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

Abstract

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.

A multidisciplinary European guideline for tinnitus: diagnostics, assessment, and treatment

“…They can be invasive or non-invasive, and use electromagnetic, electrical, or sound stimuli. However, the precise neural mechanism by which changes occur at both local and network levels is not fully understood [123,158]. Moreover, with non-invasive treatments, the precise area of the brain to be stimulated is unknown.…”

“…That they are invasive means they are not a viable option for widespread use. Research to date is limited to a small number of cases and in each the precise neural mechanism by which changes occur at both local and network levels is not fully understood (for a comprehensive review, see Hoare et al, [123]). There are no RCTs or systematic reviews to date.…”

Neuromodulation for tinnitus treatment: an overview of invasive and non-invasive techniques

“…Different underlying theories assume that a peripheral lesion of the cochlear hair cells induces a suboptimal or maladaptive plasticity of the central nervous system, inducing reorganization and hyperactivity in central auditory and non-auditory structures (Mühlnickel et al, 1998;Kaltenbach and Afman, 2000;Salvi et al, 2000;Eggermont and Roberts, 2004;Vanneste and de Ridder, 2012;Hoare et al, 2016).…”

“…In correlation with electroencephalography (EEG) and magnetoencephalography (MEG) studies, tinnitus is associated with a persistent high-frequency gamma band activity in temporal brain areas (Llinás et al, 1999(Llinás et al, , 2005Weisz et al, 2005Weisz et al, , 2007Vanneste and de Ridder, 2012). Furthermore, theta burst-firing increases the synchronization of neuronal oscillatory activity, which is thought to play a part in the changed neural activity gaining access into consciousness (de Ridder et al, 2015b;Hoare et al, 2016). Alternatively, a noise-cancelling mechanism involving different non-auditory brain areas has been proposed to diminish or prevent tinnitus perception (de Ridder et al, 2014a(de Ridder et al, , 2015b.…”

A Randomized, Placebo-Controlled, Double-Blind, Parallel Groups Study Evaluating the Performance and Safety of a Steady State Coherent Biomodulator Patch in the Treatment of Subjective Tinnitus

“…This is because so much depends on the neuronal activity in the brain and the auditory pathways 23,24 . However, from a broader perspective, it may be important to go from the concept of neuromodulation to the understanding of biomodulation.…”