A study of electrical promontory stimulation in tinnitus patients

Systematic Review on Intra- and Extracochlear Electrical Stimulation for Tinnitus

Several electrical stimulation patterns of the auditory nerve have been described for tinnitus relief, but there is no consensus on the most effective stimulation pattern. Therefore, we aim to systematically review the literature on the effect of intra- and extracochlear electrical stimulation patterns as a treatment option for patients with tinnitus. Only studies on intra- and extracochlear electrical stimulation for patients with tinnitus were included if the stimulation used did not concern standardized CI stimulation patterns to primarily rehabilitate hearing loss as intervention. A total of 34 studies met the inclusion criteria, with 10 studies (89 patients) on intracochlear electrical stimulation and 25 studies on extracochlear electrical stimulation (1109 patients). There was a high to medium risk of bias in 22 studies, especially due to lack of a non-exposed group and poor selection of the exposed group. All included studies showed subjective tinnitus improvement during or after electrical stimulation, using different stimulation patterns. Due to methodological limitations and low reporting quality of the included studies, the potential of intra- and extracochlear stimulation has not been fully explored. To draw conclusions on which stimulation patterns should be optimized for tinnitus relief, a deeper understanding of the mechanisms involved in tinnitus suppression is needed.

Electrical Stimulation of the Ear, Head, Cranial Nerve, or Cortex for the Treatment of Tinnitus: A Scoping Review

Tinnitus is defined as the perception of sound in the absence of an external source. It is often associated with hearing loss and is thought to result from abnormal neural activity at some point or points in the auditory pathway, which is incorrectly interpreted by the brain as an actual sound. Neurostimulation therapies therefore, which interfere on some level with that abnormal activity, are a logical approach to treatment. For tinnitus, where the pathological neuronal activity might be associated with auditory and other areas of the brain, interventions using electromagnetic, electrical, or acoustic stimuli separately, or paired electrical and acoustic stimuli, have been proposed as treatments. Neurostimulation therapies should modulate neural activity to deliver a permanent reduction in tinnitus percept by driving the neuroplastic changes necessary to interrupt abnormal levels of oscillatory cortical activity and restore typical levels of activity. This change in activity should alter or interrupt the tinnitus percept (reduction or extinction) making it less bothersome. Here we review developments in therapies involving electrical stimulation of the ear, head, cranial nerve, or cortex in the treatment of tinnitus which demonstrably, or are hypothesised to, interrupt pathological neuronal activity in the cortex associated with tinnitus.

Feasibility, safety and efficacy of transcutaneous vagus nerve stimulation in chronic tinnitus: an open pilot study

OBJECTIVES

Vagus nerve stimulation represents an established treatment strategy for epilepsy and affective disorders. Recently, positive effects were also shown in animals and humans with tinnitus. Here we report the results of an open pilot study exploring feasibility, safety and efficacy of tVNS in the treatment of chronic tinnitus.

STUDY DESIGN

Fifty patients with chronic tinnitus underwent tVNS in an open single-armed pilot study which was conducted in two phases applying two different stimulating devices (Cerbomed CM02 and NEMOS). Clinical assessment was based on Tinnitus Questionnaire (TQ), Tinnitus Handicap Inventory (THI), Beck Depression Inventory (BDI), WHO Quality of Life, and various numeric rating scales. Primary outcome was defined as change in TQ (baseline vs. final visit in week 24). The study has been registered with clinicaltrials.gov (NCT01176734).

RESULTS

Primary analysis indicated mean TQ reductions of 3.7 points (phase 1) and 2.8 points (phase 2) significant for the first study phase. Secondary analyses indicated a significant BDI reduction for phase 1 (uncorrected for multiple testing), but no further systematic or significant effects. Adverse events included twitching and pressure at electrode placement site. The occurrence of one hospitalization because of palpations and the development of a left bundle branch block were considered as unrelated to the intervention. Cognitive testing revealed no significant changes.

CONCLUSION

Our data demonstrate the feasibility of tVNS over a period of 6 months. There was no clinically relevant improvement of tinnitus complaints. Our data suggest tVNS to be considered safe in patients without a history of cardiac disease.

[Tinnitus treatment by using electrical stimulation]

INTRODUCTION

The aim of the study was to evaluate the influence of electrical stimulation on severe tinnitus.

MATERIAL AND METHODS

The study comprised 46 patients (66 ears) suffering from severe tinnitus, persistently or temporarily, 27 women and 19 men, ranging in age from 22 to 84 years, on average 55. The material was divided into two groups. Group I was treated using electrical stimulation, whereas group II was being applied additionally the kinesitherapy of the cervical part of the vertebral column. The average duration of tinnitus was similar in both groups and equals 4.5 years. All the patients were administered medicines, without expected result. Otolaryngological, audiological diagnostics was conducted as well as head and cervical computer tomography. The patients were asked to fill in the questionnaire concerning tinnitus. The electrical stimulation was performed using silver electrode which was dipped in saline solution in external auditory canal. Direct current was used, the intensity ranged from 0.15 mA to 1.15 mA. Fifteen electrical stimulations were entire treatment administered twice or three times a week. Before and after treatment the subjective evaluation of tinnitus was made.

RESULTS

The subjective improvement was noticed in 36 people (n 46 ears--71%). Persistent tinnitus was registered in 30 ears and temporary in 30 ears, in 6 tinnitus disappeared completely. On the basis of audiometric tests improvement was noticed in 33 ears (55%). In group I in 17 ears (44%)--in 4 ears tinnitus disappeared, in 13 partial relief was noticed, 10 ears were without any change and in 12 ears the intensification of tinnitus was recognized. In group II in 16 ears improvement was observed, in 2 of them tinnitus disappeared, in 14 decreased. In 9 ears no change was obtained and in 2 intensification was noticed.

CONCLUSIONS

Electrical stimulation can be an alternative therapy in severe tinnitus treatment. The administration of kinesitherapy of cervical column may have an additive effect on tinnitus treatment.

Bioengineering Solutions for Hearing Loss and Related Disorders

Advances in digital signal processing, microelectronics, and power technology have produced devices that have contributed significantly to the quality of life and communication abilities of individuals with hearing impairment and tinnitus. Future technological developments will expand the benefits of current devices and offer new treatments for otologic disorders.

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

OBJECTIVE

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).

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Improved word perception in tinnitus patients following electrical stimulation of the ear: a preliminary report

The present study showed that there were close relationships between tinnitus relief and improved word perception by means of a grammatically correct but non-sense Japanese word perception test. Fourteen out of 20 patients reported tinnitus relief and improvement in hearing. Nine out of the 14 patients were thought to be significantly improved in word perception. Improved word perception was observed in 7 out of 10 patients whose ears tested were opposite to ears treated while in 2 out of 10 patients whose ears tested were the same as ears treated. Improved word perception was observed in 5 patients at one segment, 2 patients at two segments and 2 patients at three segments. Improved word perception was observed in one patient at the first segment, 5 patients at the second segment, 5 patients at the third segment and 5 patients at the fourth segment. There were no significant differences in hearing level nor age in patients with and without relief of tinnitus.

Improved word perception following electrical stimulation of the ear in hearing-impaired patients without tinnitus

Improved word perception in hearing-impaired patients following electrical stimulation of ears was shown by means of a grammatically correct but non-sense Japanese 4-segment sentence perception test. Improved word perception was reported in 15 out of 20 patients without tinnitus following electrical stimulation of ears. In 11 out of 15 patients, the number of incorrect words significantly decreased, showing that electrical stimulation of ears improved word perception. Improved word perception was observed in 5 out of 8 patients whose tested ears were contralateral to treated ears while in 8 out of 12 patients whose tested ears were the same as treated ears. The present study suggests that electrical stimulation of ears improves word perception in hearing-impaired patients without tinnitus.

Neural responses to electrical stimulation of the cochlea in guinea pigs

A special bridge circuit was constructed to compensate stimulus artifact to determine the effects of an alternating current (AC) in the range of 3 to 20 kHz and direct current (DC) stimulation on the activity of cochlear nerve fibers. When AC and DC stimulation of the same fiber were compared, a greater current intensity was required to change the spike rate with AC stimulation than DC stimulation. While positive DC stimulation reduced activity, negative DC stimulation increased the spike rate. AC stimuli excited fibers in a manner similar to that observed with negative DC stimulation. Thresholds increased with stimulus frequency, suggesting that the effects of AC stimulation on the discharge rate are independent of the CF (characteristic frequency) of a fiber. The effects of short-time AC and DC stimulation on cochlear fiber activity lasted only during the stimulation, and the spontaneous activity did not significantly differ before and after electrical stimulation.