This new machine could finally cure the din of tinnitus with electric shocks to the brain
Tinnitus can be an infuriating condition, with the sufferer hearing buzzing, whistling or any number of other sounds from inside their body. It can be a passing irritation, caused by an ear infection or waxy buildup, but many cases are chronic. Worse still, there’s no single treatment. If you have incurable tinnitus, your current options are counselling, sound therapy and cognitive behavioural therapy to help you live with it.
A new study, published in Science Translational Medicine, presents a more encouraging prospect: offering a way to silence tinnitus by attacking the neurological roots of the condition.
One of the leading theories about what causes tinnitus traces the problem to the brain’s dorsal cochlear nucleus. This is one of two areas in the brainstem where auditory information is processed, and consists of neurons called fusiform cells. If these neurons misfire, become hyperactive and synchronise with each other, they can transmit phantom signals to other areas of the brain – which are perceived as sound.
“If we can stop these signals, we can stop tinnitus,” says Dr Susan Shore, the University of Michigan Medical School professor who led the research team. “That is what our approach attempts to do, and we’re encouraged by these initial parallel results in animals and humans.”
The team at the University of Michigan tested a device (which they’ve also patented) that emits a combination of sound pulses, relayed via headphones, and electrical pulses, delivered to the cheek or neck. These pulses are specifically timed to reset the activity of the brain’s fusiform cells, using a process called stimulus-timing dependent plasticity (STDP). After promising tests on guinea pigs with noise-induced tinnitus, they moved onto a human study, recruiting 20 volunteers to take part in a 16-week experiment.
Two devices were used: one that emitted mild shocks and sounds, and a “sham” one that emitted only sounds. One half of the group used the former daily for four weeks, and the other used the latter. After a four-week break, the groups swapped, using the other device for four weeks, finally followed by a closing four-week break.
While the “sham” treatment didn’t result in any changes, the shock-and-sound devices – tailored to the loudness and pitch of the patients’ phantom sounds – led to an overall decrease in the subjects’ reports of tinnitus. Two even said that their condition disappeared completely, if only for a short time. In a survey, the participants noted reduced stress during the time of the treatment, and a better quality of life.
The results are promising, particularly as the treatment is non-invasive. There are, however, noted limitations. The participants in the study all had a particular form of tinnitus – one that can be assuaged by clenching the jaw or flexing the neck (which may themselves be crude ways to modulate the activity of fusiform neurons). Not all tinnitus sufferers can use this method, however, meaning the treatment may not work for everyone.
“We’re definitely encouraged by these results, but we need to optimise the length of treatments, identify which subgroups of patients may benefit most, and determine if this approach works in patients who have nonsomatic forms of the condition that can’t be modulated by head and neck manoeuvres,” Shore says.
A larger test group for the device is due to begin in late summer this year, so here’s hoping Shore and her team can continue their success in fighting the phantom din of tinnitus.
Image credit: University of Michigan