 1.30 to 13.40). However, this finding was based on two small trials and consequently the confidence interval was particularly wide.No serious adverse effects were reported in any of the trials.

AUTHORS' CONCLUSIONS

There is very limited support for the use of low-frequency rTMS for the treatment of patients with tinnitus. When considering the impact of tinnitus on patients' quality of life, support is from a single study with a low risk of bias based on a single outcome measure at a single point in time. When considering the impact on tinnitus loudness, this is based on the analysis of pooled data with a large confidence interval.Studies suggest that rTMS is a safe treatment for tinnitus in the short-term, however there were insufficient data to provide any support for the safety of this treatment in the long-term.More prospective, randomised, placebo-controlled, double-blind studies with large sample sizes are needed to confirm the effectiveness of rTMS for tinnitus patients. Uniform, validated, tinnitus-specific questionnaires and measurement scales should be used in future studies.

[Molecular biological aspects of neuroplasticity: approaches for treating tinnitus and hearing disorders]

Peripheral and central structures are involved in the onset of tinnitus. Neuronal plasticity is of special importance for the occurrence of central tinnitus and its persistent form. Neuronal plasticity is the ability of the brain to adapt its own structure (synapses, nerve cells, or even whole areas of the brain) and its organization to modified biological requirements. Neuroplasticity is an ongoing dynamic process. Generally speaking, there are two types of plasticity: synaptic and cortical. Cortical plasticity involves activity-dependent changes in size, connectivity, or in the activation pattern of cortical networks. Synaptic plasticity refers to the activity-dependent change in the strength of synaptic transmission and can affect both the morphology and physiology of the synapse. The stimulation of afferent fibers leads to long-lasting changes in synaptic transmission. This phenomenon is called long-term potentiation (LTP) or long-term depression (LTD). From the perspective of molecular biology, synaptic plasticity is of particular importance for the development of tinnitus and its persistence. Ultimately, the damage to the hair cells, auditory nerve, and excitotoxicity results in an imbalance between LTP and LTD and thus in changes of synaptic plasticity. After excessive acoustic stimulation, LTP can be induced by the increase of afferent inputs, whereas decreased afferent inputs generate LTD. The imbalance between LTP and LTD leads to changes in gene expression and involves changes in neurotransmission, in the expression of the receptors, ion channels, regulatory enzymes, and in direct changes on the synapses. This causes an increase of activity on the cellular level. As a result, the imbalance can lead to hyperactivity in the dorsal cochlear nucleus, inferior colliculus, and in the auditory cortex and, later on, to changes in cortical plasticity leading to tinnitus.

Sound therapy (masking) in the management of tinnitus in adults

BACKGROUND

Tinnitus is described as the perception of sound or noise in the absence of real acoustic stimulation. Numerous management strategies have been tried for this potentially debilitating, heterogeneous symptom. External noise has been used as a management tool for tinnitus, in different capacities and with different philosophical intent, for over a century.

OBJECTIVES

To assess the effectiveness of sound-creating devices (including hearing aids) in the management of tinnitus in adults. Primary outcome measures were changes in the loudness or severity of tinnitus and/or impact on quality of life. Secondary outcome measures were change in pure-tone auditory thresholds and adverse effects of treatment. 

SEARCH STRATEGY

We searched the Cochrane ENT Group Trials Register; CENTRAL (2009, Issue 3); PubMed; EMBASE; CINAHL; Web of Science; BIOSIS Previews; Cambridge Scientific Abstracts; mRCT and additional sources for published and unpublished trials. The date of the most recent search was 11 September 2009.

SELECTION CRITERIA

Prospective randomised controlled trials recruiting adults with persistent, distressing, subjective tinnitus of any aetiology in which the management strategy included maskers, noise-generating device and/or hearing aids, used either as the sole management tool or in combination with other strategies, including counselling.

DATA COLLECTION AND ANALYSIS

Two authors independently examined the 362 search results to identify studies for inclusion in the review, of which 33 were potentially relevant. Both authors extracted data independently.

MAIN RESULTS

Six trials (553 participants) are included in this review. Studies were varied in design, with significant heterogeneity in the evaluation of subjective tinnitus perception, with different scores, scales, tests and questionnaires as well as variance in the outcome measures used to assess the improvement in tinnitus sensation/quality of life. This precluded meta-analysis of the data. There was no long-term follow up. We assessed the risk of bias as medium in three and high in three studies. No side effects or significant morbidity were reported from the use of sound-creating devices.

AUTHORS' CONCLUSIONS

The limited data from the included studies failed to show strong evidence of the efficacy of sound therapy in tinnitus management. The absence of conclusive evidence should not be interpreted as evidence of lack of effectiveness. The lack of quality research in this area, in addition to the common use of combined approaches (hearing therapy plus counselling) in the management of tinnitus are, in part, responsible for the lack of conclusive evidence. Other combined forms of management, such as Tinnitus Retraining Therapy, have been subject to a Cochrane Review. Optimal management may involve multiple strategies.

Cognitive behavioural therapy for tinnitus

BACKGROUND

This is an update of a Cochrane Review originally published in Issue 1, 2007 of The Cochrane Library.Tinnitus is an auditory perception that can be described as the experience of sound, in the ear or in the head, in the absence of external acoustic stimulation. Cognitive behavioural therapy (CBT) uses relaxation, cognitive restructuring of the thoughts and exposure to exacerbating situations in order to promote habituation and may benefit tinnitus patients, as may the treatment of associated psychological conditions.

OBJECTIVES

To assess whether CBT is effective in the management of patients suffering from tinnitus.

SEARCH STRATEGY

We searched the Cochrane Ear, Nose and Throat Disorders Group Trials Register; the Cochrane Central Register of Controlled Trials (CENTRAL); PubMed; EMBASE; CINAHL; Web of Science; BIOSIS Previews; Cambridge Scientific Abstracts; PsycINFO; ISRCTN and additional sources for published and unpublished trials. The date of the most recent search was 6 May 2010.

SELECTION CRITERIA

Randomised controlled trials in which patients with unilateral or bilateral tinnitus as their main symptom received cognitive behavioural treatment.

DATA COLLECTION AND ANALYSIS

One review author (PMD) assessed every report identified by the search strategy. Three authors (PMD, AW and MT) assessed the methodological quality and applied inclusion/exclusion criteria. Two authors (PMD and RP) extracted data and conducted the meta-analysis. The four authors contributed to the final text of the review.

MAIN RESULTS

Eight trials comprising 468 participants were included.For the primary outcome of subjective tinnitus loudness we found no evidence of a difference between CBT and no treatment or another intervention (yoga, education and 'minimal contact - education').In the secondary outcomes we found evidence that quality of life scores were improved in participants who had tinnitus when comparing CBT to no treatment or another intervention (education and 'minimal contact education'). We also found evidence that depression scores improved when comparing CBT to no treatment. We found no evidence of benefit in depression scores when comparing CBT to other treatments (yoga, education and 'minimal contact - education').There were no adverse/side effects reported in any trial.

AUTHORS' CONCLUSIONS

In six studies we found no evidence of a significant difference in the subjective loudness of tinnitus.However, we found a significant improvement in depression score (in six studies) and quality of life (decrease of global tinnitus severity) in another five studies, suggesting that CBT has a positive effect on the management of tinnitus.

Tinnitus Retraining Therapy (TRT) for tinnitus

BACKGROUND

Tinnitus is described as the perception of sound or noise in the absence of real acoustic stimulation. Although an outright cure for tinnitus remains elusive, various management strategies have been developed to help to lessen the impact of the symptom. Following the publication of a neurophysiological model of tinnitus, Tinnitus Retraining Therapy (TRT) was developed. Using a combination of directive counselling and sound therapy in a strict framework, this is one of the most commonly used treatment modalities for tinnitus. Many studies refer to the use of TRT where in fact a modified version of this therapy is actually being implemented. It is therefore important to confirm the use of authentic TRT when reviewing any study that reports its use.

OBJECTIVES

To assess the efficacy of TRT in the treatment of tinnitus.

SEARCH STRATEGY

The search included the Cochrane ENT Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, EMBASE and reference lists of identified publications. The date of the most recent search was 26 August 2009.

SELECTION CRITERIA

Randomised controlled trials of TRT versus no treatment, or other forms of treatment, in adult patients with tinnitus.

DATA COLLECTION AND ANALYSIS

Both authors critically appraised the retrieved studies for risk of bias and extracted data independently. Where necessary, we contacted the original study authors for further information.

MAIN RESULTS

Only one trial (123 participants) was included in the review. Several excluded trials did not follow the strict protocol for TRT, evaluating instead a modified form of TRT. The included trial showed TRT to be more effective than a tinnitus masking (TM) approach. In this study outcome data for tinnitus severity were presented using three instruments (Tinnitus Handicap Inventory (THI), Tinnitus Handicap Questionnaire (THQ), Tinnitus Severity Index (TSI)) for patients in three groups (participants' tinnitus being a 'moderate problem', big problem' or 'very big problem').At 18 months, improvements for the three groups in the three scores (TRT versus TM) were respectively: 'moderate problem' - THI: 18.2 versus 4.6, THQ: 489 versus 178, TSI 7.5 versus 1.6; 'big problem' - THI: 29.2 versus 16.7, THQ: 799 versus 256, TSI: 12.1 versus 6.7; and 'very big problem' - THI: 50.4 versus 10.3, THQ; 1118 versus 300, TSI: 19.7 versus 4.8.

AUTHORS' CONCLUSIONS

A single, low-quality randomised controlled trial suggests that TRT is much more effective as a treatment for patients with tinnitus than tinnitus masking.

Ginkgo biloba for tinnitus

BACKGROUND

Tinnitus can be described as the perception of sound in the absence of external acoustic stimulation. At present no specific therapy for tinnitus is acknowledged to be satisfactory in all patients. There are a number of reports in the literature suggesting that Ginkgo biloba may be effective in the management of tinnitus. However, there also appears to be a strong placebo effect in tinnitus management.

OBJECTIVES

To assess the effect of Ginkgo biloba in patients who are troubled by tinnitus.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library Issue 4 2003), MEDLINE (1966 - 2003), EMBASE (1974 - 2003), and reference lists of identified publications. Date of the most recent search was December 2003.

SELECTION CRITERIA

Adults (18 years and over) complaining of tinnitus. Adults with a primary complaint of cerebral insufficiency where tinnitus forms part of the syndrome.

DATA COLLECTION AND ANALYSIS

Both reviewers independently extracted data and assessed trials for quality.

MAIN RESULTS

Twelve trials were identified from the search as being relevant to the review. Ten trials were excluded on methodological grounds. No trials of tinnitus in cerebral insufficiency reached a satisfactory standard for inclusion in the review. There was no evidence that Ginkgo biloba was effective for the primary complaint of tinnitus. The incidence of side effects was small.

REVIEWERS' CONCLUSIONS

The limited evidence did not demonstrate that Ginkgo biloba was effective for tinnitus which is a primary complaint. There was no reliable evidence to address the question of Ginkgo biloba for tinnitus associated with cerebral insufficiency.