title: Differential NMR spectroscopy reactions of anterior/posterior and right/left insular subdivisions due to acute dental pain.
abstract: OBJECTIVE
  The insular cortex has an important role within the cerebral pain circuitry. The aim of this study was to measure metabolic alterations by MR spectroscopy due to experimentally induced trigeminal pain in the anterior/posterior and right/left insular subdivisions.
  
  
  METHODS
  Sixteen male volunteers were investigated using magnetic resonance (MR) spectroscopy before, during and after experimentally induced dental pain. Biphasic bipolar electric current pulses of 1 ms duration were administered based on the subjectively determined pain threshold. Volunteers were instructed to rate every stimulus using a MR compatible rating scale.
  
  
  RESULTS
  Due to the pain stimulation a significant absolute increase in glutamate (Glu, F = 6.1; P = 0.001), glutamine (Gln, F = 11.2; P = 0.001) as well as glutamate/glutamine (Glx, F = 17.7; P = 0.001) were observed, whereas myo-inositol (mI, F = 9.5;P = 0.001) showed a significant drop. Additionally, these metabolites showed a significant effect towards lateralisation, meaning that metabolic concentration differed either in left or right insular subdivision. Creatine demonstrated also an absolute significant decrease during stimulation (F = 2.8; P = 0.022) with a significant anterior-posterior difference (F = 40.7; P = 0.001).
  
  
  CONCLUSIONS
  Results confirm that the insular cortex is a metabolically high active region in pain processing within the brain. Quantitative metabolic changes show that there is a distinct but locally diverse neurometabolic activity under acute pain. The known cytoarchitectonic subdivisions show different metabolic reactions and give new insights into pain-processing physiology.
authors.affiliation: Department of Radiology, Cantonal Hospital Winterthur, Brauerstrasse 15, 8401 Winterthur, Switzerland. agutzeit@bluewin.ch
authors.forename: Andreas
authors.initials: A
authors.lastname: Gutzeit
authors.forename: Dieter
authors.initials: D
authors.lastname: Meier
authors.forename: Johannes M
authors.initials: JM
authors.lastname: Froehlich
authors.forename: Klaus
authors.initials: K
authors.lastname: Hergan
authors.forename: Sebastian
authors.initials: S
authors.lastname: Kos
authors.forename: Constantin
authors.initials: C
authors.lastname: V Weymarn
authors.forename: Kai
authors.initials: K
authors.lastname: Lutz
authors.forename: Dominik
authors.initials: D
authors.lastname: Ettlin
authors.forename: Christoph A
authors.initials: CA
authors.lastname: Binkert
authors.forename: Jochen
authors.initials: J
authors.lastname: Mutschler
authors.forename: Sabine
authors.initials: S
authors.lastname: Sartoretti-Schefer
authors.forename: Mike
authors.initials: M
authors.lastname: Brügger
mesh_terms: D059787:Acute Pain / Q000175:diagnosis / Q000378:metabolism; D000328:Adult; D001224:Aspartic Acid / Q000378:metabolism; D001923:Brain Chemistry / Q000502:physiology; D002540:Cerebral Cortex / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism*; D006801:Humans; D007294:Inositol / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D017288:Pain Threshold; D011446:Prospective Studies; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D014098:Toothache / Q000175:diagnosis / Q000378:metabolism*; D055815:Young Adult
chemical_list: D005973:Glutamine; D001224:Aspartic Acid; D018698:Glutamic Acid; D007294:Inositol