Predicting Tinnitus Treatment Response with Brain Biomarkers

A Specific Brain Shape Predicts Who Gets Tinnitus Relief from rTMS

A new study offers a possible explanation for why repetitive transcranial magnetic stimulation (rTMS) helps some tinnitus patients but not others. Researchers found that a specific brain region’s size before treatment strongly predicts whether a patient will respond to rTMS. Patients with a larger volume in the right pars triangularis—a part of the prefrontal cortex involved in complex thinking—were significantly more likely to see their tinnitus improve.

Linking Brain Structure to Treatment Potential

Led by researchers Zhongling Ding, Bo Peng, and Mengfang Gong, the study aimed to find a reliable, pre-treatment marker for rTMS outcome. The team reasoned that since tinnitus involves changes in brain structure and rTMS induces neuroplastic changes, a patient’s starting brain “architecture” might determine their response.

They recruited 64 patients with subjective tinnitus and 18 healthy controls. All patients underwent a two-week course of rTMS. Before treatment began, each participant received a high-resolution structural MRI scan. The researchers then extracted 242 different measurements of brain shape and volume from these scans.

Right Frontal Brain Region Emerges as Key Predictor

After treatment, patients were categorized based on their clinical improvement. Thirty-six patients (56.25%) were classified as responders. By comparing the brain scans of responders and non-responders, the analysis pinpointed 10 specific regional features that differed between the groups.

The most important feature was the gray matter volume of the right pars triangularis of the inferior frontal gyrus (IFGtriang-R). A machine learning model built using these 10 features proved highly effective at predicting who would respond to rTMS. The model, called ExtraTreesGini_BAG_L1, achieved an area-under-curve score of 0.85 and an accuracy of 77%.

A Distinctive Brain Signature

The researchers took the analysis a step further by comparing responders, non-responders, and the healthy control group. They found that the IFGtriang-R volume in responders (0.90 ± 0.08) was significantly larger than in both healthy controls (0.86 ± 0.06) and non-responders (0.86 ± 0.07). This three-way comparison is critical. It shows that successful responders aren’t just at one end of a normal range; they possess a distinct structural trait that differs even from healthy individuals without tinnitus.

This finding suggests that a larger right pars triangularis may represent a form of “neuroplastic reserve.” This could mean the brain has a greater inherent capacity to reorganize and adapt in response to the rTMS pulses, leading to a reduction in tinnitus perception.

Clinical Implications and Future Directions

The study, published with the DOI 10.3389/fneur.2026.1808769, moves the field closer to precision medicine for tinnitus. A simple pre-treatment MRI scan could potentially stratify patients, identifying those most likely to benefit from rTMS. This would save time, cost, and patient disappointment for those unlikely to respond, allowing them to explore alternative neuromodulation approaches or other therapies sooner.

The pars triangularis is part of a broader prefrontal network involved in cognitive control, attention regulation, and auditory stream selection. Its size may influence a person’s ability to cognitively down-regulate the tinnitus signal after rTMS weakens the overactive neural circuits generating the phantom sound. This connects to a broader understanding of integrated auditory health from cochlea to cortex, where higher-order brain regions play a decisive role in the chronic experience of tinnitus.

Future research will need to validate this biomarker in larger, independent patient groups. It also raises questions about whether therapies could be developed to actively enhance this neuroplastic reserve before treatment. The work adds to a growing body of evidence, including past findings on how brain biomarkers predict tinnitus treatment success, highlighting the shift toward personalized neurological care.

For patients considering rTMS, this research underscores that treatment efficacy is not random. It is closely tied to individual neurobiology. As objective predictors like the IFGtriang-R volume are refined, they promise to make tinnitus management more efficient, targeted, and effective.