Can High Strength Magnetic Fields be used to treat tinnitus?

Transcranial Magnetic Stimulation: a possible treatment for some tinnitus sufferers?

A number of researchers around the world have been investigating whether a new technique known as Transcranial Magnetic Stimulation, or TMS can be used in treating tinnitus.� TMS was developed in the mid 1990's and the basis of it involves placing a powerful electromagnet against the head. When activated the magnetic fields can be strong enough to change activity in brain areas close enough to the magnet.� This depends on the characteristics of the current, such as frequency and strength, and the specific nature of the nerve cells in the area treated.

A number of small trials have already been carried out in Europe and others are planned to be carried out in the US.�

Effect of TMS is dependent on magnetic field strength
In Belgium, TMS was used in 114 patients with a unilateral or one-sided tinnitus. This study used a relatively lower strength of magnetic field to produce a short-lived decrease in tinnitus. Of these patients 25% that the brief decrease in their tinnitus was marked, with a further 28% describing a more moderate reduction.� They also found that different types of stimulus were necessary for reducing the tinnitus depending on how long the patient had been suffering from tinnitus. It was found more difficult to suppress the tinnitus in those who had it longest.

In Germany, a smaller study in fourteen patients used magnetic fields with higher strength. Importantly, this was a double blind study, where neither patients nor researchers knew if the device was active until after the study was finished. These patients also had specialised brain scans using MRI scans that suggested their tinnitus was associated with increased activity in the same region of the brain dealing with sound processing (the auditory cortex).

For one week, half the patients were given the high strength magnetic stimulation over this brain region for about twenty minutes per day.� The other half had the magnet placed on the head but did not receive any stimulation, which was considered as the� 'placebo' treatment. Those receiving the high strength TMS said there was significant improvement in their tinnitus but the placebo subjects didn't experience this.

Effects of TMS may be medium to long term for some patients
The two groups were then switched over for so that the 'placebo' group patients also received the active TMS treatment. Promisingly, the overall results were that 11 out of 14 patients experienced tinnitus reduction with the higher strength treatments and even after six months 8 out of 14 patient were still reporting tinnitus reduction.

Additional reports of effectiveness, including within the UK, appear to support the findings of these published studies. Whilst these results from these small short-term trials show promise, more detailed research needs to be carried out to answer some fundamental questions about. These include: Can these early results be consistently repeated by other researchers?�What are the optimal therapeutic regimes to use? What is the best strength of magnetic field to employ and in what type of tinnitus patient?� How safe is TMS in the longer term and does it have any effect on other brain activity?� With continued research efforts, answers to these key questions should begin to be provided within the next three to five years.��

References

De Ridder et al. (2005). Transcranial magnetic stimulation for tinnitus: influence of tinnitus duration on stimulation parameter choice and maximal tinnitus suppression. Otology & Neurotology, 26, 616-9.

Kleinjung et al. (2005). Long-term effects of repetitive transcranial magnetic stimulation (rTMS) in patients with chronic tinnitus. Otolaryngology-Head and Neck Surgery, 132, 566-9