Bimodal Electrical-Sound Stimulation and Auditory Training for Chronic Tonal Tinnitus

Official title

Non-Invasively Re-Training the Tinnitus Brain Using Bimodal Electrical-Sound Stimulation (NITESGON-ADT): Protocol for a Prospective, Double-Blind, Randomised Controlled Trial

Overview

This study tests whether pairing non-invasive stimulation of the greater occipital nerve (NITESGON) with an attentionally demanding auditory frequency discrimination training task reduces tinnitus loudness and tinnitus-related distress. One hundred adults with chronic tonal tinnitus will be randomised to one of four groups in a 2×2 factorial design: real versus sham NITESGON and active versus passive listening during auditory stimulation. Participants complete eight sessions across four weeks, with outcomes assessed at baseline, end of treatment, 28 days post-treatment, and 6 months post-treatment.

Detailed description

This is a single-centre, prospective, double-blind, placebo-controlled, 2×2 factorial randomised controlled trial conducted at Trinity College Dublin. The intervention combines transcutaneous electrical stimulation targeting the greater occipital nerve (NITESGON) with auditory stimulation delivered during a structured training paradigm. The two between-subjects factors are stimulation condition (real NITESGON vs sham NITESGON) and listening condition (active listening: auditory frequency discrimination training vs passive listening: visual distractor task while auditory stimuli are presented). One hundred adults with chronic tonal tinnitus will be randomised 1:1:1:1 to one of four arms. Participants complete eight sessions (two per week for four weeks). Primary outcomes-tinnitus loudness (VAS 0-100), tinnitus-related functional impact (TFI 0-100), and tinnitus handicap (THI 0-100)-and secondary outcomes are assessed at baseline (T0), end of treatment (T1), 28 days after treatment completion (T2), and 6 months after treatment completion (T3). Secondary outcomes include tinnitus psychoacoustics, extended high-frequency audiometry, speech-in-noise performance, EEG (resting-state and auditory oddball), autonomic/biomarker measures (pupillometry, heart rate, saliva), patient global impression of change, quality of life, and safety/blinding assessments.

Interventions

• Device Real NITESGON
  Real NITESGON is delivered transcutaneously via two saline-soaked sponge electrodes (35 cm² each) positioned bilaterally over the C2 dermatomes to target the greater occipital nerve. Stimulation consists of a 20 Hz sinusoidal current at 1.5 mA peak-to-peak, ramped up over 30 seconds and ramped down over 5 seconds. It is administered concurrently with the task for \~45 minutes per session, across eight sessions (2/week) over 4 weeks.
• Device Sham NITESGON
  Sham NITESGON is delivered using two saline-soaked sponge electrodes (35 cm² each) positioned bilaterally over the C2 dermatomes. The sham condition mimics real stimulation sensations via a 30-second ramp-up followed by a brief ramp-down, with no sustained current thereafter. Sham is administered concurrently with the task for \~45 minutes per session, across eight sessions (2/week) over 4 weeks.
• Behavioral Active Listening
  ADT is delivered using a three-interval, three-alternative forced-choice (3I-3AFC) frequency discrimination task. Standard tone frequencies are individually selected using ERB/critical-band spacing, centered one octave below each participant's dominant tinnitus pitch and extending to lower frequencies; the highest standard is kept below the tinnitus pitch region. Tones are presented binaurally via headphones, with presentation levels calibrated to individual audiometric thresholds and matched fo
• Behavioral Passive Listening (Control)
  VisDT uses a three-interval, three-alternative forced-choice (3I-3AFC) paradigm with Gabor patches (sinusoidal gratings windowed by a Gaussian envelope) of fixed spatial frequency (6 cycles/degree) and fixed spatial spread; on each trial, one interval contains an orientation deviant relative to the standard. During VisDT, participants attend to the visual task while concurrent binaural tones are presented passively using a predetermined, non-adaptive schedule. Auditory tones are individually cal

Primary outcome measures

• Tinnitus Loudness (Visual Analogue Scale, VAS 0-100) [Time frame: Baseline visit, end of treatment at 4 weeks, 28 days post-treatment, and 6 months post-treatment.]
• Tinnitus Functional Index (TFI, 0-100) [Time frame: Baseline visit, end of treatment at 4 weeks, 28 days post-treatment, and 6 months post-treatment.]
• Tinnitus Handicap Inventory (THI, 0-100) [Time frame: Baseline visit, end of treatment at 4 weeks, 28 days post-treatment, and 6 months post-treatment.]

Secondary outcome measures (12)

• Audiometry (Extended High-Frequency Thresholds up to 13 kHz) [Time frame: Baseline visit, end of treatment at 4 weeks, 28 days post-treatment, and 6 months post-treatment.]
• Speech-in-Noise Performance (e.g., QuickSIN) [Time frame: Baseline visit, end of treatment at 4 weeks, 28 days post-treatment, and 6 months post-treatment.]
• Patient Global Impression of Change (PGIC) [Time frame: End of treatment at 4 weeks, 28 days post-treatment, and 6 months post-treatment.]
• Quality of Life (World Health Organization Quality of Life-BREF questionnaire) [Time frame: Baseline visit, end of treatment at 4 weeks, 28 days post-treatment, and 6 months post-treatment.]
• Adverse Events (Stimulation Side-Effects Questionnaire) [Time frame: Up to 4 weeks (Sessions 1-8)]
• Tinnitus Pitch Matching [Time frame: Baseline, end of treatment at 4 weeks, 28 days post-treatment, and 6 months post-treatment.]
• Tinnitus Loudness Matching and Discomfort Levels [Time frame: Baseline visit, end of treatment at 4 weeks, 28 days post-treatment, and 6 months post-treatment.]
• Minimum Masking Level (MML) [Time frame: Baseline visit, end of treatment at 4 weeks, 28 days post-treatment, and 6 months post-treatment.]
• Resting-State EEG Spectral Power (Eyes Closed) [Time frame: Baseline visit, end of treatment (4 weeks), 28 days post-treatment, and 6 months post-treatment.]
• Resting-State EEG Functional Connectivity (Eyes Closed) [Time frame: Baseline visit, end of treatment (4 weeks), 28 days post-treatment, and 6 months post-treatment.]
• Auditory Oddball Task-Evoked Response Amplitude [Time frame: Baseline visit, end of treatment (4 weeks), 28 days post-treatment, and 6 months post-treatment.]
• Auditory Oddball Task-Evoked Response Latency [Time frame: Baseline visit, end of treatment (4 weeks), 28 days post-treatment, and 6 months post-treatment.]

Eligibility criteria

Inclusion criteria

• Adults aged 18-80 years
• Continuous subjective tinnitus for >3 months and ≤5 years
• Predominantly tonal tinnitus (unilateral or bilateral)
• Screening THI score 28-76
• Minimum Masking Level (MML) 20-80 dB HL
• No prior tinnitus neuromodulation treatment
• Able to comply with eight sessions over four weeks and follow-up assessments

Exclusion criteria

• Objective tinnitus or predominantly somatic tinnitus
• Pulsatile tinnitus
• Evidence of conductive hearing loss (abnormal otoscopy or tympanometry)
• Pure-tone audiometry exclusions: >40 dB HL at any frequency 250 Hz-1 kHz OR >80 dB HL at any frequency 2-8 kHz in either ear
• Hearing aid use initiated within the past 90 days
• Active implantable medical device (e.g., pacemaker, DBS, cochlear implant)
• LDL <30 dB SL at 500 Hz in either ear
• Diagnosis of temporomandibular joint disorder or occipital neuralgia
• Severe anxiety (STAI >120/160)
• Cognitive impairment (MMSE <25)
• Severe depressive symptoms (BDI ≥30)
• Diagnosis of Menière's disease
• Current pregnancy
• Involvement in medicolegal cases
• History of auditory hallucinations
• Current prescription of central nervous system drugs likely to alter neuromodulatory function (e.g., noradrenergic, dopaminergic, serotonergic, benzodiazepine, cholinergic, or other psychoactive medications)
• Currently enrolled in another interventional study

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Factorial

Masking

Double blind

Primary purpose

Treatment

Study locations

Ireland · 1 center

• Trinity College Institute of Neuroscience (TCIN) — Dublin

Identifiers

NCT: NCT07393880 · NITESGON-SPREC102020-46 · DRG2332

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗