New Device Developed for Somasensory Tinnitus

ANN ARBOR, MICHIGAN — Researchers at the University of Michigan’s Kresge Hearing Research Institute recently developed a device for individuals suffering from annoying or debilitating tinnitus. Led by Susan Shore, PhD, the experimental intervention combines auditory and mild electrical pulse stimulation that offers promise as a neurologic approach to treating the incapacitating effects of tinnitus.

The device, developed by the team at the University of Michigan, uses targeted bimodal auditory-somatosensory stimulation, in which sounds that are emitted into the ear through inserted earphones are alternated with precisely timed weak electrical pulses to the cheek or neck. The approach is designed to “reset” the activity of fusiform cells, which, located in the dorsal cochlear nucleus region of the brainstem, normally help the brain tune out sensations related to the movement of the head and neck. Fusiform cells have been found in other studies to be altered in some people with tinnitus.

Exploring Tinnitus Treatment

The study used bimodal auditory-somatosensory stimulation to alleviate tinnitus in humans, and was published January 3 in Science Translational Medicine.

Twenty participants with tinnitus were randomly assigned in a crossover design to receive either 4 weeks of daily 30-minute sessions using the take-home device, which was calibrated to the loudness and pitch of the phantom sounds in the patients’ unique tinnitus symptoms, or a bogus treatment involving only sounds and no stimulation.

After the 4 weeks and a 4-week washout break, each group was switched to the alternative treatment regimen. Overall, the active treatment was associated with significant decreases in the loudness of phantom sounds (P < .05), assessed according to cumulative measures on TinnTester software of how loud patients’ tinnitus sounds were, whereas no improvements were associated with the sham treatment.

The loudness reduction reached an average of about 12 dB in the fourth week of treatment in the active treatment group, with patients reporting that their tinnitus was less “harsh” or “piercing” and more “mellow,” and two patients reported complete elimination of their tinnitus by the end of the period.

The intrusiveness of tinnitus and quality of life also improved with the active treatment, with mean overall scores on the Tinnitus Functional Index (TFI) decreasing from baseline of 29.2 units to 22.9, with a lower score representing less impact from tinnitus. Ten of the 20 participants had TFI reductions of at least 13 points during treatment, considered clinically meaningful.

An important part of the study criteria required that patients display a somatosensory component of their tinnitus symptoms, which is reported in upwards of 75% of patients with tinnitus. A somatosensory component to tinnitus is associated movements such as jaw clenching, sticking out their tongues, or turning or flexing their necks. Such symptoms suggest the potential for an external somatosensory signal to alter the activity of fusiform cells.

Larger Tinnitus Clinical Trial Planned

The researchers are moving ahead with a larger clinical trial with funding from the National Institutes of Health. The study will have a planned enrollment of 50 participants and will extend the treatment from 4 to 6 weeks.

Should the findings in humans be replicated this device could represent a convenient in-home tinnitus treatment. The University of Michigan has a patent on the concept and is pursuing its potential commercialization.

Source: U of M; Tinnitus Treatment Tackles Underlying Mechanisms, Nancy A. Melville, January 15, 2018, Medscape News