STOP THE RINGING: Tinnitus can manifest early in auditory perception, as damage to the inner ear, or in the brain where sounds are processed. Researchers developing treatments for the condition are targeting various points along this pathway.
See full infographic: JPG© MARI SCHMITT/SCIENCE SOURCE; © ENCYCLOPEDIA BRITANNICA/UIG/GETTY IMAGESIt often starts off with a bang. Many a soldier, construction worker, concertgoer, or innocent passerby exposed to a loud noise walks away with the telltale symptom of tinnitus, a persistent ringing in the ears. The condition can also arise from other ear traumas, such as middle-ear infections or exposure to high pressure while scuba diving, and begins with damage to the hair cells in the cochlea of the inner ear or to the auditory nerve. Until recently, such damage was thought to be the cause of the phantom sounds that plague tinnitus sufferers. Now, researchers are realizing that it’s much more complex than that.
“Damage to hair cells and auditory nerve fibers sets the stage for the development of tinnitus,” says Jennifer Melcher of the Massachusetts Eye and Ear Infirmary. But the true culprit is really the brain, which eventually begins to compensate for the loss of input from the ear by “turning up the volume” on the sound signals it is trying to pick up, she adds. Navzer Engineer, chief scientific officer of Dallas-based MicroTransponder, which is developing a neurostimulative treatment for tinnitus, agrees: “Cells in the brain don’t stay dormant” even though they have lost input from the ear, he says.
It’s unclear when the condition transitions from the ear to the brain. Researchers also do not yet know whether the brain or peripheral nerves are primarily ...
