Abstract
ObjectivesTo compare the event-related potentials (ERPs) and brain topographic maps characteristic and change in normal controls and subjective tinnitus patients before and after repetitive transcranial magnetic stimulation (rTMS) treatment.Methods and ParticipantsThe ERPs and brain topographic maps elicited by target stimulus were compared before and after 1-week treatment with rTMS in 20 subjective tinnitus patients and 16 healthy controls.ResultsBefore rTMS, target stimulus elicited a larger N1 component than the standard stimuli (repeating sounds)in control group but not in tinnitus patients. Instead, the tinnitus group pre-treatment exhibited larger amplitude of N1 in response to standard stimuli than to deviant stimuli. Furthermore tinnitus patients had smaller mismatch negativity (MMN) and late discriminative negativity (LDN)component at Fz compared with the control group. After rTMS treatment, tinnitus patients showed increased N1 response to deviant stimuli and larger MMN and LDN compared with pre-treatment. The topographic maps for the tinnitus group before rTMS -treatment demonstrated global asymmetry between the left and right cerebral hemispheres with more negative activities in left side and more positive activities in right side. In contrast, the brain topographic maps for patients after rTMS-treatment and controls seem roughly symmetrical. The ERP amplitudes and brain topographic maps in post-treatment patient group showed no significant difference with those in controls.ConclusionsThe characterical changes in ERP and brain topographic maps in tinnitus patients maybe related with the electrophysiological mechanism of tinnitus induction and development. It can be used as an objective biomarker for the evaluation of auditory central in subjective tinnitus patients. These findings support the notion that rTMS treatment in tinnitus patients may exert a beneficial effect.
Highlights
Subjective tinnitus is defined as a sensation of noise-like ringing or roaring that is purely subjective phantom phenomenon without any sound source
The majority of patients did not complain of side effects from repetitive transcranial magnetic stimulation (rTMS), apart from a slight transient headache on the stimulation site which did not require pharmacological treatment
We focused on several typical event-related potentials (ERPs) components and compared their differences between normal subjects and patients with tinnitus
Summary
Subjective tinnitus is defined as a sensation of noise-like ringing or roaring that is purely subjective phantom phenomenon without any sound source. It has been estimated that approximately 10– 15% of the population are affected by chronic tinnitus [1]. The number may be increasing in industrialized and aged countries. About 1 to 3% of the tinnitus population is quite distressing because it causes severe impairments in the quality of life and therewith related high socioeconomic costs (e.g., missing working hours or early retirement). Some tinnitus patients get accustomed to it. At the current stage there is no effective therapy that can reliably eliminate the tinnitus sensation. The principal pathophysiological mechanism causing chronic distressing tinnitus is still poorly understood and unclear
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