title: Effect of intrathecal baclofen on evoked pain perception: an evoked potentials and quantitative thermal testing study.
abstract: OBJECTIVE
  Somatic antinociceptive effects of baclofen have been demonstrated in animal models. We hypothesized that if enhanced thermal or pain sensitivity is produced by loss of gamma-aminobutyric acid (GABA)-ergic tone in the central nervous system, spinal administration of GABA agonists might be predicted to be effective in thermal and/or pain perception changes and pain-related evoked potentials in candidates for intrathecal baclofen (ITB) treatment.
  
  
  METHODS
  Eleven patients with severe spinal cord injury (SCI) who suffered from severe spasticity were evaluated during a 50-μg ITB bolus test. Warm and heat pain thresholds, evoked heat pain perception, and contact heat-evoked potentials (CHEPs) were determined above SCI level from the right and left sides. Nine age- and gender-matched healthy volunteers undergoing repeat testing without any placebo injection served as control group.
  
  
  RESULTS
  In patients, heat pain perception threshold increased, and evoked pain perception and amplitude of CHEPs decreased significantly after ITB bolus application in comparison with baseline (p < 0.005), with no change in warm perception threshold. In controls, no significant changes were observed in repeat testing over time.
  
  
  CONCLUSIONS
  Our findings indicate that ITB modulates heat pain perception threshold, evoked heat pain perception and heat pain-related evoked potentials without inducing warm perception threshold changes in SCI patients. This phenomenon should be taken into account in the clinical evaluation and management of pain in patients receiving baclofen.
authors.affiliation: Institut Guttmann, Institut Universitari de Neurorehabilitació adscrit a la UAB, Barcelona, Spain. hkumru@guttmann.com
authors.forename: H
authors.initials: H
authors.lastname: Kumru
authors.forename: M
authors.initials: M
authors.lastname: Kofler
authors.forename: M C
authors.initials: MC
authors.lastname: Flores
authors.forename: E
authors.initials: E
authors.lastname: Portell
authors.forename: V
authors.initials: V
authors.lastname: Robles
authors.forename: N
authors.initials: N
authors.lastname: Leon
authors.forename: J
authors.initials: J
authors.lastname: Vidal
mesh_terms: D000293:Adolescent; D000328:Adult; D001418:Baclofen / Q000008:administration & dosage / Q000627:therapeutic use*; D005071:Evoked Potentials / Q000187:drug effects*; D005260:Female; D006801:Humans; D007278:Injections, Spinal / Q000379:methods; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000188:drug therapy*; D058748:Pain Perception / Q000502:physiology*; D017288:Pain Threshold / Q000502:physiology; D013119:Spinal Cord Injuries / Q000188:drug therapy* / Q000503:physiopathology; D055815:Young Adult
chemical_list: D001418:Baclofen