title: Variable changes in PET activity before and after rTMS treatment for tinnitus.
abstract: OBJECTIVE
  The objective was to determine whether low-frequency repetitive transcranial magnetic stimulation (rTMS) improves tinnitus by decreasing neural activity in auditory processing regions of the temporal cortex and the utility of positron emission tomography (PET) for targeting treatment.
  
  
  METHODS
  Randomized, sham-controlled crossover.
  
  
  METHODS
  Patients received a five-day course of active and sham 1-Hz rTMS (1800 pulses at 110% of motor threshold) to the temporal cortex, with a week separating active and sham treatment. Visual analogue ratings of tinnitus loudness (VARL) were assessed at baseline and the end of each treatment week; regional brain blood flow (rBBF) and glucose metabolism (via PET) were measured before and after treatment in regions of interest (ROI) beneath the stimulating coil and control sites.
  
  
  RESULTS
  The VARL for both ears significantly decreased after active but not sham treatment. Responders comprised 43% of patients, experiencing at least a 33% drop in tinnitus loudness. The site most consistently associated with a positive response was the secondary auditory cortex (Brodmann Area 22) in either hemisphere. PET asymmetries were variable across patients and not always accessible to rTMS. Whereas PET activity decreased significantly beneath the stimulating coil following active treatment, similar changes occurred at control sites and after sham stimulation. Change in tinnitus perception did not correlate significantly with change in PET activity at the treatment site ROI.
  
  
  CONCLUSIONS
  Active TMS led to a significant reduction in tinnitus loudness, but PET scans failed to support the hypothesis that low-frequency rTMS improves tinnitus by reducing cortical activation at the stimulation site, questioning the utility of PET for targeting rTMS.
authors.affiliation: Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA. msmennemeier@uams.edu
authors.forename: Mark
authors.initials: M
authors.lastname: Mennemeier
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: Chelette
authors.forename: Shawn
authors.initials: S
authors.lastname: Allen
authors.forename: Twyla B
authors.initials: TB
authors.lastname: Bartel
authors.forename: William
authors.initials: W
authors.lastname: Triggs
authors.forename: Timothy
authors.initials: T
authors.lastname: Kimbrell
authors.forename: Joseph
authors.initials: J
authors.lastname: Crew
authors.forename: Tiffany
authors.initials: T
authors.lastname: Munn
authors.forename: Ginger J
authors.initials: GJ
authors.lastname: Brown
authors.forename: John
authors.initials: J
authors.lastname: Dornhoffer
mesh_terms: D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000378:metabolism*; D018592:Cross-Over Studies; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D049268:Positron-Emission Tomography; D012039:Regional Blood Flow / Q000502:physiology*; D013702:Temporal Lobe / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D014012:Tinnitus / Q000000981:diagnostic imaging* / Q000628:therapy*; D050781:Transcranial Magnetic Stimulation
chemical_list: D001786:Blood Glucose; D019788:Fluorodeoxyglucose F18