ANTWERP, BELGIUM—Vagal nerve stimulation, which is approved by the Food and Drug Administration (FDA) for treating partial-onset epilepsy and treatment-resistant depression, has shown promise as part of a treatment for alleviating the symptoms of tinnitus.
Writing in the November 20 issue of the online journal Neuromodulation: Technology at the Neural Interface, the researchers report that a study conducted at University Hospital in Antwerp found that 4 of 10 patients, all people with chronic tinnitus, exhibited clinically meaningful improvements in their tinnitus after undergoing vagal nerve stimulation (VNS) over a 20-day period. Five of the six patients who did not show improvement were taking medications that may have interfered with the release of acetylcholine and norepinephrine that is induced by VNS and is essential for inducing plasticity.
The four patients who seemed to be helped by VNS–none of whom were taking other medications–showed improvement in their tinnitus, both for the affective component, as quantified by the Tinnitus Handicap Inventory, and for the sound percept, as quantified by the minimum masking level. They all demonstrated reductions in the perceived loudness of their tinnitus by 26 dB. Three of the four also showed a 44% reduction in the impact of tinnitus on their daily lives. The improvement in symptoms was found to be stable two months after the therapy.
For the study, the tinnitus sufferers were implanted with electrodes on their left vagus nerve. Two and a half hours a day for 20 days, the patients heard tones, excluding the tinnitus-matched frequency, paired with brief electrical stimulation of the vagus nerve. The therapy was well tolerated, and no patient withdrew from the study due to complications or side-effects.
In their conclusion, the scientists stated, “VNS paired with tones excluding the tinnitus-matched frequency is safe and feasible. It seems to exert a beneficial effect in non-medication-taking patients, both with regard to the perceived sound and the distress. Further studies are therefore mandated.”
In an interview with the News Center at the University of Texas at Dallas (U-T Dallas), Michael P. Kilgard, PhD, one of the researchers who authored the report on the study, said, “The primary goal of the study was to evaluate safety of VNS-tone therapy in tinnitus patients. VNS-tone therapy was expected to be safe because it requires less than 1% of the VNS approved by the FDA for the treatment of intractable epilepsy and depression. There were no significant adverse events in our study.”
Kilgard, who is Margaret Fonde Jonsson Professor in the School of Behavioral and Brain Sciences at U-T Dallas, added, “Four of the ten patients showed relevant decreases on tinnitus questionnaires and audiological measures. The observation that these improvements were stable for more than two months after the end of the one-month therapy is encouraging.”
He noted that more than 12 million Americans have tinnitus severe enough to seek medical attention, and 2 million are so disabled that they cannot function normally. He said there has been no consistently effective treatment.
The other authors of the article are Dirk De Ridder, MD, PhD, of the Brain, Tinnitus Research Initiative and the Department of Neurosurgery, University Hospital Antwerp; Sven Vanneste, PhD, Brain, Tinnitus Research Initiative Clinic Antwerp and Department of Translational Neuroscience, University of Antwerp; and Navzer D. Engineer, PhD; MicroTransponder Inc., Austin, TX.