Invasive Neuromodulation as a Treatment for Tinnitus: A Systematic Review

[S3-Guideline Chronic Tinnitus - Update]

Chronic tinnitus is a symptom of disturbed auditory perception. More than 90% of tinnitus patients suffer from hearing loss. Many people experience tinnitus and seek for treatment, but suffering and actual burden of tinnitus is individually very different, sometimes it disappears after a certain time even without treatment. This process is called habituation. The actual suffering from tinnitus depends on stress symptoms and other psychosomatic comorbidities like depression, anxiety and sleeping disorders.Up-to-date there is no therapy that can completely switch off tinnitus, mainly because the origin and expression of tinnitus are individual and very different. This educational publication summarizes and evaluates scientific therapeutic approaches for chronic tinnitus, based on the newly elaborated S3-Guideline "Chronic Tinnitus", under the lead management of the German Society of ENT, Head and Neck-Surgery, published in 2021. It focusses on recommendations for counselling, interventions against hearing loss and psychotherapy, mainly cognitive behavioural therapy.

Abnormal Rhomboid Lip and Choroid Plexus Should be Valued in Microvascular Decompression for Vestibulocochlear Diseases

BACKGROUND

Surgical outcomes for functional vestibulocochlear diseases vary, and the influencing factors are not fully understood. The role of a rhomboid lip (RL) and choroid plexus (CP) in microvascular decompression (MVD) of the vestibulocochlear nerve has not been studied. This study aims to evaluate the surgical efficacy of MVD for vestibulocochlear diseases, with and without addressing the RL and CP, to enhance our understanding of their etiology.

METHODS

A total of 15 patients who underwent MVD for the vestibulocochlear nerve between 2013 and 2022 were retrospectively identified and followed up. The patients were classified into 4 categories: vestibular paroxysmia (VP), benign positional paroxysmal vertigo (BPPV), and Meniere disease (MD). The fourth was a "tinnitus" group. The relief of symptoms, recurrence, satisfaction after surgery, available relevant imaging studies, and intraoperative observation data were evaluated.

RESULTS

Following MVD, 6 of the 7 patients in the VP group, the 1 patient in the BPPV group, and 1 of 2 patients in the MD group were completely relieved of vertigo. The seventh VP patient showed significant improvement. The 5 patients in the "tinnitus" group remained unchanged. Retrospectively, 4 patients from the VP, BPPV, and MD groups who underwent RL incision and CP excision were also free of vertigo, although vascular compression was not confirmed in these cases.

CONCLUSIONS

MVD is generally considered a useful treatment for VP and could also be effective in managing recurrent vertigo caused by BPPV and MD. Our results highlight the potential role of an abnormal RL and CP in the development of vertigo symptoms. Patients presenting with "tinnitus" require further investigation and might not be suitable for MVD.

Functional Brain Regions Linked to Tinnitus Pathology and Compensation During Task Performance: A Systematic Review

OBJECTIVE

To systematically search the literature and organize relevant advancements in the connection between tinnitus and the activity of different functional brain regions using functional magnetic resonance imaging (fMRI).

DATA SOURCES

MEDLINE (OVID), EMBASE (OVID), CINAHL (EBSCO), Web of Science, ProQuest Dissertations & Theses Global, Cochrane Database of Systematic Reviews, and PROSPERO from inception to April 2022.

REVIEW METHODS

Studies with adult human subjects who suffer from tinnitus and underwent fMRI to relate specific regions of interest to tinnitus pathology or compensation were included. In addition, fMRI had to be performed with a paradigm of stimuli that would stimulate auditory brain activity. Exclusion criteria included non-English studies, animal studies, and studies that utilized a resting state magnetic resonance imaging or other imaging modalities.

RESULTS

The auditory cortex may work to dampen the effects of central gain. Results from different studies show variable changes in the Heschl's gyrus (HG), with some showing increased activity and others showing inhibition and volume loss. After controlling for hyperacusis and other confounders, tinnitus does not seem to influence the inferior colliculus (IC) activation. However, there is decreased connectivity between the auditory cortex and IC. The cochlear nucleus (CN) generally shows increased activation in tinnitus patients. fMRI evidence indicates significant inhibition of thalamic gating. Activating the thalamus may be of important therapeutic potential.

CONCLUSION

Patients with tinnitus have significantly altered neuronal firing patterns, especially within the auditory network, when compared to individuals without tinnitus. Tinnitus and hyperacusis commonly coexist, making differentiation of the effects of these 2 phenomena frequently difficult.

Neurofeedback for tinnitus treatment: an innovative method with promising potential

This scientific commentary refers to 'Does it matter what is trained? A randomized controlled trial evaluating the specificity of alpha/delta ratio neurofeedback in reducing tinnitus symptoms 'by Jensen et al. (https://doi.org/10.1093/braincomms/fcad185).

Therapeutic effects of Rosa canina, Urtica dioica and Tanacetum vulgare herbal combination in treatment of tinnitus symptoms: A double-blind randomised clinical trial

OBJECTIVE

To evaluate the effect of Neurotec® herbal capsule (100 mg twice a day for 3 months) on the tinnitus symptoms in comparison with the placebo.

DESIGN

A double-blind randomised clinical trial.

SETTING

Otolaryngology clinic of Baqiyatallah Hospital.

PARTICIPANTS

Patients suffering from subjective tinnitus.

MAIN OUTCOME MEASURES

Pure tone audiometry was measured at .5, 1, 2, 4 and 6 kHz frequencies before and after the third month of intervention. In addition, Tinnitus Handicap Inventory (THI) questionnaire as well as visual analogue scale (VAS) for tinnitus loudness, daily annoyance, daily life or sleep disturbance, daily perception and mood alteration were evaluated.

RESULTS

Finally, 103 (69 males and 34 females) patients with a mean age of 51.33 ± 13.91 years were analysed. In contrast with control group, patients in intervention group showed a remarkable decrease in THI score after 3 months of treatment (p < .05). Although both groups had improvements in VAS scores, mood disturbance, daily tinnitus perception and daily life alteration scores were only improved in the intervention group. The mean pure tone air and bone conduction were not significantly different between the control and the intervention group at baseline and 3 months after the intervention at .5, 1, 2 and 4 kHz (p > .05).

CONCLUSION

A 3-month treatment with Neurotec capsules in addition to patient education is of benefit for managing symptoms in patients with chronic tinnitus.

State of the art: non-invasive electrical stimulation for the treatment of chronic tinnitus

Subjective tinnitus is the perception of sound in the absence of external stimulation. Neuromodulation is a novel method with promising properties for application in tinnitus management. This study sought to review the types of non-invasive electrical stimulation in tinnitus to provide the foothold for further research. PubMed, EMBASE, and Cochrane databases were searched for studies on the modulation of tinnitus by non-invasive electrical stimulation. Among the four forms of non-invasive electrical modulation, transcranial direct current stimulation, transcranial random noise stimulation, and transauricular vagus nerve stimulation yielded promising results, whereas the effect of transcranial alternating current stimulation in the treatment of tinnitus has not been confirmed. Non-invasive electrical stimulation can effectively suppress tinnitus perception in some patients. However, the heterogeneity in parameter settings leads to scattered and poorly replicated findings. Further high-quality studies are needed to identify optimal parameters to develop more acceptable protocols for tinnitus modulation.

Evaluation and Management of Tinnitus: Are There Opportunities for Improvement?

OBJECTIVE

To review current information about diagnosis and management of tinnitus aiming to identify opportunities for achieving a cost-effective, efficient, evidence-based approach that meets the needs of tinnitus sufferers.

DATA SOURCES

PubMed/MEDLINE.

REVIEW METHODS

In total, 249 relevant published reports were reviewed. Pertinent keywords and MeSH terms identified reports via PubMed and EMBASE. Acknowledged experts were consulted on ways to improve tinnitus management.

CONCLUSIONS

There may be opportunities to improve evaluation and management of patients with tinnitus using modern modes of communication and a multidisciplinary therapeutic approach.

IMPLICATIONS FOR PRACTICE

Tinnitus can adversely affect quality of life while being time-consuming and costly to evaluate and manage. Based on both personal experience and the reports of others, patients with tinnitus who choose to see a physician primarily want to know two things: (1) that the tinnitus that is so distressing will not remain at the same level of severity forever and (2) that something can be done to help cope with the tinnitus that is so annoying. Recent advancements in internet communications, social media, information technology, artificial intelligence, machine learning, holistic medical care, mind-body integrative health care, and multidisciplinary approaches in medical therapeutics may be possibly making new ways of meeting the needs of patients with tinnitus.

A Protocol to Investigate Deep Brain Stimulation for Refractory Tinnitus: From Rat Model to the Set-Up of a Human Pilot Study

BACKGROUND

Chronic tinnitus can have an immense impact on quality of life. Despite recent treatment advances, many tinnitus patients remain refractory to them. Preclinical and clinical evidence suggests that deep brain stimulation (DBS) is a promising treatment to suppress tinnitus. In rats, it has been shown in multiple regions of the auditory pathway that DBS can have an alleviating effect on tinnitus. The thalamic medial geniculate body (MGB) takes a key position in the tinnitus network, shows pathophysiological hallmarks of tinnitus, and is readily accessible using stereotaxy. Here, a protocol is described to evaluate the safety and test the therapeutic effects of DBS in the MGB in severe tinnitus sufferers.

METHODS

Bilateral DBS of the MGB will be applied in a future study in six patients with severe and refractory tinnitus. A double-blinded, randomized 2 × 2 crossover design (stimulation ON and OFF) will be applied, followed by a period of six months of open-label follow-up. The primary focus is to assess safety and feasibility (acceptability). Secondary outcomes assess a potential treatment effect and include tinnitus severity measured by the Tinnitus Functional Index (TFI), tinnitus loudness and distress, hearing, cognitive and psychological functions, quality of life, and neurophysiological characteristics.

DISCUSSION

This protocol carefully balances risks and benefits and takes ethical considerations into account. This study will explore the safety and feasibility of DBS in severe refractory tinnitus, through extensive assessment of clinical and neurophysiological outcome measures. Additionally, important insights into the underlying mechanism of tinnitus and hearing function might be revealed.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03976908 (6 June 2019).

Integrative Treatment for Tinnitus Combining Repeated Facial and Auriculotemporal Nerve Blocks With Stimulation of Auditory and Non-auditory Nerves

Background

Tinnitus is a prevalent condition (&gt;10% of the population) affecting the quality of life of 0.5–3% of the population. Although several treatments have been proposed, most of these lack evidence of efficacy in the treatment of chronic tinnitus. Thus, we aimed to evaluate an integrative treatment strategy for subacute and chronic tinnitus.

Methods

This retrospective chart review study included 55 patients with tinnitus (subacute, n = 15; chronic, n = 40) who underwent repeated nerve blocks after stimulation of the trigeminal (V) and facial (VII) nerves to modulate the auditory and non-auditory nervous systems via the vestibulocochlear (VIII) cranial nerve pathways. We used a simplified smiley tinnitus-visual analog scale (T-VAS) with scores ranging from 0 to 10 combining the effect of tinnitus loudness, distress, and quality of life as the outcome measure to evaluate the efficacy of our treatment method. Statistical analyses were performed using SPSS (version 18.0, SPSS Inc., Chicago, IL, United States), one-way and two-way analysis of variance.

Results

In more than 87.5% of patients (14/15 subacute, 35/40 chronic), tinnitus disappeared or had significantly reduced by the end of the treatment. The mean T-VAS score reduced significantly from 7.13 to 0.60 in the subacute group and from 7.73 to 1.53 in the chronic group by the end of treatment (p &lt; 0.05). The benefits were maintained after treatment cessation and at the 1-year follow-up. The average number of treatment procedures was 9.8 ± 3.589 (range, 5–15) in the subacute group and 9.775 ± 3.717 (range, 5–18) in the chronic group.

Conclusion

Our results show that the proposed integrative approach is highly effective in treating subacute and chronic tinnitus and represents a promising therapeutic approach.

Specific brain network predictors of interventions with different mechanisms for tinnitus patients

BACKGROUND

The aberrant brain network that gives rise to the phantom sound of tinnitus is believed to determine the effectiveness of tinnitus therapies involving neuromodulation with repetitive transcranial magnetic stimulation (rTMS) and sound therapy utilizing tailor-made notch music training (TMNMT). To test this hypothesis, we determined how effective rTMS or TMNMT were in ameliorating tinnitus in patients with different functional brain networks.

METHODS

Resting-state functional MRI was used to construct brain functional networks in patients with tinnitus (41 males/45 females, mean age 49.53±11.19 years) and gender-matched healthy controls (22 males/35 females, mean age 46.23±10.23 years) with independent component analysis (ICA). A 2 × 2 analysis of variance with treatment outcomes (Effective group, EG/Ineffective group, IG) and treatment types (rTMS/TMNMT) was used to test the interaction between outcomes and treatment types associated with functional network connections (FNCs).

FINDINGS

The optimal neuroimaging indicator for responding to rTMS (AUC 0.804, sensitivity 0.700, specificity 0.913) was FNCs in the salience network-right frontoparietal network (SN-RFPN) while for responding to TMNMT (AUC 0.764, sensitivity 0.864, specificity 0.667) was the combination of FNCs in the auditory network- salience network (AUN-SN) and auditory network-cerebellar network (AUN-CN).

INTERPRETATION

Tinnitus patients with higher FNCs in the SN-RFPN is associated with a recommendation for rTMS whereas patients with lower FNCs in the AUN-SN and AUN-CN would suggest TMNMT as the better choice. These results indicate that brain network-based measures aid in the selection of the optimal form of treatment for a patient contributing to advances in precision medicine.

FUNDING

Yuexin Cai is supported by Key R&D Program of Guangdong Province, China (Grant No. 2018B030339001), National Natural Science Foundation of China (82071062), Natural Science Foundation of Guangdong province (2021A1515012038), the Fundamental Research Funds for the Central Universities (20ykpy91), and Sun Yat-Sen Clinical Research Cultivating Program (SYS-Q-201903). Yu-Chen Chen is supported by Medical Science and Technology Development Foundation of Nanjing Department of Health (No. ZKX20037), and Natural Science Foundation of Jiangsu Province (No. BK20211008).

[Principles of diagnosis and treatment of tinnitus]

Tinnitus is one of the most common otological symptoms and can be defined as the conscious perception of sound lasting more than 5 minutes in the absence of an external auditory stimulus. Based on the review of articles, a comparative analysis of modern methods of diagnosis and treatment of tinnitus was carried out in order to substantiate the most effective and promising algorithms for providing care to patients. Diagnosis of tinnitus includes taking anamnesis, assessing the severity of tinnitus using questionnaires, otoscopy, hearing examination, and performing additional tests. In case of secondary murmur, etiotropic therapy should be started as soon as possible to prevent hearing loss and other complications. For primary noise, the most effective treatments are cognitive-behavioral therapy, tinnitus maskers and sound therapy, transcutaneous electrical stimulation, and biofeedback. Magnetic stimulation, invasive neuromodulation, drug therapy have a lower level of effectiveness and evidence base.

Evaluation of Spin in the Abstracts of Systematic Reviews and Meta-Analyses Focused on Tinnitus

HYPOTHESIS

The objective was to investigate the prevalence of spin in abstracts of systematic reviews and meta-analyses covering the treatment of tinnitus. We hypothesized that spin would be present in these articles and a significant relationship would exist between spin usage and extracted study characteristics.

BACKGROUND

Spin, the misrepresentation of study findings, can alter a clinician's interpretation of a study's results, potentially affecting patient care. Previous work demonstrates that spin is present in abstracts of randomized clinical trials.

METHODS

Using a cross-sectional analysis, we conducted a systematic search using MEDLINE and Embase databases on June 2, 2020, for systematic reviews focused on tinnitus treatment. Investigators performed screening and data extraction in a masked, duplicate fashion.

RESULTS

Forty systematic reviews met inclusion criteria, and spin was identified in four of them. Spin in abstracts most frequently occurred when conclusions claimed the beneficial effect of the experimental treatment despite high risk of bias in primary studies (n = 3). The other form of spin found was the conclusion claims safety based on nonstatistically significant results with a wide confidence interval (n = 1). There was no significant association between spin and any of our extracted study characteristics.

CONCLUSION

Spin was observed in 10% of abstracts of systematic reviews and meta-analyses covering the treatment of tinnitus. Although this percentage may be small, we recommend that medical journals provide a more detailed framework for abstract structure and require the inclusion of risk of bias assessment results in abstracts to prevent the incorporation of spin.

Tinnitus, Hyperacusis, Otalgia, and Hearing Loss

PURPOSE OF REVIEW

This article reviews the causes of tinnitus, hyperacusis, and otalgia, as well as hearing loss relevant for clinicians in the field of neurology.

RECENT FINDINGS

Important causes of unilateral and bilateral tinnitus are discussed, including those that are treatable or caused by serious structural or vascular causes. Concepts of hyperacusis and misophonia are covered, along with various types of neurologic disorders that can lead to pain in the ear. Hearing loss is common but not always purely otologic.

SUMMARY

Tinnitus and hearing loss are common symptoms that are sometimes related to a primary neurologic disorder. This review, tailored to neurologists who care for patients who may be referred to or encountered in neurology practice, provides information on hearing disorders, how to recognize when a neurologic process may be involved, and when to refer to otolaryngology or other specialists.

Bimodal Auditory Electrical Stimulation for the Treatment of Tinnitus: Preclinical and Clinical Studies

Tinnitus, or the phantom perception of sound, arises from pathological neural activity. Neurophysiological research has shown increased spontaneous firing rates and synchronization along the auditory pathway correlate strongly with behavioral measures of tinnitus. Auditory neurons are plastic, enabling external stimuli to be utilized to elicit long-term changes to spontaneous firing and synchrony. Pathological plasticity can thus be reversed using bimodal auditory plus nonauditory stimulation to reduce tinnitus. This chapter discusses preclinical and clinical evidence for efficacy of bimodal stimulation treatments of tinnitus, with highlights on sham-controlled, double-blinded clinical trials. The results from these studies have shown some efficacy in reducing the severity of tinnitus, based on subjective and objective outcome measures including tinnitus questionnaires and psychophysical tinnitus measurements. While results of some studies have been positive, the degree of benefit and the populations that respond to treatment vary across the studies. Directions and implications of future studies are discussed.

Animal Models of Tinnitus Treatment: Cochlear and Brain Stimulation

Neuromodulation, via stimulation of a variety of peripheral and central structures, is used to suppress tinnitus. However, investigative limitations in humans due to ethical reasons have made it difficult to decipher the mechanisms underlying treatment-induced tinnitus relief, so a number of animal models have arisen to address these unknowns. This chapter reviews animal models of cochlear and brain stimulation and assesses their modulatory effects on behavioral evidence of tinnitus and its related neural correlates. When a structure is stimulated, localized modulation, often presenting as downregulation of spontaneous neuronal spike firing rate, bursting and neurosynchrony, occurs within the brain area. Through anatomical projections and transmitter pathways, the interventions activate both auditory- and non-auditory structures by taking bottom-up ascending and top-down descending modes to influence their target brain structures. Furthermore, it is the brain oscillations that cochlear or brain stimulation evoke and connect the prefrontal cortex, striatal systems, and other limbic structures to refresh neural networks and relieve auditory, attentive, conscious, as well as emotional reactive aspects of tinnitus. This oscillatory neural network connectivity is achieved via the thalamocorticothalamic circuitry including the lemniscal and non-lemniscal auditory brain structures. Beyond existing technologies, the review also reveals opportunities for developing advanced animal models using new modalities to achieve precision neuromodulation and tinnitus abatement, such as optogenetic cochlear and/or brain stimulation.