Experimental device tested to help treat ringing in the ears

For people with tinnitus, the persistent sense of ringing in the ears is mildly annoying at best and disabling at worst.

But a new device may help ease the phantom noises, researchers report.

The experimental device uses precisely timed sound and skin stimulation to target nerve activity in the brain. It quelled the bothersome sounds in lab animals and improved quality of life in a test group of 20 humans, according to University of Michigan researchers. 

"Animal studies have identified specific nerve cells in the brain, called fusiform cells, that signal phantom sounds to the rest of the brain," said lead researcher Susan Shore. 

In someone with tinnitus, fusiform cells increase activity as they normally would in the presence of a real sound, she explained. "These signals are transmitted to the auditory part of the brain and are interpreted as sound when there is no sound stimulus," said Shore, a professor of otolaryngology, physiology and biomedical engineering. 

Some 15 percent of Americans suffer from tinnitus. About 2 million can't work or carry out other daily activities because of the constant ringing or grinding in their ears or the resulting stress it causes, the researchers said in background notes. The problem often stems from exposure to loud noise, or head and neck trauma.

The new study shows fusiform cell activity can be tamed using a combination of sounds and mild electrical stimulation of the skin. 

The home device tested in the study supplies the stimulation through electrodes and earphones, Shore said. 

Patients used the device 30 minutes a day for four weeks. After one week, the volume of the tinnitus returned, but the improvement in quality of life lasted up to several weeks, she noted. 

Patients who used a phony device had no improvement in their tinnitus, Shore said. 

A larger trial will try the treatment for longer. "We don't know at this point whether they will need to continue to use it every day, or if they will just need to do it once a week or so. This will have to be determined," she added.

The cost of the device isn't yet known because the treatment is still in development, Shore pointed out.

There is no cure for tinnitus. But some people get emotional relief through cognitive behavioral therapy or sound therapy, according to the American Tinnitus Association. 

In severe cases, some patients try invasive treatments, such as deep brain stimulation and vagal nerve stimulation, Shore said.

The new, non-invasive device relies on so-called stimulus timing-dependent plasticity, or STDP. It aims to correct the nerve malfunction at the root of tinnitus by directing sound into the ears and alternating mild electrical pulses to the cheek or neck. 

For the study, Shore and colleagues sought out tinnitus patients who could temporarily change their symptoms by clenching their jaws, sticking out their tongues, or turning or flexing their necks. These patients appear to benefit most from the combination of audio and electrical stimuli, the study authors noted.

To determine the best timing of the impulses, Shore's team tested the device on guinea pigs that had noise-induced tinnitus.

In the human trial, half the patients received treatment for four weeks, while the other patients received sounds without electrical stimulation.

After a one-month break, the study resumed, but patients switched to the other treatment. 

People who received STDP reported improvement in their symptoms and better quality of life. Some said the phantom sounds got less harsh or piercing or became easier to ignore. 

Dr. Harrison Lin is an assistant professor in the department of otolaryngology-head and neck surgery at the University of California, Irvine Medical Center.

He said this new technique might be a breakthrough for some tinnitus patients.

"This report of a non-invasive, well-tolerated method of reducing the volume of tinnitus for people suffering from bothersome and intolerable tinnitus is incredibly important," said Lin, who wasn't involved in the study.

"This approach will hopefully mature into new, safe and effective treatment options, which are currently sorely lacking," he added.

The report was published Jan. 3 in the journal Science Translational Medicine.