Targeted nerve stimulation could yield a long-term reversal of tinnitus, a debilitating hearing impairment affecting at least 10 percent of senior citizens and up to 40 percent of military veterans, according to an article posted in the Jan. 12 online edition of Nature.
Researchers Dr. Michael Kilgard and Dr. Navzer Engineer from The University of Texas at Dallas and University-affiliated biotechnology firm MicroTransponder report that stimulation of the vagus nerve paired with sounds eliminated tinnitus in rats. A clinical trial in humans is due to begin in the next few months.
Described as a ringing in the ears, tinnitus causes mild irritation for some people but is disabling and painful for many others. The U.S. Veterans Administration spends about $1 billion a year on disability payments for tinnitus, said Kilgard, associate professor in the School of Behavioral and Brain Sciences at UT Dallas and co-author of the journal article.
"Brain changes in response to nerve damage or cochlear trauma cause irregular neural activity believed to be responsible for many types of chronic pain and tinnitus," he said. "But when we paired tones with brief pulses of vagus nerve stimulation, we eliminated the physiological and behavioral symptoms of tinnitus in noise-exposed rats."
The researchers are, in essence, retraining the brain to ignore the nerve signals that simulate ringing. They monitored the laboratory rats for several weeks after therapy, and the improvements persisted.
"This minimally invasive method of generating neural plasticity allows us to precisely manipulate brain circuits, which cannot be achieved with drugs," said Dr. Navzer Engineer, vice president of preclinical affairs at MicroTransponder and lead author on the study. "Pairing sounds with VNS provides that precision by rewiring damaged circuits and reversing the abnormal activity that generates the phantom sound."
The research team is dev
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University of Texas at Dallas