What clinical trials currently test transcranial magnetic stimulation for tinnitus and what are their results?
Executive summary
Repetitive transcranial magnetic stimulation (rTMS/TMS) has been tested in multiple randomized controlled trials and smaller feasibility and observational studies for chronic tinnitus, but results are mixed: some trials and meta-analyses report modest benefit or superiority over sham, while large multicenter trials and other reviews report no consistent clinically meaningful effect [1] [2] [3] [4]. Heterogeneity in protocols, targets, and patient characteristics — and unresolved technical questions — explain much of the divergent literature and limit firm clinical conclusions [5] [2].
1. The headline randomized trials: promising single-site results versus large negative multicenter work
A widely cited randomized, placebo‑controlled clinical trial led by Folmer and published in JAMA Otolaryngology tested rTMS for chronic tinnitus with follow‑up out to 26 weeks and reported treatment effects that prompted follow‑up analyses of responders and predictors of benefit (trial registry NCT01104207) [6] [7] [8]. By contrast, other large randomized trials — including a multicenter low‑frequency rTMS study and the Bilateral Low‑Frequency trial reported by Hoekstra et al. — failed to show efficacy, illustrating contradictory outcomes across rigorously designed RCTs [1] [4] [2].
2. Systematic reviews and meta‑analyses: signal but noisy evidence
Multiple systematic reviews and meta‑analyses conclude that the evidence is heterogeneous: some pooled analyses find rTMS superior to sham on selected outcomes, while others emphasize inconsistent effects and call for standardized protocols and larger multisite trials before recommending rTMS broadly for tinnitus [1] [3] [9] [4]. Reviews highlight that positive findings often depend on outcome selection, follow‑up timing, and which trials are included, leaving the clinical picture ambiguous [1] [3].
3. Newer and alternative protocols: multilocus and high‑frequency approaches
Recent smaller studies and feasibility work have explored multilocus sequential stimulation (prefrontal plus auditory targets), high‑frequency protocols, and burst patterns; an observational multilocus sequential rTMS study reported significant tinnitus improvement and suggested faster benefit for patients without comorbid major depressive disorder, though outcomes were variable and sample sizes remain limited [10] [11]. A feasibility study of high‑frequency rTMS on chronic subjective tinnitus enrolled a small cohort and reported preliminary safety and signals of efficacy, but was explicitly designed to assess feasibility rather than to provide definitive efficacy evidence [12].
4. Why trials disagree: methodological and technical fracture lines
Experts flag several unresolved issues that likely drive mixed trial results: variability in coil positioning and scalp targeting, stimulation frequency and waveform, intensity, number and spacing of sessions, patient selection (age, hearing loss, tinnitus duration), and even coil current direction — all of which may change outcomes and hamper cross‑trial comparability [5] [2]. Reviews call for large‑scale, multisite trials using standardized, pre‑specified protocols and better reporting of technical parameters to determine which approaches, if any, reliably help subgroups of patients [5] [2].
5. Safety, practical notes, and the clinical takeaways
Across trials and feasibility studies, rTMS appears generally well tolerated with mainly mild adverse effects reported, but because efficacy is inconsistent and dependent on protocol and patient factors, major professional groups and systematic reviewers refrain from endorsing rTMS as a standard tinnitus treatment pending larger pragmatic trials and protocol harmonization [1] [4] [3]. Ongoing and recent institutional efforts — including VA‑sponsored trials and single‑center programs that continue to refine multilocus or extended session regimens — indicate active investigation but not yet definitive practice‑changing evidence [13] [10].
6. Bottom line
Clinical trials testing TMS for tinnitus span small feasibility cohorts, positive single‑site randomized trials, and larger negative multicenter RCTs; systematic reviews synthesize a noisy signal that can be read as modest benefit in some analyses or as overall inconclusive in others, and unresolved technical and population heterogeneity remain the primary reasons definitive proof is lacking [6] [4] [5] [9].