title: Central sensitization in spinal cord injured humans assessed by reflex receptive fields.
abstract: OBJECTIVE
  To investigate the effects of central sensitization, elicited by intramuscular injection of capsaicin, by comparing the reflex receptive fields (RRF) of spinally-intact volunteers and spinal cord injured volunteers that present presensitized spinal nociceptive mechanisms.
  
  
  METHODS
  Fifteen volunteers with complete spinal cord injury (SCI) and fourteen non-injured (NI) volunteers participated in the experiment. Repeated electrical stimulation was applied on eight sites on the foot sole to elicit the nociceptive withdrawal reflex (NWR). RRF were assessed before, 1min after and 60min after an intramuscular injection of capsaicin in the foot sole in order to induce central sensitization.
  
  
  RESULTS
  Both groups presented RRF expansion and lowered NWR thresholds immediately after capsaicin injection, reflected by the enlargement of RRF sensitivity areas and RRF probability areas. Moreover, the topography of the RRF sensitivity and probability areas were significantly different in SCI volunteers compared to NI volunteers in terms of size and shape.
  
  
  CONCLUSIONS
  SCI volunteers can develop central sensitization, despite adaptive/maladaptive changes in synaptic plasticity and lack of supraspinal control.
  
  
  CONCLUSIONS
  Protective plastic mechanisms may still be functional in SCI volunteers.
authors.affiliation: Center for Sensory-Motor Interaction, Aalborg University, Denmark. Electronic address: jbiurrun@hst.aau.dk.
authors.forename: José Alberto
authors.initials: JA
authors.lastname: Biurrun Manresa
authors.affiliation: Danish Pain Research Center, Aarhus University Hospital, Denmark.
authors.forename: Nanna Susanne Brix
authors.initials: NS
authors.lastname: Finnerup
authors.affiliation: The Spinal Cord Unit, Viborg Hospital, Viborg, Denmark.
authors.forename: Inger Lauge
authors.initials: IL
authors.lastname: Johannesen
authors.affiliation: Clinic for Spinal Cord Injuries, The Neuroscience Centre, Rigshospitalet and Faculty of Health Sciences, University of Copenhagen, Denmark.
authors.forename: Fin
authors.initials: F
authors.lastname: Biering-Sørensen
authors.affiliation: Danish Pain Research Center, Aarhus University Hospital, Denmark.
authors.forename: Troels Staehelin
authors.initials: TS
authors.lastname: Jensen
authors.affiliation: Center for Sensory-Motor Interaction, Aalborg University, Denmark.
authors.forename: Lars
authors.initials: L
authors.lastname: Arendt-Nielsen
authors.affiliation: Center for Sensory-Motor Interaction, Aalborg University, Denmark.
authors.forename: Ole Kæseler
authors.initials: OK
authors.lastname: Andersen
mesh_terms: D000328:Adult; D000368:Aged; D002211:Capsaicin / Q000494:pharmacology; D059333:Central Nervous System Sensitization / Q000187:drug effects / Q000502:physiology*; D004558:Electric Stimulation; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009619:Nociceptors / Q000502:physiology; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects / Q000502:physiology*; D012018:Reflex / Q000187:drug effects / Q000502:physiology*; D018689:Sensory System Agents / Q000494:pharmacology; D013119:Spinal Cord Injuries / Q000503:physiopathology*
chemical_list: D018689:Sensory System Agents; D002211:Capsaicin
keywords: Capsaicin; Central sensitization; Descending control; Nociceptive withdrawal reflex; Reflex receptive fields; Spinal cord injury