The results of a small clinical trial to test the safety of a new treatment for tinnitus, or ringing in the ears, showed positive results according to a study newly published online in the journal Neuromodulation: Technology at the Neural Interface.
Led by the University of Texas at Dallas, the trial showed that vagus nerve stimulation-tone therapy is safe for the treatment of tinnitus and brought significant improvement to some participants.
The new treatment combines vagus nerve stimulation (VNS) with auditory tones to alleviate the symptoms of chronic tinnitus.
Electrical stimulation of the vagus nerve
The electrical stimulation is delivered using an electrical pulse generator which is connected to the vagus nerve inside the neck via implanted electrodes.
One of the trial investigators, Dr. Sven Vanneste of the School of Behavioral and Brain Sciences at UT Dallas, says the main goal of the trial was to evaluate the safety of VNS-tone therapy in tinnitus patients, and they found it was safe, with no adverse events.
He says tinnitus affects more than 12 million Americans severely enough to seek medical help. Two million sufferers are so disabled by the ringing in the ears that they can't function normally. And unfortunately, there is no consistently effective treatment.
Safety results 'not surprising'
As far as safety was concerned, the results of the trial were not surprising, explains Dr. Vanneste, because:
"VNS-tone therapy was expected to be safe because it requires less than 1 percent of the VNS approved by the FDA for the treatment of intractable epilepsy and depression."
For the study, which was carried out at the University Hospital Antwerp, Belgium, ten patients with tinnitus were implanted with a stimulation electrode directly on the vagus nerve in the neck.
Then every day for 20 days they attended the clinic to receive 2.5 hours of VNS treatment delivered by a pulse generator linked up to the implanted electrode. The treatment was accompanied by sounds that excluded tones matched to those arising from the tinnitus.
The patients had been suffering from tinnitus for at least a year before taking part in the trial, and had experienced no benefit from other therapies, including audiological, drug or neuromodulation treatments.
Half the patients experienced large reductions in tinnitus symptoms
The results showed that half of the patients experienced large reductions in their tinnitus symptoms:
- Three patients showed a 44% reduction in the impact of the illness on daily living.
- Four patients experienced clinically significant reductions in perceived loudness of the tinnitus of 26 decibels.
However, five patients, all of whom were on medication for other conditions, did not experience significant changes. The four who did experience significant improvement were not using any medications.
The investigators suggest drug interactions may interfere with the effects of the VNS-tone treatment.
Dr. Vanneste says:
"In all, four of the ten patients showed relevant decreases on tinnitus questionnaires and audiological measures. The observation that these improvements were stable for more than 2 months after the end of the 1-month therapy is encouraging."
Next steps: larger trial and implantable pulse generators
A larger trial across four different treatment centers is to start soon in the US.
The team suggests while their small trial used electrical stimulation supplied by an external pulse generator, with more research it should be possible to use implanted generators, so patients do not have to attend the clinic to receive the VNS-tone treatment.
In 2012 in The Lancet, Dutch researchers described another promising treatment for tinnitus. They showed that cognitive behavior therapy in addition to sound-based therapy was considerably more effective at reducing symptoms of tinnitus than existing treatments.