A constant annoying ringing in the ears – called tinnitus - didn't go away when researchers tried zapping patients' heads with magnetic waves in a recent study.
The researchers still think magnetic therapy could work, if they can find the right part of the brain to apply it to.
"We haven't found the sweet spot yet," said Dr. Jay Piccirillo, the lead author of the study and a professor of ear, nose and throat surgery at Washington University School of Medicine in St Louis, Missouri.
Tinnitus is caused by a "phantom" sound, thought to be the result of mis-wired brain cells.
The condition is common. One study estimated that 50 million Americans experience chronic ringing in their ears at some point in their lives.
Piccirillo said most people are not bothered by the ringing. A very small fraction of people are crippled by the sound, however. Some become depressed, or even suicidal.
Doctors who treated the patients in the current study generated magnetic waves outside each person's head that traveled through the skull into the brain; the waves would temporarily rewire the brain's circuits. Several studies in Europe have found that sessions of such magnetic therapy can help relieve ear ringing.
In the United States, sending magnetic waves to the brain is approved for use in patients with depression, but it is only experimental for tinnitus.
Piccirillo and his colleagues recruited 14 patients who were severely bothered by the ringing in their ears.
All of them received 10 treatments with a magnet over a 2-week period, and another 10 sessions over another 2 weeks using a fake magnet. The order of the 2-week periods was flipped in half of the patients.
After the treatments, the ringing was no better than before.
And when Piccirillo's team asked participants which treatment they thought they received first - the real magnet or the fake magnet - the answers were right only half the time - a result just as good as chance.
Piccirillo told Reuters Health he's not giving up on magnetic therapy. "There's no doubt these magnets work to reorganize brain connections. But we don't know where to put the magnet, and for how long."
In this study, the magnet was placed near the patients' left ear, by the part of the brain that processes sound.
Dr. Robert Folmer, a professor of ear, nose and throat surgery at the Oregon Health and Science University, reviewed the study for Reuters Health.
Folmer, who was not involved in the research, suggested some reasons that could explain why Piccirillo's study didn't work, when previous studies have successfully used magnets to relieve ear ringing.
Two weeks of treatment could be too brief to allow the brain to correct the ringing, he said. And perhaps the left side of the skull is not the correct place to put the magnetic coil in every patient.
"Mostly I was kind of surprised to see how many people were in this study," Folmer said. Fourteen is "a very small number of people."
Piccirillo said his team had planned to include 55 people, but when they realized the treatment wasn't working they decided to stop.
"It's extremely unlikely that you would have seen an effect if we had continued the study," Piccirillo said.
He agreed that the treatment might have been too short. His group is starting a new experiment with 4 weeks of treatments instead of 2 weeks.
Folmer too is soon starting a study of magnetic therapy, in 160 patients with tinnitus. His group will apply the magnet to the left side of the head in some patients, and the right side in others.
The appeal of magnetic therapy is that it is expected to actually reduce the ringing in people's ears.
Currently, the available treatments - such as talk therapy and antidepressant medications - don't get rid of the noise; they only help people cope with it.
Piccirillo's federally-funded study is published in the March issue of the Archives of Otolaryngology-Head and Neck Surgery.