Electrical Stimulation of the Brain Alleviates Tinnitus

Chronic electrical stimulation of the secondary auditory cerebral cortex could eventually become a potential therapeutic intervention for the suppression of tinnitus.

Researchers at the Medical College of Wisconsin (Milwaukee, USA) conducted a study of cortical stimulation involving eight adult patients with constant tinnitus of at least one year, with a tinnitus reaction questionnaire score greater than 33 (tinnitus was predominantly unilateral with a frequency less than 8,000 Hz). An investigational epidural electrode was surgically implanted over the posterior superior temporal gyrus using functional magnetic resonance imaging targeting. A two-week stimulation period alternated with a two-week sham period in random order to which subjects were blinded. This was followed by continuous stimulation with parameter adjustments to maximize tinnitus suppression. The main outcome measures were subjective rating of tinnitus severity, loudness, and device efficacy, and objective measures of hearing thresholds, tinnitus frequency, loudness, and minimum masking levels.

The results showed there were no effects of stimulation during the four-week blinded period. With continuous chronic stimulation, two patients had persistent reduction of pure-tone tinnitus, and six patients had short periods of total tinnitus suppression. Significant improvements in the Beck Depression Inventory and tinnitus questionnaires were found, although objective measures of tinnitus loudness remained fairly stable. No surgical or stimulation-related complications were noted.

"Whether the effect is durable over the long run remains to be seen,” said lead author neurosurgeon Brian Kopell, M.D. "However, once the kinks are worked out, millions of people could someday benefit from surgery.”

Neurostimulator devices are programmed to deliver an electrical current through an implanted electrode to stimulate targeted nerve cells and nerve fibers in the brain, spinal cord, and peripheral nerves. Targeting neurologic problems at their source can be very effective in regulating or reducing chronic pain and other disorders of the central nervous system.


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