Magnetism can also be used to stimulate electrical activity in the brain. Transcranial magnetic stimulation (TMS), which involves a magnetic coil placed near the head, has received attention from scientists as a possible tinnitus treatment. One recent study carried out in Turkey [3] involved 75 people with tinnitus divided into five groups of 15. In Groups 1 and 2, participants received repetitive TMS (rTMS), given at two different frequencies. Group 3 received the same rTMS as Group 1 plus paroxetine, a drug commonly used as an antidepressant. Group 4 had paroxetine only. Group 5 was a control group receiving sham rTMS.
The researchers used the THI and the Tinnitus Severity Index (TSI), plus other scales, to measure the level of tinnitus before treatment, and one and six months after. The THI and TSI scores improved after treatment in all groups, except the control group. The differences between the four groups receiving active treatment were found to be not statistically significant. A few study participants reported treatment side effects, but these were mild and short-term. The study authors concluded that rTMS and paroxetine, used together or separately, have potential for tinnitus treatment.
The number in each study group is, however, small and further research with more patients (including larger control groups) over a longer period of time is now necessary. There have been previous studies with paroxetine which have not shown it to be effective for tinnitus.
TMS has also recently been studied in an RCT [4] by a team in the USA. They gave 35 people with tinnitus rTMS every day for 10 days, with a further 35 receiving sham treatment. Their primary measure of tinnitus was the Tinnitus Functional Index (TFI), which they used with their participants immediately after treatment and then at intervals over the next six months. Over half of those receiving TMS (56%) were considered to have benefited from the treatment, compared with just 22% of the control group. While the results from this well conducted study are encouraging, the researchers point out that this is a small study and that many questions regarding TFI remain unanswered. They want to see bigger studies that address these questions.
Sadly, we do not have full access to a recent rTMS study conducted by Korean researchers [5] but it appears that working with 14 patients (no control group) they found an improvement in THI using one frequency level but not with another.
Could electrical stimulation, not of the brain itself but of the vagus nerves, offer a way forward? A Finnish team has completed a very preliminary study [6], in which they gave transcutaneous vagus nerve stimulation (tVNS) to seven people with tinnitus and to eight people without the condition. From previous research, they were aware that certain types of electrical activity in the brain (beta-band and gamma-band activity) is usually greater in those who have tinnitus. They confirmed this to be the case in their own study. The administration of tVNS was found by the researchers to 'modulate' (i.e. exert a controlling influence) on beta and gamma-band activity. They did not study the effects of tVNS on tinnitus symptoms but their findings suggest that tVNS does deserve further investigation.
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