Repetitive transcranial magnetic stimulation improve tinnitus in normal hearing patients: a double-blind controlled, clinical and neuroimaging outcome study

Focal tDCS of auditory cortex in chronic tinnitus: A randomized controlled mechanistic trial

OBJECTIVE

The goal of this pilot study was to understand how focal transcranial direct current stimulation (tDCS) targeting auditory cortex changes brain function in chronic tinnitus using magnetic resonance imaging (MRI).

METHODS

People with chronic tinnitus were randomized to active or sham tDCS on five consecutive days in this mechanistic trial (n = 10/group). Focal 4x1 tDCS (central anode, surround cathodes) targeted left auditory cortex, with single-blind 2 mA current during twenty-minute sessions. Arterial spin-labeled and blood oxygenation level dependent MRI occurred immediately before and after the first tDCS session, and tinnitus symptoms were measured starting one week before the first tDCS session and through four weeks after the final session.

RESULTS

Acute increases in cerebral blood flow and functional connectivity were noted in auditory cortex after the first active tDCS session. Reduced tinnitus loudness ratings after the final tDCS session correlated with acute change in functional connectivity between an auditory network and mediodorsal thalamus and prefrontal cortex. Reduced tinnitus intrusiveness also correlated with acute change in connectivity between precuneus and an auditory network.

CONCLUSIONS

Focal auditory-cortex tDCS can influence function in thalamus, auditory, and prefrontal cortex, which may associate with improved tinnitus.

SIGNIFICANCE

With future refinement, tDCS targeting auditory cortex could become a viable intervention for tinnitus.

Efficacy of Repetitive Transcranial Magnetic Stimulation (rTMS) for Tinnitus: A Retrospective Study

OBJECTIVE

Current studies still find insufficient evidence to support the routine use of repetitive transcranial magnetic stimulation (rTMS) in tinnitus. This study aimed to assess response of tinnitus to treatment with rTMS and identify factors influencing the overall response.

METHODS

Between January 2016 and May 2017, 199 tinnitus patients were identified from a retrospective review of the electronic patient record at the Sun Yat-sen Memorial Hospital. All patients received rTMS treatment. Their clinicodemographic profile and outcomes, including the tinnitus handicap inventory (THI) and visual analog scale (VAS) scores, were extracted for analysis.

RESULTS

Regarding the THI results, 62.3% of all patients responded to rTMS. The analysis of the VAS score revealed an overall response rate of 66.3%. Both percentages were close to the patient's subjective assessment result, of 63.8%. Patients with tinnitus of less than 1-week duration had the highest response rate to rTMS in terms of either THI/VAS scores or the patient's subjective assessment of symptoms. Tinnitus duration was recognized as a factor influencing the overall response to the treatment.

CONCLUSIONS

Repetitive transcranial magnetic stimulation treatment is effective for patients with tinnitus, but its efficacy is affected by tinnitus duration. Tinnitus patients are advised to attend for rTMS as soon as possible since therapy was more effective in those with a shorter duration of disease of less than 1 week.

Effect of Ipsilateral, Contralateral or Bilateral Repetitive Transcranial Magnetic Stimulation in Patients with Lateralized Tinnitus: A Placebo-Controlled Randomized Study

The relative benefit of ipsilateral, contralateral, and bilateral repetitive transcranial magnetic stimulation (rTMS) for tinnitus treatment remains unclear, especially for patients with lateralized tinnitus. In this study, we compared outcomes after 10 sessions of 1-Hz rTMS at 110% of resting motor threshold over a two-week period. In total, 104 right-handed patients with lateralized subjective tinnitus were randomly divided into four groups according to rTMS treatment: Left (n = 29), Right (n = 23), Bilateral (n = 30), and Sham stimulation (n = 22). Outcomes included estimates of tinnitus severity, psychological state, and psychoacoustic measures. Patients with left- or right-sided tinnitus were similarly distributed across treatment groups. There were no significant changes in outcome measures for the Right or Sham treatment groups. For the Left and Bilateral groups, tinnitus severity was significantly lower after treatment (p < 0.05). The reduction in tinnitus severity was largest for ipsilateral treatment in the Left group. The overall response rate was 56.1% for the Left group, 46.7% for the Bilateral group, 8.3% for the Right group, and 8.3% for the Sham group. For the Left and Bilateral groups, the response rate was larger for patients with left- than right-sided tinnitus. Changes in tinnitus severity were best predicted by changes in anxiety, depression, and the loudness of the tinnitus. The results suggests that rTMS on the left temporoparietal cortex is more effective for patients with left-sided than with right-sided tinnitus.

Evaluating the efficacy of hearing aids for tinnitus therapy - A Positron emission tomography study

Brain imaging studies have revealed neural changes in chronic tinnitus patients that are not restricted to auditory brain areas; rather, the engagement of limbic system structures, attention and memory networks are has been noted. Hearing aids (HA) provide compensation for comorbid hearing loss and may decrease tinnitus-related perception and annoyance. Using resting state positron emission tomography our goal was to analyze metabolic and functional brain changes after six months of effective HA use by patients with chronic tinnitus and associated sensorineural hearing loss. 33 age and hearing loss matched participants with mild/moderate hearing loss were enrolled in this study: 19 with tinnitus, and 14 without tinnitus. Participants with tinnitus of more than 6 months with moderate/severe Tinnitus Handicap Inventory (THI) and Visual Analogue Scale (VAS) scores composed the tinnitus group. A full factorial 2X2 ANOVA was conducted for imaging analysis, with group (tinnitus and controls) and time point (pre-intervention and post-intervention) as factors. Six months after HA fitting, tinnitus scores reduced statistically and clinically. Analysis revealed increased glycolytic metabolism in the left orbitofrontal cortex, right temporal lobe and right hippocampus, and reduced glycolytic metabolism in the left cerebellum and inferior parietal lobe within the tinnitus group. The hearing loss control group showed no significant metabolic changes in the analysis. Parsing out the contribution of tinnitus independent of hearing loss, allowed us to identify areas implicated in declines in tinnitus handicap as a result of the intervention. Brain regions implicated in the present study may be part of chronic tinnitus-specific network.

An updated meta-analysis: repetitive transcranial magnetic stimulation for treating tinnitus

Objective

To undertake an updated meta-analysis to obtain more evidence from randomized controlled trials (RCTs) to assess the effect of repetitive transcranial magnetic stimulation (rTMS) for the treatment of tinnitus.

Methods

PubMed®, Embase®, Web of Science, Cochrane Database of Systematic Reviews, CBM, CNKI and Wanfang were searched for RCTs from inception up to March 2020. Studies meeting the eligibility criteria were included in the meta-analysis. The mean difference was calculated and the effect size was evaluated using a Z test.

Results

The analysis included 12 randomized sham-controlled clinical trials with a total of 717 participants. Active rTMS was superior to sham rTMS in terms of the short-term and long-term effects (6 months) on the tinnitus handicap inventory scores, but an immediate effect was not significant. There was no significant immediate effect on the tinnitus questionnaire (TQ) and Beck depression inventory (BDI) scores.

Conclusions

This meta-analysis demonstrated that rTMS improved tinnitus-related symptoms, but the TQ and BDI scores demonstrated little immediate benefit. Future research should be undertaken on large samples in multi-centre settings with longer follow-up durations.

Association of Central Noninvasive Brain Stimulation Interventions With Efficacy and Safety in Tinnitus Management: A Meta-analysis

Importance

Tinnitus has a prevalence of 10% to 25% and is frequently associated with numerous complications, such as neuropsychiatric disease. Traditional treatments have failed to meet the needs of patients with tinnitus. Noninvasive brain stimulation (NIBS) can focally modify cortical functioning and has been proposed as a strategy for reducing tinnitus severity. However, the results have been inconclusive.

Objective

To evaluate the association between different central NIBS therapies and efficacy and acceptability for treatment of tinnitus.

Data Sources

ClinicalKey, Cochrane CENTRAL, Embase, ProQuest, PubMed, ScienceDirect, and Web of Science databases were searched from inception to August 4, 2019. No language restriction was applied. Manual searches were performed for potentially eligible articles selected from the reference lists of review articles and pairwise meta-analyses.

Study Selection

Randomized clinical trials (RCTs) examining the central NIBS method used in patients with unilateral or bilateral tinnitus were included in the current network meta-analysis. The central NIBS method was compared with sham, waiting list, or active controls. Studies that were not clinical trials or RCTs and did not report the outcome of interest were excluded.

Data Extraction and Synthesis

Two authors independently screened the studies, extracted the relevant information, and evaluated the risk of bias in the included studies. In cases of discrepancy, a third author became involved. If manuscript data were not available, the corresponding authors or coauthors were approached to obtain the original data. This network meta-analysis was based on the frequentist model.

Main Outcomes and Measures

The primary outcome was change in the severity of tinnitus. Secondary outcomes were changes in quality of life and the response rate related to the NIBS method in patients with tinnitus.

Results

Overall, 32 unique RCTs were included with 1458 unique participants (mean female proportion, 34.4% [range, 0%-81.2%]; mean age, 49.6 [range, 40.0-62.8] years; median age, 49.8 [interquartile range, 48.1-52.4] years). The results of the network meta-analysis revealed that cathodal transcranial direct current stimulation over the left dorsolateral prefrontal cortex combined with transcranial random noise stimulation over the bilateral auditory cortex was associated with the greatest improvement in tinnitus severity (standardized mean difference [SMD], -1.89; 95% CI, -3.00 to -0.78) and quality of life (SMD, -1.24; 95% CI, -2.02 to -0.45) compared with the controls. Improvement in tinnitus severity ranked more favorably for continuous theta-burst stimulation (cTBS) over both auditory cortices (SMD, -0.79; 95% CI = -1.57 to -0.01) than cTBS over only the left auditory cortex (SMD, -0.30; 95% CI, -0.87 to 0.28), compared with controls. Repetitive transcranial magnetic stimulation with priming had a superior beneficial association with tinnitus severity compared with the strategies without priming. None of the investigated NIBS types had a significantly different dropout rate compared with that of the control group.

Conclusions and Relevance

This network meta-analysis suggests a potential role of NIBS interventions in tinnitus management. Future large-scale RCTs focusing on longer follow-up and different priming procedure NIBS are warranted to confirm these findings.

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.

Non-invasive neuromodulation for tinnitus: A meta-analysis and modeling studies

BACKGROUND

Patients with tinnitus often have poor quality of life, as well as severe anxiety and depression. New approaches to treat tinnitus are needed.

OBJECTIVE

Evaluate the effects of non-invasive neuromodulation on tinnitus through a metaanalysis and modeling study. The main hypothesis was that real as compared to sham neuromodulation that decreases tinnitus will modulate regions in line with the neurobiological models of tinnitus.

METHODS AND RESULTS

The systematic review, conducted from Pubmed, Cochrane and PsycINFO databases, showed that active as compared to sham repetitive transcranial magnetic stimulation (rTMS) reduced tinnitus, but active and sham transcranial direct current stimulation did not significantly differ. Further, rTMS over the auditory cortex was the most effective protocol. The modeling results indicate that this rTMS protocol elicited the strongest electric fields in the insula. Also, rTMS was particularly beneficial in women. Finally, the placebo effects were highly variable, highlighting the importance of conducting sham-controlled trials.

CONCLUSION

In sum, neuromodulation protocols that target the auditory cortex and the insula may hold clinical potential to treat tinnitus.

Assessment of the Effectiveness of Transcranial Magnetic Stimulation in Subjective Tinnitus

Introduction  Increases in spontaneous activity in the neurons of the auditory cortex are presumed as the pathophysiology of tinnitus.

Objective  To investigate the effectiveness of transcranial magnetic stimulation (TMS) in the treatment of tinnitus.

Methods  A total of 62 patients between the ages of 22 and 74 with chronic subjective tinnitus were enrolled in the study. The inclusion criteria were normal findings on an otolaryngologic examination and normal ranges of complete blood count, routine biochemical parameter levels, thyroid function, air-bone gap on pure-tone audiometry, and middle-ear pressure and stapedial reflex on tympanometry. The patients were randomized into 2 groups: 40 patients were placed in the treatment for TMS (tTMS) group, and the rest (22 patients) were placed in the sham TMS group. The frequency and severity of the tinnitus, as well as the tinnitus handicap inventory (THI) score of each patient were measured before and one month after the treatment, and the values were statistically evaluated.

Results  We observed a statistically significant improvement in the tTMS group ( p  < 0.05 and p  < 0.05 respectively) regarding the THI and tinnitus severity scores. The sham TMS group showed no significant improvement in terms of the THI ( p  > 0.05). However, the tinnitus severity showed a significant increase in this group ( p  < 0.05). The comparison of differences in the changes in the THI and the tinnitus severity scores showed a significant statistical improvement in the tTMS group compared with the sham TMS group ( p  < 0.05 and p  < 0.05 respectively).

Conclusion  Transcranial magnetic stimulation was found to be effective in the treatment of tinnitus, and may be adopted as a treatment for tinnitus after further comprehensive studies.

Repetitive transcranial magnetic stimulation on chronic tinnitus: a systematic review and meta-analysis

BACKGROUND

Although the clinical efficacy and safety of repetitive transcranial magnetic stimulation (rTMS) in the treatment of chronic tinnitus have been frequently examined, the results remain contradictory. Therefore, we performed a systematic review and meta-analysed clinical trials examining the effects of rTMS to evaluate its clinical efficacy and safety.

METHODS

Studies of rTMS for chronic tinnitus were retrieved from PubMed, Embase, and Cochrane Library through April 2020. Review Manager 5.3 software was employed for data synthesis, and Stata 13.0 software was used for analyses of publication bias and sensitivity.

RESULTS

Twenty-nine randomized studies involving 1228 chronic tinnitus patients were included. Compared with sham-rTMS, rTMS exhibited significant improvements in the tinnitus handicap inventory (THI) scores at 1 week (mean difference [MD]: - 7.92, 95% confidence interval [CI]: - 14.18, - 1.66), 1 month (MD: -8.52, 95% CI: - 12.49, - 4.55), and 6 months (MD: -6.53, 95% CI: - 11.406, - 1.66) post intervention; there were significant mean changes in THI scores at 1 month (MD: -14.86, 95% CI: - 21.42, - 8.29) and 6 months (MD: -16.37, 95% CI: - 20.64, - 12.11) post intervention, and the tinnitus questionnaire (TQ) score at 1 week post intervention (MD: -8.54, 95% CI: - 15.56, - 1.52). Nonsignificant efficacy of rTMS was found regarding the THI score 2 weeks post intervention (MD: -1.51, 95% CI: - 13.42, - 10.40); the mean change in TQ scores 1 month post intervention (MD: -3.67, 95% CI: - 8.56, 1.22); TQ scores 1 (MD: -8.97, 95% CI: - 20.41, 2.48) and 6 months (MD: -7.02, 95% CI: - 18.18, 4.13) post intervention; and adverse events (odds ratios [OR]: 1.11, 95% CI: 0.51, 2.42). Egger's and Begg's tests indicated no publication bias (P = 0.925).

CONCLUSION

This meta-analysis demonstrated that rTMS is effective for chronic tinnitus; however, its safety needs more validation. Restrained by the insufficient number of included studies and the small sample size, more large randomized double-blind multi-centre trials are needed for further verification.

Dual-site rTMS is More Effective than Single-site rTMS in Tinnitus Patients: A Blinded Randomized Controlled Trial

Repetitive transcranial magnetic stimulation (rTMS) has been proposed as an alternative option for treating tinnitus. rTMS is a noninvasive method in which repetitive magnetic stimulation is applied to the cortex; it is considered a therapeutic strategy that modulates the loudness of tinnitus. In this study, we performed a double-blind randomized clinical trial to compare the outcome of tinnitus treatment among (1) dual-site (auditory + prefrontal) rTMS stimulation, (2) auditory cortex only rTMS stimulation (AC), and (3) sham stimulation. The left primary auditory cortex and left dorsolateral prefrontal cortex (DLPFC) were targeted independently of handedness or tinnitus laterality. Dual-site and auditory only groups were treated with a total of 12,000 pulses, 2000 pulses over the AC and 1000 pulses over the DLPFC (group 1), 3000 pulses over the AC only (group 2), and daily for 4 consecutive days. Dual-site group exhibited a significantly better ΔTinnitus Handicap Inventory (ΔTHI) score at 4, 8 weeks and 12 weeks after rTMS treatments compared with pre-treatment. However, there was no effect in the auditory only group. Also, there was no effect in sham group when THI scores were compared with that of the pre-treatment. These results are in line with the former studies that reported a better treatment effect by multiple site rTMS.

Dorsomedial Prefrontal Cortex Repetitive Transcranial Magnetic Stimulation for Tinnitus: Promising Results of a Blinded, Randomized, Sham-Controlled Study

OBJECTIVES

Tinnitus is the perception of sound in ears or head without corresponding external stimulus. Despite the great amount of literature concerning tinnitus treatment, there are still no evidence-based established treatments for curing or for effectively reducing tinnitus intensity. Sham-controlled studies revealed beneficial effects using repetitive transcranial magnetic stimulation (rTMS). Still, results show moderate, temporary improvement and high individual variability. Subcallosal area (ventral and dorsomedial prefrontal and anterior cingulate cortices) has been implicated in tinnitus pathophysiology. Our objective is to evaluate the use of bilateral, high frequency, dorsomedial prefrontal cortex (DMPFC) rTMS in treatment of chronic subjective tinnitus.

DESIGN

Randomized placebo-controlled, single-blinded clinical trial. Twenty sessions of bilateral, 10 Hz rTMS at 120% of resting motor threshold of extensor hallucis longus were applied over the DMPFC. Fourteen patients underwent sham rTMS and 15 were submitted to active stimulation. Tinnitus Handicap Inventory (THI), visual analog scale, and tinnitus loudness matching were obtained at baseline and on follow-up visits. The impact of intervention on outcome measures was evaluated using mixed-effects restricted maximum likelihood regression model for longitudinal data.

RESULTS

A difference of 11.53 points in the THI score was found, favoring the intervention group (p = 0.05). The difference for tinnitus loudness matching was of 4.46 dB also favoring the intervention group (p = 0.09).

CONCLUSIONS

Tinnitus treatment with high frequency, bilateral, DMPFC rTMS was effective in reducing tinnitus severity measured by THI and matched tinnitus loudness when compared to sham stimulation.

Low-Frequency Repetitive Transcranial Magnetic Stimulation for the Treatment of Chronic Tinnitus: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background

Chronic tinnitus affects approximately 10-15% of the population. Low-frequency repetitive transcranial magnetic stimulation (rTMS) has been considered as a promising and well-tolerated therapeutic strategy for chronic tinnitus. However, a recent large-scale multicenter clinical trial showed a negative result.

Objective

This systematic review is aimed at assessing the efficacy and safety of low-frequency rTMS in chronic tinnitus.

Methods

We searched PubMed, Embase, and Cochrane Library for randomized controlled studies of rTMS treatment of chronic tinnitus. A pooled analysis of standardized mean difference (SMD) was performed with 95% confidence intervals (CI).

Results

Ten RCTs involving 567 participants were included in this review. Compared with sham stimulation, rTMS showed no significant efficacy in tinnitus severity and disability measured by Tinnitus Handicap Inventory (THI) in short-term (SMD = −0.04, 95% CI -0.23 to 0.16, P = 0.72), medium-term (SMD = −0.13, 95% CI -0.43 to 0.17, P = 0.41), and long-term (SMD = −0.16, 95% CI -0.38 to 0.05, P = 0.14) follow-up. Tinnitus severity and disability measured by Tinnitus Questionnaire (TQ) also showed no significant improvement in short-term (SMD = −0.11, 95% CI -0.31 to 0.10, P = 0.30), medium-term (SMD = −0.10, 95% CI -0.37 to 0.16, P = 0.44), and long-term (SMD = −0.20, 95% CI -0.40 to 0.01, P = 0.06) follow-up. Additionally, no statistically significant difference was shown in the changes of tinnitus loudness assessed by a visual analogue scale (VAS) between rTMS and sham groups in the short-term (SMD = −0.28, 95% CI -0.59 to 0.02, P = 0.07), medium-term (SMD = −0.26, 95% CI -0.59 to 0.07, P = 0.13), and long-term (SMD = −0.20, 95% CI -0.53 to 0.13, P = 0.24) follow-up. Few mild or moderate adverse events were observed in both the rTMS and sham groups.

Conclusion

Low-frequency rTMS is well tolerated but not effective in treating chronic tinnitus based on the current analysis of pooled data. Further studies with modified and uniform protocols are required to investigate the potential benefit of rTMS in chronic tinnitus.

RTMS parameters in tinnitus trials: a systematic review

Over the past few years extensive body of research was produced investigating the effects of repetitive transcranial magnetic stimulation (rTMS) for the treatment of chronic tinnitus with heterogeneous results. This heterogeneity is exemplified by two recently published large-scale clinical trials reporting different outcomes. Technical aspects of rTMS were suspected as a potential source for this incongruency. The aim of this systematic review is to examine the overall efficacy as well as to identify possible technical factors relevant for the effectiveness of rTMS tinnitus trials. Via a literature search appropriate original research papers were identified and rTMS parameters were extracted from each study arm for subsequent statistical analysis with respect to observed effects (significant vs. not significant pre-post rTMS effects). Our findings indicate that verum rTMS is superior to sham rTMS as demonstrated by the proportion of significant pre-post contrasts. Some relevant rTMS parameters (e.g., pulse waveform) are not reported. Lower rTMS stimulation intensity was associated with significant effects in verum rTMS arms. An additional stimulation of the DLPFC to the temporal cortex was not found to promote efficacy. Future research should consider differential effects of rTMS induced by technical parameters and strive for an exhaustive reporting of relevant rTMS parameters.

Neural metabolic activity in idiopathic tinnitus patients after repetitive transcranial magnetic stimulation

BACKGROUND

The central mechanism of idiopathic tinnitus is related to hyperactivity of cortical and subcortical auditory and non-auditory areas. Repetitive transcranial magnetic stimulation (rTMS) is a well-tolerated, non-invasive potential treatment option for tinnitus.

AIM

To investigate the changes of neural metabolic activity after rTMS in chronic idiopathic tinnitus (IT) patients.

METHODS

Eleven patients underwent rTMS (1 Hz, 90% motor threshold, 1000 stimuli/day for consecutive 10 d) on the left temporoparietal region cortex. Tinnitus handicap inventory (THI) and visual analogue score (VAS) were assessed at baseline and posttreatment. All patients underwent ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography to evaluate the neural metabolic activity. Data were preprocessed using statistical parametric mapping and Gretna software to extract the regions of interest (ROIs). The correlation between brain areas involved and THI scores was analyzed.

RESULTS

Baseline and posttreatment parameters showed no significant difference regarding THI score (t = 1.019, P = 0.342 > 0.05) and VAS (t = 0.00, P = 1.0 > 0.05). Regions with the highest FDG uptake were the right inferior temporal gyrus (ITG), right parahippocampa gyrus (PHG), right hippocampus, rectus gyrus, left middle frontal gyrus, and right inferior frontal gyrus in IT patients. After rTMS treatment, IT patients showed increased activities in the right PHG, right superior temporal gyrus, right superior frontal gyrus, anterior insula, left inferior parietal lobule, and left precentral gyrus, and decreased activities in the left postcentral gyrus and left ITG. The ROIs in the right parahippocampa gyrus and right superior frontal gyrus were positively correlated with THI scores (r = 0.737, P = 0.037 < 0.05; r = 0.735, P = 0.038 < 0.05).

CONCLUSION

Our study showed that 1-Hz rTMS directed to the left temporo-parietal junction resulted no statistically significant symptom alleviation. After treatment, brain areas of the limbic and prefrontal system showed high neutral metabolic activity. The auditory and non-auditory systems together will be the target for rTMS treatment.

Neuronavigated Versus Non-navigated Repetitive Transcranial Magnetic Stimulation for Chronic Tinnitus: A Randomized Study

Repetitive transcranial magnetic stimulation (rTMS) has shown variable effect on tinnitus. A prospective, randomized 6-month follow-up study on parallel groups was conducted to compare the effects of neuronavigated rTMS to non-navigated rTMS in chronic tinnitus. Forty patients (20 men, 20 women), mean age of 52.9 years (standard deviation [ SD] = 11.7), with a mean tinnitus duration of 5.8 years ( SD = 3.2) and a mean tinnitus intensity of 62.2/100 ( SD = 12.8) on Visual Analog Scale (VAS 0-100) participated. Patients received 10 sessions of 1-Hz rTMS to the left temporal area overlying auditory cortex with or without neuronavigation. The main outcome measures were VAS scores for tinnitus intensity, annoyance, and distress, and Tinnitus Handicap Inventory (THI) immediately and at 1, 3, and 6 months after treatment. The mean tinnitus intensity (hierarchical linear mixed model: F3 = 7.34, p = .0006), annoyance ( F3 = 4.45, p = .0093), distress ( F3 = 5.04, p = .0051), and THI scores ( F4 = 17.30, p < .0001) decreased in both groups with non-significant differences between the groups, except for tinnitus intensity ( F3 = 2.96, p = .0451) favoring the non-navigated rTMS. Reduction in THI scores persisted for up to 6 months in both groups. Cohen's d for tinnitus intensity ranged between 0.33 and 0.47 in navigated rTMS and between 0.55 and 1.07 in non-navigated rTMS. The responder rates for VAS or THI ranged between 35% and 85% with no differences between groups ( p = .054-1.0). In conclusion, rTMS was effective for chronic tinnitus, but the method of coil localization was not a critical factor for the treatment outcome.

Combined transcranial magnetic stimulation in the treatment of chronic tinnitus

Objective

Repetitive transcranial magnetic stimulation (rTMS) is currently being tested for suppressing the symptoms of subjective chronic primary tinnitus, although its effect is controversial. The aim of this randomized double‐blinded controlled trial was to determine the effect of rTMS with unique settings for tinnitus treatment.

Methods

Fifty‐three adult patients suffering from chronic subjective unilateral or bilateral nonpulsatile primary tinnitus for at least 6 months were randomly assigned to rTMS (group 1, n = 20), sham stimulation (group 2, n = 12), or medicament therapy only (group 3, n = 21). The dorsolateral prefrontal cortex (frequency 25 Hz, 300 pulses, and 80% resting motor threshold [RMT]) on the left side and primary auditory cortex (1 Hz, 1000 pulses, 110% RMT) were stimulated on both sides in patients in group 1 for 5 consecutive days. The Tinnitus Reaction Questionnaire (TRQ), Tinnitus Handicap Questionnaire (THQ), Tinnitus Handicap Inventory (THI), Beck Depression Inventory (BDI), pure‐tone audiometry with Fowler scoring of hearing loss, and tinnitus analysis were used to evaluate tinnitus in all patients. Data were recorded the day the patient was included in the study and at 1‐ and 6‐month follow‐up.

Results

The study groups were homogenous. No significant effect of rTMS was found at 1 or 6 months based on the BDI, THQ, and TRQ scores or tinnitus masking. There was a significant but clinically irrelevant effect on the THI score after 1 and 6 months.

Interpretation

No significant effect of bilateral low‐frequency rTMS of the primary auditory cortex and high‐frequency stimulation of the left dorsolateral prefrontal cortex was demonstrated.

Neuromodulation for tinnitus treatment: an overview of invasive and non-invasive techniques

Tinnitus is defined as a perception of sound without any external sound source. Chronic tinnitus is a frequent condition that can affect the quality of life. So far, no causal cure for tinnitus has been documented, and most pharmacologic and psychosomatic treatment modalities aim to diminish tinnitus' impact on the quality of life. Neuromodulation, a novel therapeutic modality, which aims at alternating nerve activity through a targeted delivery of a stimulus, has emerged as a potential option in tinnitus treatment. This review provides a brief overview of the current neuromodulation techniques as tinnitus treatment options. The main intention is to provide updated knowledge especially for medical professionals counselling tinnitus patients in this emerging field of medicine. Non-invasive methods such as repetitive transcranial magnetic stimulation, transcranial electrical stimulation, neurofeedback, and transcutaneous vagus nerve stimulation were included, as well as invasive methods such as implanted vagus nerve stimulation and invasive brain stimulation. Some of these neuromodulation techniques revealed promising results; nevertheless, further research is needed, especially regarding the pathophysiological principle as to how these neuromodulation techniques work and what neuronal change they induce. Various studies suggest that individually different brain states and networks are involved in the generation and perception of tinnitus. Therefore, in the future, individually tailored neuromodulation strategies could be a promising approach in tinnitus treatment for achieving a more substantial and longer lasting improvement of complaints.

MRI Verification of a 10-20 Targeting Protocol Used During Transcranial Magnetic Stimulation Sessions for Tinnitus

Langguth et al. (2006) described a method for targeting primary auditory cortex (PAC) during transcranial magnetic stimulation (TMS) using the 10–20 electroencephalography system. Study aims were to measure the degree of accuracy in placing the TMS coil on the scalp overlying PAC using the 10–20 method and determine the extent to which accuracy depends on the hemisphere of the coil placement. Twelve participants underwent anatomical magnetic resonance imaging (MRI) of their head in a 3T scanner. Before imaging, a fiducial marker was placed on their scalp corresponding to the TMS coil position. MRI scans were analyzed to determine the distance from the fiducial marker to PAC for each participant. On average, the 10–20 method resulted in distances in the medial–lateral, anterior-posterior, and inferior-superior dimensions that were within a few millimeters (~ 4 mm) of each other between the left and right hemispheres. The fiducial marker was, on average, 10.4 mm superior and 10.8 mm posterior to the optimal scalp location that minimized the distance to PAC. Individual asymmetries and other systematic differences found in this study raise important considerations to keep in mind that might necessitate using an MRI-guided method of coil-positioning when targeting PAC for TMS.

The effects of repetitive transcranial magnetic stimulation in an animal model of tinnitus

Tinnitus (phantom auditory perception associated with hearing loss) can seriously affect wellbeing. Its neural substrate is unknown however it has been linked with abnormal activity in auditory pathways. Though no cure currently exists, repetitive transcranial magnetic stimulation (rTMS) has been shown to reduce tinnitus in some patients, possibly via induction of cortical plasticity involving brain derived neurotrophic factor (BDNF). We examined whether low intensity rTMS (LI-rTMS) alleviates signs of tinnitus in a guinea pig model and whether this involves changes in BDNF expression and hyperactivity in inferior colliculus. Acoustic trauma was used to evoke hearing loss, central hyperactivity and tinnitus. When animals developed tinnitus, treatment commenced (10 sessions of 10 minutes 1 Hz LI-rTMS or sham over auditory cortex over 14 days). After treatment ceased animals were tested for tinnitus, underwent single-neuron recordings in inferior colliculus to assess hyperactivity and samples from cortex and inferior colliculus were taken for BDNF ELISA. Analysis revealed a significant reduction of tinnitus after LI-rTMS compared to sham, without a statistical significant effect on BDNF levels or hyperactivity. This suggests that LI-rTMS alleviates behavioural signs of tinnitus by a mechanism independent of inferior colliculus hyperactivity and BDNF levels and opens novel therapeutic avenues for tinnitus treatment.

Repetitive transcranial magnetic stimulation improves both hearing function and tinnitus perception in sudden sensorineural hearing loss patients

The occurrence of sudden sensorineural hearing loss (SSHL) affects not only cochlear activity but also neural activity in the central auditory system. Repetitive transcranial magnetic stimulation (rTMS) above the auditory cortex has been reported to improve auditory processing and to reduce the perception of tinnitus, which results from network dysfunction involving both auditory and non-auditory brain regions. SSHL patients who were refractory to standard corticosteroid therapy (SCT) and hyperbaric oxygen (HBO) therapy received 20 sessions of 1 Hz rTMS to the temporoparietal junction ipsilateral to the symptomatic ear (rTMS group). RTMS therapy administered in addition to SCT and HBO therapy resulted in significantly greater recovery of hearing function and improvement of tinnitus perception compared SCT and HBO therapy without rTMS therapy. Additionally, the single photon emission computed tomography (SPECT) measurements obtained in a subgroup of patients suggested that the rTMS therapy could have alleviated the decrease in regional cerebral brain flow (rCBF) in SSHL patients. RTMS appears to be an effective, practical, and safe treatment strategy for SSHL.

A Systematic Review of Eligibility and Outcomes in Tinnitus Trials

Objective

To analyze existing tinnitus treatment trials with regard to eligibility criteria, outcome measures, study quality, and external validity and to recognize the effect of patient demographics, symptom duration, severity, and otologic comorbidity on research findings to help practitioners apply them to patient encounters.

Data Sources

Systematic literature search conducted by an information specialist for development of the American Academy of Otolaryngology—Head and Neck Surgery Foundation’s tinnitus clinical practice guideline.

Review Methods

Articles were assessed for eligibility with the PRISMA protocol (Preferred Reporting Items for Systematic Reviews and Meta-analyses) and data extracted by 2 independent investigators. Studies were assessed for methodological quality, inclusion and exclusion criteria, patient demographics, and outcome measures.

Results

A total of 147 randomized trials met inclusion criteria. Nearly all studies took place in a specialist setting. More than 50% did not explicitly define tinnitus, and 44% used a subjective severity threshold, such as “severely disturbing.” Fifty-four percent required symptom duration of at least 6 months for study eligibility, and up to 33% excluded patients with “organic” hearing loss or otologic conditions. Mean age was 52.2 years, and median follow-up was 3 months. Only 20% had a low risk of bias.

Conclusion

Randomized trials of tinnitus interventions are most applicable to older adults with tinnitus lasting ≥6 months who are evaluated in specialty settings. High risk of bias, short follow-up, and outcome reporting raise concerns about the validity of findings and may influence how clinicians apply trial results to individual patients and establish treatment expectations, thus demonstrating the need for further quality research in this field.

The effect of noninvasive brain stimulation on neural connectivity in Tinnitus: A randomized trial

OBJECTIVES/HYPOTHESIS

To explore neural connectivity changes associated with repetitive transcranial magnetic stimulation (rTMS) to the temporoparietal junction for patients with bothersome tinnitus.

STUDY DESIGN

Randomized, double-blind, controlled clinical trial.

METHODS

Thirty patients with subjective, nonpulsatile tinnitus for 6 months duration or longer and a score of 36 or greater on the Tinnitus Handicap Inventory completed the study. Participants were randomized to receive either sham or active treatment with rTMS to the temporoparietal junction for either 2 or 4 weeks of therapy. Participants underwent resting state functional connectivity magnetic resonance imaging before therapy and immediately following treatment. Functional connectivity changes between active and sham treatment groups were compared using regions of interest in auditory, default mode, ventral attention, and executive attention networks.

RESULTS

Sixteen patients received active rTMS treatment; 14 patients received sham treatment. There were no differences between the active and sham groups in baseline functional connectivity. Neither treatment with rTMS nor sham therapy resulted in statistically significant functional connectivity changes in the examined brain networks.

CONCLUSIONS

The analysis did not identify any changes in neural connectivity following treatment in patients with bothersome tinnitus. These results are consistent with our findings of lack of symptom changes previously reported in the same group of patients. Measures of neural connectivity may inform future work using rTMS to better understand the possible benefits of neural stimulation for tinnitus.

LEVEL OF EVIDENCE

1b. Laryngoscope, 126:1201-1206, 2016.

Reduction of cortical excitability and increase of thalamic activity in a low-frequency rTMS treatment for chronic tinnitus

Low-frequency repetitive transcranial magnetic stimulation (rTMS) has received increasing attention for the treatment of tinnitus, but its therapeutic mechanisms are unclear. We performed low-frequency rTMS treatment for a patient with chronic tinnitus and examined changes of cortical excitability and cerebral blood flow using paired-pulse TMS and single-photon emission computed tomography. After the rTMS treatment, tinnitus loudness was decreased, cortical excitability was reduced, and blood flow in the thalamus was increased. Our results suggest that low-frequency rTMS treatment reduces tinnitus loudness by an inhibitory effect on the cortical excitability and a remote activation effect on the thalamus through the corticothalamic networks.

Cervical epidural steroid injection for refractory somatic tinnitus

Somatic tinnitus is a common disorder, yet few treatments described in the literature have demonstrated strong efficacy. We report a case of a 61-year-old male with refractory somatic tinnitus, temporally related to a prior bacterial otitis media, wherein auditory symptoms were successfully treated with cervical epidural injections of long-acting corticosteroid. We discuss the proposed mechanism of somatic tinnitus and the means by which neuraxial steroids may inhibit somatic tinnitus symptoms.

Combined Central and Peripheral Stimulation for Treatment of Chronic Tinnitus

Background. Tinnitus is a common untreatable condition that originates from central maladaptive plasticity initiated by peripheral injury. Repetitive transcranial magnetic stimulation (rTMS), direct cochlear low-level laser therapy (LLLT), and acupuncture were tried for tinnitus treatment, but the results of these methods were clinically unsatisfactory. Objective. This study aimed to test the combined effect of the 3 methods targeting both peripheral and central auditory areas as a new therapeutic strategy for tinnitus. Methods. For this, 30 patients were randomized to 3 equal groups receiving 3 different interventions: inhibitory rTMS to the left auditory cortex, LLLT (which includes a combination of direct cochlear LLLT and laser acupuncture) to the affected ear(s), and finally, a combination of rTMS and LLLT. The Tinnitus Handicap Inventory (THI) and Visual Analogue Scale (VAS) were assessed before, immediately after, and at 2 weeks and 4 weeks after 10 consecutive every-other-day sessions for each intervention type. Results. We found that combined stimulation was effective in tinnitus treatment. This effect remained for 4 weeks after the end of the treatment. However, each of rTMS and LLLT alone had no significant effect. Repeated-measures ANOVA showed a significant effect of Time and Time × Intervention interaction for THI and VAS scores. The post hoc t test for different time points per intervention revealed a significant difference between baseline and all postintervention measurements of both THI and VAS for the combination intervention. Conclusion. Combined central rTMS and peripheral LLLT is more beneficial as a new method for management of tinnitus rather than these two used separately.

Use of cortical stimulation in neuropathic pain, tinnitus, depression, and movement disorders

Medical treatment must strike a balance between benefit and risk. As the field of neuromodulation develops, decreased invasiveness, in combination with maintenance of efficacy, has become a goal. We provide a review of the history of cortical stimulation from its origins to the current state. The first part discusses neuropathic pain and the nonpharmacological treatment options used. The second part covers transitions to tinnitus, believed by many to be another deafferentation disorder, its classification, and treatment. The third part focuses on major depression. The fourth section concludes with the discussion of the use of cortical stimulation in movement disorders. Each part discusses the development of the field, describes the current care protocols, and suggests future avenues for research needed to advance neuromodulation.

Evidence-based guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS)

A group of European experts was commissioned to establish guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS) from evidence published up until March 2014, regarding pain, movement disorders, stroke, amyotrophic lateral sclerosis, multiple sclerosis, epilepsy, consciousness disorders, tinnitus, depression, anxiety disorders, obsessive-compulsive disorder, schizophrenia, craving/addiction, and conversion. Despite unavoidable inhomogeneities, there is a sufficient body of evidence to accept with level A (definite efficacy) the analgesic effect of high-frequency (HF) rTMS of the primary motor cortex (M1) contralateral to the pain and the antidepressant effect of HF-rTMS of the left dorsolateral prefrontal cortex (DLPFC). A Level B recommendation (probable efficacy) is proposed for the antidepressant effect of low-frequency (LF) rTMS of the right DLPFC, HF-rTMS of the left DLPFC for the negative symptoms of schizophrenia, and LF-rTMS of contralesional M1 in chronic motor stroke. The effects of rTMS in a number of indications reach level C (possible efficacy), including LF-rTMS of the left temporoparietal cortex in tinnitus and auditory hallucinations. It remains to determine how to optimize rTMS protocols and techniques to give them relevance in routine clinical practice. In addition, professionals carrying out rTMS protocols should undergo rigorous training to ensure the quality of the technical realization, guarantee the proper care of patients, and maximize the chances of success. Under these conditions, the therapeutic use of rTMS should be able to develop in the coming years.

Structural brain changes following left temporal low-frequency rTMS in patients with subjective tinnitus

Repetitive transcranial magnetic stimulation (rTMS) of the temporal cortex has been used to treat patients with subjective tinnitus. While rTMS is known to induce morphological changes in healthy subjects, no study has investigated yet whether rTMS treatment induces grey matter (GM) changes in tinnitus patients as well, whether these changes are correlated with treatment success, and whether GM at baseline is a useful predictor for treatment outcome. Therefore, we examined magnetic resonance images of 77 tinnitus patients who were treated with rTMS of the left temporal cortex (10 days, 2000 stimuli/day, 1 Hz). At baseline and after the last treatment session high-resolution structural images of the brain were acquired and tinnitus severity was assessed. For a subgroup of 41 patients, additional brain scans were done after a follow-up period of 90 days. GM changes were analysed by means of voxel based morphometry. Transient GM decreases were detectable in several brain regions, especially in the insula and the inferior frontal cortex. These changes were not related to treatment outcome though. Baseline images correlated with change in tinnitus severity in the frontal cortex and the lingual gyrus, suggesting that GM at baseline might hold potential as a possible predictor for treatment outcome.

Efficacy of different protocols of transcranial magnetic stimulation for the treatment of tinnitus: Pooled analysis of two randomized controlled studies

OBJECTIVES

Tinnitus is related to alterations in neuronal activity of auditory and nonauditory brain areas. Targeted modulation of these areas by repetitive transcranial magnetic stimulation (rTMS) has been proposed as a new therapeutic approach for chronic tinnitus.

METHODS

Two randomized, double-blind, parallel-group, controlled clinical trials were performed subsequently and pooled for analysis. A total of 192 tinnitus patients were randomly allocated to receive 10 stimulation sessions of either sham rTMS, PET-based neuronavigated 1 Hz rTMS, 1Hz r TMS over the left auditory cortex, or combined 20 Hz rTMS over the left frontal cortex, followed by 1 Hz rTMS over the left auditory cortex.

RESULTS

rTMS treatment was well tolerated and no severe side effects were observed. All active rTMS treatments resulted in significant reduction of the TQ as compared to baseline. The comparison between treatment groups failed to reach significant differences. The number of treatment responders was higher for temporal rTMS(38%) and combined frontal and temporal rTMS (43%), as compared to sham (6%).

CONCLUSIONS

This large study demonstrates the safety and tolerability of rTMS treatment in patients with chronic tinnitus. While the overall effect did not prove superior to placebo, secondary outcome parameters argue in favour of the active stimulation groups, and specifically the combined frontal and temporal rTMS protocol.

Polarity specific suppression effects of transcranial direct current stimulation for tinnitus

Tinnitus is the perception of a sound in the absence of an external auditory stimulus and affects 10-15% of the Western population. Previous studies have demonstrated the therapeutic effect of anodal transcranial direct current stimulation (tDCS) over the left auditory cortex on tinnitus loudness, but the effect of this presumed excitatory stimulation contradicts with the underlying pathophysiological model of tinnitus. Therefore, we included 175 patients with chronic tinnitus to study polarity specific effects of a single tDCS session over the auditory cortex (39 anodal, 136 cathodal). To assess the effect of treatment, we used the numeric rating scale for tinnitus loudness and annoyance. Statistical analysis demonstrated a significant main effect for tinnitus loudness and annoyance, but for tinnitus annoyance anodal stimulation has a significantly more pronounced effect than cathodal stimulation. We hypothesize that the suppressive effect of tDCS on tinnitus loudness may be attributed to a disrupting effect of ongoing neural hyperactivity, independent of the inhibitory or excitatory effects and that the reduction of annoyance may be induced by influencing adjacent or functionally connected brain areas involved in the tinnitus related distress network. Further research is required to explain why only anodal stimulation has a suppressive effect on tinnitus annoyance.

Memory networks in tinnitus: a functional brain image study

Tinnitus is characterized by the perception of sound in the absence of an external auditory stimulus. The network connectivity of auditory and non-auditory brain structures associated with emotion, memory and attention are functionally altered in debilitating tinnitus. Current studies suggest that tinnitus results from neuroplastic changes in the frontal and limbic temporal regions. The objective of this study was to use Single-Photon Emission Computed Tomography (SPECT) to evaluate changes in the cerebral blood flow in tinnitus patients with normal hearing compared with healthy controls.

METHODS

Twenty tinnitus patients with normal hearing and 17 healthy controls, matched for sex, age and years of education, were subjected to Single Photon Emission Computed Tomography using the radiotracer ethylenedicysteine diethyl ester, labeled with Technetium 99 m (99 mTc-ECD SPECT). The severity of tinnitus was assessed using the "Tinnitus Handicap Inventory" (THI). The images were processed and analyzed using "Statistical Parametric Mapping" (SPM8).

RESULTS

A significant increase in cerebral perfusion in the left parahippocampal gyrus (pFWE <0.05) was observed in patients with tinnitus compared with healthy controls. The average total THI score was 50.8+18.24, classified as moderate tinnitus.

CONCLUSION

It was possible to identify significant changes in the limbic system of the brain perfusion in tinnitus patients with normal hearing, suggesting that central mechanisms, not specific to the auditory pathway, are involved in the pathophysiology of symptoms, even in the absence of clinically diagnosed peripheral changes.

Randomized Trial of Transcranial Direct Current Stimulation and Hearing Aids for Tinnitus Management

Background. The perception of sound in the absence of an external sound is tinnitus. Tinnitus can have a severe negative impact on quality of life. Objective. This trial investigated whether multisession anodal transcranial direct current stimulation (tDCS) of the left temporoparietal area would enhance sound therapy from hearing aids. Methods. Forty participants (mean age = 54 years) experiencing chronic tinnitus (minimum 2 years) completed a 7-month long double-blind randomized clinical trial. Participants were randomized into 2 groups: control receiving sham tDCS and experimental receiving tDCS. Each group underwent multisession (5 consecutive sessions with 24-hour gap) anodal tDCS (2 mA intensity and 20 minutes duration) of the left temporoparietal area, followed by hearing aid use for 6 months. The impact of tDCS and hearing aid use on tinnitus was assessed using questionnaires (primary measure: Tinnitus Functional Index) and minimum masking level measurement. Results. There was a significant reduction in the overall Tinnitus Functional Index score with time, F(2, 37) = 11.9, P = .0001, for both the groups. Similar patterns were seen for secondary measures. tDCS appeared to have a positive effect on minimum masking levels but not questionnaire responses. Conclusions. After 3 months of hearing aid use, there were significant improvements in tinnitus, which were sustained at 6 months of use. The hearing aid effects appeared independent of tDCS. Further investigations of tDCS or other neuromodulators priming the auditory system for sound therapy based tinnitus treatments are warranted.