title: Changes in motor cortex excitability associated with temporal repetitive transcranial magnetic stimulation in tinnitus: hints for cross-modal plasticity?
abstract: BACKGROUND
  Motor cortex excitability was found to be changed after repetitive transcranial magnetic stimulation (rTMS) of the temporal cortex highlighting the occurrence of cross-modal plasticity in non-invasive brain stimulation. Here, we investigated the effects of temporal low-frequency rTMS on motor cortex plasticity in a large sample of tinnitus patients. In 116 patients with chronic tinnitus different parameters of cortical excitability were assessed before and after ten rTMS treatment sessions. Patients received one of three different protocols all including 1 Hz rTMS over the left temporal cortex. Treatment response was defined as improvement by at least five points in the tinnitus questionnaire (TQ). Variables of interest were resting motor threshold (RMT), short-interval intra-cortical inhibition (SICI), intracortical facilitation (ICF), and cortical silent period (CSP).
  
  
  RESULTS
  After rTMS treatment RMT was decreased by about 1% of stimulator output near-significantly in the whole group of patients. SICI was associated with significant changes with respect to treatment response. The group of treatment responders showed a decrease of SICI over the course of treatment, the group of non-responders the reverse pattern.
  
  
  CONCLUSIONS
  Minor RMT changes during rTMS treatment do not necessarily suggest the need for systematic re-examination of the RMT for safety and efficacy issues. Treatment response to rTMS was shown to be related to changes in SICI that might reflect modulation of GABAergic mechanisms directly or indirectly related to rTMS treatment effects.
authors.affiliation: Department of Psychiatry and Psychotherapy, University Regensburg, Universitätsstraße 84, 93053 Regensburg, Germany. martin.schecklmann@medbo.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Schecklmann
authors.forename: Michael
authors.initials: M
authors.lastname: Landgrebe
authors.forename: Tobias
authors.initials: T
authors.lastname: Kleinjung
authors.forename: Elmar
authors.initials: E
authors.lastname: Frank
authors.forename: Philipp G
authors.initials: PG
authors.lastname: Sand
authors.forename: Rainer
authors.initials: R
authors.lastname: Rupprecht
authors.forename: Peter
authors.initials: P
authors.lastname: Eichhammer
authors.forename: Göran
authors.initials: G
authors.lastname: Hajak
authors.forename: Berthold
authors.initials: B
authors.lastname: Langguth
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009433:Neural Inhibition; D009473:Neuronal Plasticity; D014012:Tinnitus / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy*; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D016896:Treatment Outcome; D055815:Young Adult