Transcranial magnetic stimulation

Of all the potential treatments for tinnitus, repetitive transcranial magnetic stimulation (rTMS) seems to be the one attracting most attention from researchers. In the final quarter of 2015 six such studies were published. However, only three of these studies offer us good evidence as to the effectiveness of rTMS.

rTMS research is complicated by the fact that there are different versions of rTMS; the type of magnetic-field generator (‘coil’), the number of impulses given, and the part of the brain stimulated can all vary. Different ways of measuring treatment outcomes are also in use. In a small randomised control trial (RCT) [1] US researchers used magnetic resonance imaging (MRI) to measure changes in neural connectivity in regions of the brain considered relevant in tinnitus. The rTMS was focussed on one of the brain’s auditory areas, known as the ‘temporoparietal junction’ (TPJ). Participants received rTMS or a sham treatment for five sessions per week for two weeks in some cases and four weeks in others. Disappointingly, there were no significant differences in the connectivity measurements after treatment in either treatment or control patients.

A German team [2] compared what they describe as ‘conventional’ rTMS (applied to the TPJ) with a new approach in which a double-cone coil was applied to both the TPJ and another area of the brain, the medial frontal cortex. Participants were randomly assigned to one treatment or the other (given over 10 consecutive days). In each group a minority of the patients were considered to have responded to the treatment, defined as a five-point improvement (or more) on a score using a standard tinnitus questionnaire (TQ). There was no significant difference between the groups in the number who responded. There were no serious adverse effects, though some patients complained of headaches and seven decided not to complete the study.

In another small controlled study [3], this time from China, the main focus was rTMS for patients diagnosed with a type of sudden deafness, also known as sudden sensorineural hearing loss (SSHL). Many people with SSHL also develop tinnitus, including 32 of the 54 patients in this study. The severity of their tinnitus was scored on the basis of the patients’ answers to two standard TQs. A significant improvement in tinnitus was found in the treatment group, whereas there was none in the control patients. The treatment group also showed improvements in their hearing.

So does rTMS actually work? Despite all the information now available, this is still not clear. What is certain is that it’s time for a rigorous review of all the evidence, leading on to a single, large multi-centre trial conducted to the highest standards.

Cochlear implants

A technique attracting considerable attention as a treatment for hearing loss is cochlear implantation. Could it also help people with tinnitus? We are starting to see some small studies attempting to answer this question.

A Belgian study [4] involved interviews and the use of standard TQs with 23 people who had received cochlear implants, to treat hearing loss in one ear 3–10 years previously. All patients still had their implants in place, switched them on first thing every morning, and used them throughout the day; 70% said their tinnitus level decreased within one minute of switching on. Scores from the questionnaires showed improvement in tinnitus typically began three months after implantation and then remained stable. Hyperacusis was also reduced for some patients. This is not a rigorous experimental study but the results are encouraging – for people with tinnitus who also have hearing loss – particularly as they concern long-term use of this treatment.

Another paper [5] reports a series of cases, in the USA, in which 10 patients who already had cochlear implants were asked to select background sounds they thought might help their tinnitus. Their chosen backgrounds were then played to them from a portable sound player, so they heard both the background and the sounds amplified by the implant. The effects varied considerably between patients and the researchers analysed each patient’s response separately using several techniques. Nevertheless, they felt able to conclude that, for some patients with cochlear implants, ‘a background sound mixed with the microphone input can be effective for suppressing tinnitus during daily use’.

Also in the USA, another type of implant called a percutaneous osseointegrated auditory implant has been investigated [6]. These implants are inserted through the skin and integrated into bone tissue. Ten patients, all with hearing loss in one ear, were given implants and asked to complete standard TQs before treatment and six and twelve months later. Most patients showed an improvement in their tinnitus, particularly those with the most profound hearing loss. Further research with the implants would be worthwhile.

Other devices

Researchers in Iran [7] employed electrical (rather than magnetic) stimulation of neurons in the brain, a technique known as transcranial direct current stimulation (tDCS). This small RCT involved five sessions of tDCS or a sham treatment on consecutive days. Scores from standard TQs, before and two weeks after treatment, showed no difference between treatment and control groups. A few patients (in both groups) said their tinnitus had worsened.

Meanwhile, also from Iran [8] an RCT has been reported, involving 66 patients, in which laser therapy was used to treat tinnitus. On three different scales, researchers found no difference between treatment and control groups.

Psychology

A systematic review [9] has been published of studies of cognitive behavioural therapy for tinnitus delivered over the internet (iCBT). The reviewer, in the US, found nine controlled studies, some of which was his own group’s research. In some studies iCBT was compared to face-to-face group CBT; in other studies there were control groups receiving no therapy. In total the studies involved over 500 patients. From their detailed analysis of all the data, the reviewers conclude the technique ‘holds promise’ but that further research is still needed.

Pills and potions

Antioxidants have been proposed as therapy for all manner of conditions. In an RCT in Brazil [10] researchers used antioxidants as a treatment for tinnitus in 58 people, all aged over 60. The patients were divided into four groups, three received different substances known to have anti-oxidant properties; the fourth received a placebo. After six months there was no significant change in Tinnitus Handicap Inventory (THI) score in any group.

One well-known antioxidant is ginseng. Tinnitus researchers in Korea [11] randomly divided 61 patients into three groups – two received different doses of red ginseng and one a placebo. After four weeks THI score had risen significantly in the group reiving the higher dose rate but not in the other groups. Improved emotional and mental health scores were also recorded. But, while the patients were randomly assigned to the different groups, no attempt was made to ‘blind’ them to which treatment they were receiving. Such ‘open-label’ research does not generate reliable evidence because of the strength of the placebo effect.

Complementary therapies

Finally, a journal of alternative medicine has published a discussion article [12], not to be confused with a systematic review, looking at research on several forms of tinnitus treatment, including education, counselling, meditation, acupuncture and other complementary therapies. They argue that there is ‘emerging evidence’ to support the use of alternative medicine by people with tinnitus, calling for an ‘integrated’ approach involving both orthodox and complementary medicine.

References

1. Roland LT, Peelle JE, Kallogjeri D et al. The effect of noninvasive brain stimulation on neural connectivity in Tinnitus: A randomized trial.Laryngoscope 2015;30 Sep.

2. Kreuzer PM, Lehner A, Schlee W et al. Combined rTMS treatment targeting the anterior cingulate and the temporal cortex for the treatment of chronic tinnitus. Sci Rep 2015;15 Dec.

3. Zhang D, Ma Y. Repetitive transcranial magnetic stimulation improves both hearing function and tinnitus perception in sudden sensorineural hearing loss patients. Sci Rep 2015; 14 Oct.

4. Mertens G, De Bodt M, Van de Heyning P. Cochlear implantation as a long-term treatment for ipsilateral incapacitating tinnitus in subjects with unilateral hearing loss up to 10 years. Hear Res 2016;331:1-

5. Tyler RS, Keiner AJ, Walker K et al. A series of case studies of tinnitus suppression with mixed background stimuli in a cochlear implant. Am J Audiol 2015;24:398-410.

6. Indeyeva YA, Diaz A, Imbrey T et al. Tinnitus management with percutaneous osseointegrated auditory implants for unilateral sensorineural hearing loss. Am J Audiol 2015; 24:398-410.

7. Forogh B, Mirshaki Z, Raissi GR et al. Repeated sessions of transcranial direct current stimulation for treatment of chronic subjective tinnitus: a pilot randomized controlled trial. Neurol Sci 2015;24 Oct.

8. Dehkordi MA1, Einolghozati S, Ghasemi SM et al. Effect of low-level laser therapy in the treatment of cochlear tinnitus: a double-blind, placebo-controlled study. Ear Nose Throat J 2015;94:32-36.

9. Andersson G. Clinician-supported internet-delivered psychological treatment of tinnitus. Am J Audiol 2015;24:299-301.

10. Polanski JF, Soares AD, de Mendonça Cruz OL. Antioxidant therapy in the elderly with tinnitus. Braz J Otorhinolaryngol 2015;17 Oct.

11. Kim TS, Lee HS, Chung JW. The Effect of Korean red ginseng on symptoms and quality of life in chronic tinnitus: a randomized, open-label pilot study. Audiol Otol 2015;19:85-90.

12. Wolever RQ, Price R, Hazelton AG. Complementary therapies for significant dysfunction from tinnitus: treatment review and potential for integrative medicine. Evid Based Complement Alternat Med 2015; 20 Sep.

Image: cochlear implant device being worn