Tinnitus suppression by electrical promontory stimulation (EPS) in patients with sensorineural hearing loss

Almost 10-15% of the population suffer from chronic tinnitus. There are clinical indications that a 'pathological sound' may be induced by any level of the auditory pathways. Theraupeutical difficulties and many hypotheses about tinnitus and places from which they originate might indicate various methods of treatment. Electrostimulation tinnitus suppression was achieved by many authors from 22 (Graham, Hazell) to 87% (Portman). The aim of our study was to define the usefulness of electrostimulation in treatment of persistent noise induced cochlear lesion tinnitus (group I - 43 men) and compare the results with the non noise induced tinnitus group II (68 patients).

Otolaryngological and audiological examination of the patients was made before and after electrostimulation, and at 90 days. The stimulation system consisted of a prototype tinnitus suppressor, the active platino-iridium needle electrode and silver surface electrode located on the forehead. Transtympanal electrical stimulation was performed using positive polarity direct current. Parameters of electrical impulse were individually different and depended on tinnitus parameters and patients sensation. The current levels ranged from 20 to 600 microA and frequency ranged from 60 to 10000 Hz. Average time of EPS was 60 s.

The control examination 90 days after stimulation in group I showed subjective improvement in 18 (41.9%) patients, 22 (51.2%) did not notice any change and tinnitus deteriorated in 3 (6.9%) of the patients. In the comparative group II improvement was occurred in 34 (50%) persons including 2 (17.6%) in whom tinnitus was abolished, in 30 (44.1%) tinnitus was unchanged and 4 (0.6%) became worse. In both groups our method did not have a destructive influence on hearing. Electrical stimulation to relieve tinnitus has been used for nearly 200 years, but it is unclear how electrical stimulation works to suppress tinnitus.

In our opinion electrical stimulation by using positive DC changes the spontaneous activity of cochlear nerve fibres. According to our results it is suggested that the mechanism of beneficial effects is due to increased microcirculation in part of the auditory pathways. Poorer results in patients with noise induced tinnitus could be explained by greater damage of the cochlea outer hair cells. In our opinion EPS could be a method of treatment for persistent tinnitus in cases which fail to respond to other methods.