Abstract
BackgroundLow frequency repetitive transcranial magnetic stimulation (rTMS) has been proposed as an innovative treatment for chronic tinnitus. The aim of the present study was to elucidate the underlying mechanism and to evaluate the relationship between clinical outcome and changes in cortical excitability. We investigated ten patients with chronic tinnitus who participated in a sham-controlled crossover treatment trial. Magnetic-resonance-imaging and positron-emission-tomography guided 1 Hz rTMS were performed over the auditory cortex on 5 consecutive days. Active and sham treatments were separated by one week. Parameters of cortical excitability (motor thresholds, intracortical inhibition, intracortical facilitation, cortical silent period) were measured serially before and after rTMS treatment by using single- and paired-pulse transcranial magnetic stimulation. Clinical improvement was assessed with a standardized tinnitus-questionnaire.ResultsWe noted a significant interaction between treatment response and changes in motor cortex excitability during active rTMS. Specifically, clinical improvement was associated with an increase in intracortical inhibition, intracortical facilitation and a prolongation of the cortical silent period. These results indicate that intraindividual changes in cortical excitability may serve as a correlate of response to rTMS treatment.ConclusionThe observed alterations of cortical excitability suggest that low frequency rTMS may evoke long-term-depression like effects resulting in an improvement of subcortical inhibitory function.
Highlights
Introduction and Overview of transcranial magnetic stimulation (TMS) PhysicsIn Transcranial Magnetic Stimulation in Neuropsychiatry Edited by: George MS, Belmaker R
Clinical improvement was associated with an increase in intracortical inhibition, intracortical facilitation and a prolongation of the cortical silent period
These results indicate that intraindividual changes in cortical excitability may serve as a correlate of response to repetitive transcranial magnetic stimulation (rTMS) treatment
Summary
Introduction and Overview of TMS PhysicsIn Transcranial Magnetic Stimulation in Neuropsychiatry Edited by: George MS, Belmaker R. Kleinjung T, Eichhammer P, Langguth B, Jacob P, Marienhagen J, Hajak G, Wolf SR, Strutz J: Long-term effects of repetitive transcranial magnetic stimulation (rTMS) in patients with chronic tinnitus. Chistyakov AV, Kaplan B, Rubichek O, Kreinin I, Koren D, Hafner H, Feinsod M, Klein E: Effect of electroconvulsive therapy on cortical excitability in patients with major depression: a transcranial magnetic stimulation study. Langguth B, Eichhammer P, Zowe M, Marienhagen J, Spiessl H, Hajak G: Neuronavigated transcranial magnetic stimulation and auditory hallucinations in a schizophrenic patient: Monitoring of neurobiological effects. Chistyakov AV, Kaplan B, Rubichek O, Kreinin I, Koren D, Feinsod M, Klein E: Antidepressant effects of different schedules of repetitive transcranial magnetic stimulation vs clomipramine in patients with major depression: relationship to changes in cortical excitability.
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