Facial movement and pupil dilation reveal severity of tinnitus

Scientists identify objective biomarkers of tinnitus severity through subtle facial movements and students’ responses to sounds, and have the potential to alter the way this wide range of hearing impairments is evaluated and treated. Breakthrough research published in the release of April 30 Scientific Translation Medicinethe major obstacles to the development of tinnitus therapy can be overcome by providing quantifiable measurement methods for conditions previously assessed only by subjective questionnaires.

Tinnitus – the sound sounds like it’s ringing, buzzing or clicking – affects about 12% of adults and is often accompanied by a hypersensitivity reaction to everyday sounds. Although many learn to live with it, an estimated 15% of patients experience debilitating effects that disrupt sleep, mental health, and daily functions.

Measuring Unmeasurable: A New Way

“Imagine if the severity of cancer is determined by providing a questionnaire to patients, this is a condition where some common neurological diseases (such as tinnitus),” said Dr. Daniel Polley, vice chairman of Basic Science Research and deputy director of Eaton-Pascoe Laboratory. “This is the first time we have directly observed a signature of tinnitus.”

The team studied 97 adults with normal hearing – 47 years old who had different tinnitus and sound sensitivity, without these conditions. The researchers not only focused on standard hearing measures, but also investigated the sympathetic nervous system’s response to sound stimulation, ranging from pleasant to painful.

Unexpected revelations in facial movements

Using AI-driven video analysis, the researchers detected subtle, involuntary facial movements closely related to reported levels of distress in tinnitus. The findings even surprised researchers, who were initially unsure that their method would produce results.

“When we started this study, we didn’t know if sounds caused facial movements; therefore, it was surprising to find that these movements not only occur but also provide the most useful measures of tinnitus to date,” Poly noted.

The study identified different autonomous signatures between participants in the discipline of tinnitus and control:

• People with severe tinnitus show exaggerated student swelling to all sounds regardless of emotional content
• The same individuals exhibit facial response blunting to sounds that usually cause strong reactions
• Control participants and those with mild tinnitus showed a greater proportion of responses – a few students’ dilation and facial movements were only for the most unpleasant voices
• These objective measures accurately predicted the individual tinnitus severity score from the standard questionnaire

Beyond the traditional central income theory

This study challenges existing models that focus primarily on tinnitus with interrupted auditory processing. Although the researchers confirmed that participants in tinnitus showed enhanced amplitude of neural responses to sounds (called central gain), this measurement alone did not predict the severity of their condition.

Instead, studies have shown that auditory connections—brain paths that link sound processing to emotional responses—maybe better explain why some people are in trouble, while others adapt to similar phantom sounds. This disorder is manifested by autonomous signatures visible in facial movements and student responses.

Applications of clinical evaluation and therapeutic development

What is particularly promising about these findings is their accessibility. Unlike expensive brain imaging techniques, the approach uses relatively common techniques that have the potential to adapt to the clinical environment.

“What is really exciting is that this is a vantage point for the severity of tinnitus that does not require a highly specialized brain scanner; instead, this approach is relatively low,” Poly said. “If we can adapt this approach to consumer-grade electronics, they can be used in hearing health clinics as an objective measure of clinical trials and fully utilized by the public.”

The ability to objectively measure the severity of tinnitus can alter the clinical trials of potential treatments hindered by the lack of quantifiable results outside of subjective patient reports.

Future research directions

While promising, the study has limitations. To establish clean measurements of video-based methods, the researchers ruled out many people with concurrent conditions with severe tinnitus, such as hearing loss, advanced age or mental health challenges.

The research team has developed new treatments by using these biomarkers, combining neural stimulation with an immersive software environment designed to alleviate tinnitus symptoms to develop new treatments to extend their findings.

“These biomarkers have become the source of trouble,” Poly explained. “While imaging may show hyperactivity brain regions in patients with tinnitus, these biomarkers reveal threat assessment systems across the body that operate outside their normal range, resulting in painful symptoms they experience.”

The study could ultimately provide relief to millions of people with previously difficult conditions to quantify and treat, and offer hope when treatment options are limited.