Auditory cortex hyperconnectivity before rTMS is correlated with tinnitus improvement

INTRODUCTION

Repetitive transcranial magnetic stimulation (rTMS) has been used as a potential treatment for tinnitus; however, its effectiveness is variable and unpredictable. We hypothesized that resting-state functional connectivity before rTMS may be correlated with rTMS treatment effectiveness.

METHODS

We applied 1-Hz rTMS to the left primary auditory (A1) and dorsolateral prefrontal cortices (DLPFC) of 10 individuals with tinnitus and 10 age-matched controls. Resting-state functional magnetic resonance imaging (fMRI) studies were performed approximately one week before rTMS. Seed-based connectivity analyses were conducted for each individual, with seed regions as rTMS target areas.

RESULTS

Compared to controls, the left superior temporal areas showed significantly increased positive connectivity with the left A1 and negative connectivity with the left DLPFC in the tinnitus group. The left frontoparietal and right cerebellar areas showed significantly increased negative connectivity with the left A1 and positive connectivity with the left DLPFC. Seed-based hyperconnectivity was correlated with tinnitus improvement (pre-rTMS vs. 2-week post-rTMS Tinnitus Handicap Inventory scores). Tinnitus improvement was significantly correlated with left A1 hyperconnectivity; however, no correlation was observed with left DLPFC connectivity. Positive rTMS outcomes were associated with significantly increased positive connectivity in bilateral superior temporal areas and significantly increased negative connectivity in bilateral frontal areas.

CONCLUSIONS

Our results suggest that oversynchronisation of left A1 connectivity before rTMS of the left A1 and DLPFC is associated with treatment effectiveness.

The Treatment Outcome of Smart Device-Based Tinnitus Retraining Therapy: Prospective Cohort Study

BACKGROUND

Tinnitus retraining therapy (TRT) is a standard treatment for tinnitus that consists of directive counseling and sound therapy. However, it is based on face-to-face education and a time-consuming protocol. Smart device-based TRT (smart-TRT) seems to have many advantages, but the efficacy of this new treatment has been questioned.

OBJECTIVE

The aim of this study was to compare the efficacy between smart-TRT and conventional TRT (conv-TRT).

METHODS

We recruited 84 patients with tinnitus. Results were compared between 42 patients who received smart-TRT and 42 control participants who received conv-TRT. An interactive smart pad application was used for directive counseling in the smart-TRT group. The smart pad application included detailed education on ear anatomy, the neurophysiological model of tinnitus, concept of habituation, and sound therapy. The smart-TRT was bidirectional: There were 17 multiple choice questions between each lesson as an interim check. The conv-TRT group underwent traditional person-to-person counseling. The primary outcome measure was the Tinnitus Handicap Inventory (THI), and the secondary outcome measure was assessed using a visual analogue scale (VAS).

RESULTS

Both treatments had a significant treatment effect, which comparably improved during the first 2 months. The best improvements in THI were -23.3 (95% CI -33.1 to -13.4) points at 3 months and -16.8 (95% CI -30.8 to -2.8) points at 2 months in the smart-TRT group and conv-TRT group, respectively. The improvements on the VAS were also comparable: smart-TRT group: -1.2 to -3.3; conv-TRT: -0.7 to -1.7.

CONCLUSIONS

TRT based on smart devices can be an effective alternative for tinnitus patients. Considering the amount of time needed for person-to-person counseling, smart-TRT can be a cost-effective solution with similar treatment outcomes as conv-TRT.

Sequential Prefrontal and Temporoparietal Repetitive Transcranial Magnetic Stimulation (rTMS) for Treatment of Tinnitus With and Without Comorbid Depression: A Case Series and Systematic Review

Background

Tinnitus distress is related to both the loudness and intrusiveness of the tinnitus percept. Treatment approaches targeting both attentional/limbic and auditory systems may better alleviate tinnitus distress than approaches targeting the auditory system alone.

Materials and Methods

Ten subjects with chronic tinnitus received sequential rTMS treatment involving: 1) excitatory stimulation administered to the left dorsolateral prefrontal cortex (DLPFC) or inhibitory stimulation administered to the right DLPFC, followed by 2) inhibitory stimulation administered to primary auditory cortex (Heschel's gyrus or HG). A systematic literature review was performed to evaluate the existing literature on sequential repetitive Transcranial Magnetic Stimulation (rTMS) treatment approaches for tinnitus. Results of the case series are interpreted in the context of tinnitus neurobiology and the extant literature.

Results

Subjects experienced a significant decrease (average 21.7%) in symptoms on the Tinnitus Functional Index (TFI). Those with tinnitus alone experienced a greater mean symptom reduction than those with comorbid MDD (27.7 vs. 17.0%, respectively). Adverse effects were transient and minor. Literature review confirmed that sequential approaches had some advantages compared to single site rTMS; in general, the addition of 1 Hz treatment at DLPFC was superior to single site rTMS in the short term (1-12 weeks), while the addition of 20 Hz treatment at DLPFC appeared superior in the long term (90-180 days).

Conclusions

Sequential rTMS approaches for the treatment of tinnitus-particularly those administering low-frequency treatment at left DLPFC-merit further investigation.

Auditory cortex hyperconnectivity before rTMS is correlated with tinnitus improvement

INTRODUCTION

Repetitive transcranial magnetic stimulation (rTMS) has been used as a potential treatment for tinnitus; however, its effectiveness is variable and unpredictable. We hypothesized that resting-state functional connectivity before rTMS may be correlated with rTMS treatment effectiveness.

METHODS

We applied 1-Hz rTMS to the left primary auditory (A1) and dorsolateral prefrontal cortices (DLPFC) of 10 individuals with tinnitus and 10 age-matched controls. Resting-state functional magnetic resonance imaging (fMRI) studies were performed approximately one week before rTMS. Seed-based connectivity analyses were conducted for each individual, with seed regions as rTMS target areas.

RESULTS

Compared to controls, the left superior temporal areas showed significantly increased positive connectivity with the left A1 and negative connectivity with the left DLPFC in the tinnitus group. The left frontoparietal and right cerebellar areas showed significantly increased negative connectivity with the left A1 and positive connectivity with the left DLPFC. Seed-based hyperconnectivity was correlated with tinnitus improvement (pre-rTMS vs. 2-week post-rTMS Tinnitus Handicap Inventory scores). Tinnitus improvement was significantly correlated with left A1 hyperconnectivity; however, no correlation was observed with left DLPFC connectivity. Positive rTMS outcomes were associated with significantly increased positive connectivity in bilateral superior temporal areas and significantly increased negative connectivity in bilateral frontal areas.

CONCLUSIONS

Our results suggest that oversynchronisation of left A1 connectivity before rTMS of the left A1 and DLPFC is associated with treatment effectiveness.

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.

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.

Transcranial direct current stimulation improves tinnitus perception and modulates cortical electrical activity in patients with tinnitus: A randomized clinical trial

OBJECTIVES

This study aims to determine whether transcranial direct current stimulation (tDCS): a) is effective in the treatment of tinnitus by decreasing its annoyance and severity; b) modulates the cortical electrical activity of such individuals.

METHODS

A double-blind, placebo-controlled clinical trial was conducted with 24 patients with tinnitus, randomized into two groups: Group 1 (n = 12) received anodal tDCS over the left temporoparietal area (LTA) and cathodal tDCS over the right dorsolateral prefrontal cortex (DLPFC) and Group 2 (n = 12) received placebo intervention. Tinnitus perception using a visual analog scale (VAS) and the Tinnitus Handicap Inventory (THI) questionnaire, in addition to electroencephalogram (EEG) was measured with eyes opened and closed at baseline and after the intervention. For the treatment, patients were subjected to five consecutive sessions of tDCS with the anodal electrode over the LTA and cathodal electrode over the right DLPFC (7 × 5 cm, 2 mA for 20 min). tDCS was turned off after 30 s in the sham group.

RESULTS

Active tDCS significantly improved tinnitus annoyance and severity. It was associated with decreased beta and theta EEG frequency bands with eyes opened and decreased alpha frequency with eyes closed. sLORETA identified changes in frequency bands in the frontal, temporoparietal, and limbic regions. Finally, there were negative correlations between baseline EEG frequency bands and tDCS-induced change in tinnitus annoyance and severity.

CONCLUSIONS

These results demonstrate that tDCS modulates the EEG activity and alleviates tinnitus perception. This effect may be related to baseline EEG activity.

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.