Acoustic therapies

Researchers in Brazil based their work on the theory that tinnitus is often caused when hearing loss leads to a reduction in auditory input to the brain, which in turn causes certain neurons to become more sensitive. It is this raised sensitivity, so the theory goes, that can generate tinnitus. Increasing the auditory input, through the use of a hearing aid, could therefore decrease tinnitus level. These researchers provided 24 people aged 60–70 with hearing loss, 12 of whom had tinnitus, with hearing aids. There were no control patients. After three months of what the researchers describe as continuous and ‘effective’ use, tests and questionnaires indicated that those with tinnitus had significantly lower levels of tinnitus perception and nuisance.

Another team in Brazil fitted ten tinnitus patients, not with hearing aids, but with a sound generator in each ear. There were no controls. They used their generators daily for at least six hours over 18 months. Responses varied but nine showed some improvement, as measured on standard scales. The best response to treatment occurred in those with ‘whistle-type’ tinnitus.

‘Notched’ music therapy features in two new research studies. This technique involves playing sounds that have been modified to remove sound energy in the frequency range surrounding that of the tone (pitch) of the individual patient’s tinnitus. This is a tailor-made approach; the pitch of the patient’s tinnitus is identified and they choose music or other pleasant sounds, from which a ‘notch’ of frequency is then removed. Such devices are already on the market. German researchers fitted ten patients with hearing aids that also delivered notched environmental sounds. They call their combined approach notched environmental sound technology (NEST). Ten control patients received hearing aids only. The NEST group showed more improvement, on one standard tinnitus scale, though the difference between the two groups was not statistically significant.

Korean researchers combined notched music with electrical stimulation of the vagus nerve. Thirty patients received this combined therapy and significant improvements on tinnitus scales were reported after ten 30-minute sessions. There was, however, no control group and it is perhaps unlikely that such short exposure to notched music could have played much part in the apparent benefits achieved.

Neuromonics is a tinnitus treatment defined as “a structured programme of audiological counselling and clinical support alongside the fitting of an acoustic stimulation device … customised to individuals’ hearing thresholds.” Again, there are devices already available that deliver this therapy and it has been the subject of several trials. An uncontrolled study conducted in Australia focused on the use of complex measures of brain activity (such as magnetoencephalography), in 10 people without tinnitus and 12 with the condition (before and after 30 weeks of neuromonic treatment). Changes in brain activity after treatment were noted and there were improvements on tinnitus scales.

Virtual reality (VR) therapy combines sound with visual effects; patients are given a head-mounted display coupled with a camera sensor system and immersed in virtual scenes, in which they can ‘move’ by clicking a mouse. It has been used in the treatment of anxiety disorders. French researchers have recently evaluated VR use for tinnitus in a randomised clinical trial (RCT) in which 61 patients were given eight weekly one-hour VR sessions. They were compared with a group of patients given cognitive behavioural therapy (CBT). There was also a small control group of patients who were ‘waitlisted’ to receive treatment in the future. Both treatment groups performed significantly better, on standard tinnitus scales, than did the control group. There was no difference between the VR and CBT groups.

Other approaches

CBT delivered via the internet (iCBT) has attracted a lot of attention, and has been discussed previously in this column, but so far this year just one new study , an RCT, has been reported. Sixty-two patients were given iCBT; the same number were entered in an online discussion group and acted as a control group. The improvement on standard tinnitus scales was considered ‘substantial’ for the iCBT group, which performed significantly better than the control group. Further iCBT studies are in the pipeline.

Acupuncture research is still mostly conducted in China and often reported in journals with no full English translations. However, a systematic review, conducted by Chinese researchers, has attempted to bring together all the data available from RCTs in which acupuncture was used for tinnitus. They found a total of 18 trials, half of them done in China and half elsewhere. Nearly all the Chinese studies reported positive results, while most studies from other countries had negative findings. Overall, the reviewers felt themselves unable to conclude whether acupuncture is or is not effective against tinnitus. However, one new RCT conducted outside China (in Brazil) has just been reported and did find a higher reduction in tinnitus levels in the treatment group, compared with controls.

As previously featured in this column, attempts to stimulate areas of the brain, using either electrical or magnetic devices, have attracted the attention of several research groups. Two further studies of this type have already been published this year, including one RCT, as have a number of articles discussing the evidence now available. We will not devote more space to the topic here, though doubtless we will return to it sometime in the future.

Quality of research

However, is important not just to get more research done but to ensure it is of good quality. It is also desirable to be able to compare the findings of separate studies and to pool the data, to help determine whether results are due to chance or are statistically significant. It is good therefore to see that a US team has conducted a systematic review examining aspects of study quality in tinnitus RCTs. They found a total of 147 trials. In over half the trials, researchers failed to define specifically how they define ‘tinnitus’. Thus it is not clear whether separate studies are considering the same sort of patients. Only 20% of the trials had a low risk of bias, as defined by the scoring system used by the reviewers. Quality issues of particular concern include the high proportion of patients ‘lost to follow up’ in many trials. Many study reports failed to state whether there were or were not any adverse responses to treatment. As most people in tinnitus trials have been older patients, it is not clear whether their findings are applicable to younger people with the condition. Arguably, this review is the most important piece of tinnitus research published so far this year, as it should inform the design and quality of future studies.