Dual-site transcranial direct current stimulation to treat tinnitus: a randomized controlled trial

Repeated Bilateral Transcranial Direct Current Stimulation over Auditory Cortex for Tinnitus Treatment: A Double-Blinded Randomized Controlled Clinical Trial

Transcranial direct current stimulation (tDCS) is a non-invasive and painless technique of brain neuromodulation that applies a low-intensity galvanic current to the scalp with the aim of stimulating specific areas of the brain. Preliminary investigations have indicated the potential therapeutic efficacy of multisession tDCS applied to the auditory cortex (AC) in the treatment of chronic tinnitus. The aim of this study was to explore the therapeutic effects of repeated sessions of bilateral tDCS targeting the AC on chronic tinnitus. A double-blinded randomized placebo-controlled trial was conducted on patients (n = 48) with chronic intractable tinnitus (>2 years duration). Participants were randomly allocated to two groups: one receiving tDCS (n = 26), with the anode/cathode placed over the left/right AC, and the other receiving a placebo treatment (n = 22). A 20 min daily session of 2 mA current was administered for five consecutive days per week over two consecutive weeks, employing 35 cm2 electrodes. Tinnitus handicap inventory (THI) scores, tinnitus loudness, and tinnitus distress were measured using a visual analogue scale (VAS), and were assessed before intervention, immediately after, and at one-month follow-up. Anodal tDCS significantly reduced THI from 72.93 ± 10.11 score to 46.40 ± 15.36 after the last session and 49.68 ± 14.49 at one-month follow-up in 18 out of 25 participants (p < 0.001). The risk ratio (RR) of presenting an improvement of ≥20 points in the THI after the last session was 10.8 in patients treated with tDCS. Statistically significant reductions were observed in distress VAS and loudness VAS (p < 0.001). No statistically significant differences in the control group were observed. Variables such as age, gender, duration of tinnitus, laterality of tinnitus, baseline THI scores, and baseline distress and loudness VAS scores did not demonstrate significant correlations with treatment response. Repeated sessions of bilateral AC tDCS may potentially serve as a therapeutic modality for chronic tinnitus.

Development of a Prognostic Nomogram for Modified Tinnitus Relieving Sound Therapy for Subjective Tinnitus

OBJECTIVE

We aimed to develop a modified tinnitus-relieving sound system and establish a model for predicting its treatment effects.

STUDY DESIGN

Retrospective study.

SETTING

Tinnitus Specialist Clinic of Eye & ENT Hospital, Fudan University.

METHODS

We recruited 107 patients undergoing modified tinnitus-relieving sounds between August 2020 and May 2021. Patients were divided into training (n = 75) and validation (n = 32) cohorts in a 7:3 ratio. The treatment outcome was Tinnitus Handicapped Inventory scores. Features were established using a least absolute shrinkage and selection operator-derived logistic regression model, where the selected clinical risk factors were included in the multivariate logistic regression, and a nomogram was established based on the model. The discrimination and calibration abilities of the nomogram were evaluated using the Hosmer-Lemeshow test and calibration curves. Decision curve analysis (DCA) was used to evaluate the net benefit of predictive efficacy.

RESULTS

Multivariate logistic analysis indicated that the initial Tinnitus Handicapped Inventory score (odds ratio [OR]: 1.13 [1.07-1.19], P < .001) and treatment duration (OR: 3.4 [1.34-8.62], P < .001) were positive factors for improved tinnitus. The nomogram model that included baseline Tinnitus Handicapped Inventory score and treatment duration achieved a better concordance index of 0.880. DCA revealed that the nomogram model could lead to net benefits and exhibited a wider range of threshold probabilities for the prediction of therapeutic effects.

CONCLUSION

Our study suggests that the nomogram model, including baseline Tinnitus Handicapped Inventory score and treatment duration, could achieve optimal performance in the preoperative prediction of the therapeutic effect of modified tinnitus-relieving sound.

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.

Recent Updates on Tinnitus Management

In this comprehensive review, we discuss recent updates on tinnitus evaluation and treatment. Tinnitus evaluation commences with comprehensive medical history taking and audiological evaluation, which can provide valuable insight into the nature and extent of auditory disturbances. Additionally, tinnitus evaluation includes investigation of psychosomatic comorbidities to determine the intricate interplay between psychological factors and tinnitus perception. Various therapeutic approaches are available to minimize the burden of tinnitus. Cognitive behavioral therapy reshapes negative thought patterns and behaviors that are closely associated with tinnitus-induced distress. Acceptance and commitment therapy fosters mindfulness and value-aligned actions to address emotional effects. Tinnitus retraining therapy combines counseling and sound therapy for habituation. Tailor-made notched music therapy offers customized auditory experiences for symptom relief. Hearing aids and cochlear implants compensate for hearing loss and associated stress. Both neuromodulation and neurofeedback may be potentially useful. The role of pharmacotherapy and dietary supplements remains uncertain. Physiotherapy and head-neck manipulation relieve tinnitus associated with orofacial factors. Virtual reality, smartphone applications, and photobiomodulation may serve as novel therapeutic avenues. Although promising interventions are available, further research is warranted to confirm their effectiveness and long-term effects.

Focal transcranial direct current stimulation of auditory cortex in chronic tinnitus: A randomized controlled mechanistic trial

Objective

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

Methods

People with chronic tinnitus were randomized to active or sham tDCS on five consecutive days in this pilot mechanistic trial (n=10/group). Focal 4×1 tDCS (central anode, surround cathodes) targeted left auditory cortex, with single-blind 2mA 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, noninvasive brain stimulation targeting auditory cortex could become a viable intervention for tinnitus.