Transcutaneous Auricular Vagus Nerve Stimulation Combined With Tailor-Made Notched Music Training Therapy for Chronic Subjective Tinnitus

The Tinnitus Improvement Response Rate is evaluated based on the change in Tinnitus Handicap Inventory (THI) scores. A higher score indicates greater interference of tinnitus with quality of life. Treatment response is defined as a reduction in the THI score of >7 points from the baseline assessment after 3 months of treatment, based on the internationally recognized Minimal Clinically Important Difference (MCID) threshold. Calculation Formula: Tinnitus Improvement Response Rate (%) = (Number of Responders / Total Number of Cases in the Corresponding Group) × 100%

Patients rate their current perception of tinnitus loudness on a Visual Analogue Scale (VAS) ranging from 0 to 10. A score of 0 represents "extremely faint/imperceptible" tinnitus, and 10 represents "extremely loud/intolerable" tinnitus. The outcome is reported as the change in score from Baseline.

Based on the pitch characteristics described by the patient, a test stimulus (pure tone or narrow-band noise, 0.125-8.0 kHz) is selected. Using a bracketing procedure with 2 dB steps, the loudness is matched to the patient's tinnitus perception. The outcome is measured in decibels sensation level (dB SL/HL) relative to the patient's hearing threshold.

Total number of participants who experience treatment-related adverse events. Events include auditory system-related reactions (e.g., burns, earache, hearing deterioration, worsening tinnitus) and non-auditory reactions (e.g., dizziness, headache, palpitations, vomiting) deemed related to the intervention.

The BAI requires patients to rate 21 anxiety symptoms. The raw score is converted to a standardized score using the formula Y = int(1.19x). Scores range from 0 to 63, with higher scores indicating more severe anxiety. The outcome is reported as the change in standardized score from Baseline.

The BDI consists of 21 groups of items. Scores are summed to obtain a total score ranging from 0 to 63. Higher scores indicate a more severe degree of depression. The outcome is reported as the change in total score from Baseline.

The PSQI assesses sleep quality. The Global Score ranges from 0 to 21, where a higher score indicates poorer sleep quality. The outcome is reported as the change in Global Score from Baseline.

Evaluated based on the Tinnitus Handicap Inventory (THI). A "Responder" is defined as a participant showing a reduction in THI score of >7 points from baseline (the Minimal Clinically Important Difference). Reported as the percentage of participants in each group who meet this criterion.

Resting-state EEG data will be recorded and analyzed across the broad frequency spectrum (0.5-100 Hz). The outcome measures include: 1) Power Spectral Density (PSD) across global and local regions; 2) Functional connectivity metrics (e.g., Coherence, Phase Lag Index); and 3) Neural network synchronization. Analysis will be performed to assess changes in cortical activity and inhibition/excitation balance.

Assessed using resting-state fMRI. Metrics include: 1) Amplitude of Low-Frequency Fluctuations (ALFF) and Regional Homogeneity (ReHo) to reflect local spontaneous brain activity; and 2) Functional Connectivity (FC) strength (z-transformed correlation coefficients) within auditory and non-auditory networks (e.g., Limbic system, Salience network, Default Mode Network).

Structural MRI data (T1-weighted images) will be analyzed using Voxel-Based Morphometry (VBM) and surface-based methods. Key metrics include changes in regional Gray Matter Volume (GMV) and Cortical Thickness in tinnitus-related regions (e.g., auditory cortex, prefrontal cortex, hippocampus).

Diffusion Tensor Imaging (DTI) will be used to assess white matter integrity and glymphatic function. Metrics include: 1) Fractional Anisotropy (FA) and Mean Diffusivity (MD) of auditory pathways; and 2) The DTI-ALPS (Analysis along the Perivascular Space) index, used as a proxy for measuring glymphatic system activity and waste clearance efficiency.