NEW YORK (Reuters Health) - For some people with chronic tinnitus - a persistent, inescapable sensation of ringing in the ears -- repeated magnetic stimulation through the cranium appears to provide temporary relief, Italian researchers report.

However, enthusiasm for repetitive transcranial magnetic stimulation, or rTMS, for tinnitus "should be tempered," Dr. Simone Rossi told Reuters Health. "The beneficial effects of rTMS are short-lived, and only about a half of tinnitus sufferers may benefit from it."

Tinnitus affects millions of people, and in some it can lead to psychiatric distress, sleep disturbances, and work impairment, Dr. Rossi of the University of Sienna and colleagues point out in the Journal of Neurology, Neurosurgery, and Psychiatry.

The team tested the effects of rTMS in 16 patients with tinnitus. They underwent active treatment and sham treatment in random order, without knowing which was which.

During sessions on 5 days, the coil generating the magnetic field was positioned close to the skull over the left temporal region for active treatment; in the sham set up, the coil was positioned at 90 degrees to the head so that the magnetic field pointed away from the brain.

Two patients actually dropped out because of worsening symptoms, the researchers report, but eight patients responded.

Among the responders, subjective tinnitus scores improved by an average of 35 percent, but the condition returned to original levels after 2 weeks.

This good, albeit transient, response, said Rossi "might indicate that the brain reacts somewhat positively to stimulation."

These data "could help in the selection of tinnitus patient candidates for more invasive, chronic, neuromodulatory strategies such as epidural implants on the auditory cortex," Rossi added.

He was referring to what he described as a "sort of pacemaker for brain stimulation." Work on such a device "is in progress in this sense in many labs."