Peripheral and central sensitization in remote spinal cord regions contribute to central neuropathic pain after spinal cord injury

Pain. 2009 Dec 15;147(1-3):265-76. doi: 10.1016/j.pain.2009.09.030. Epub 2009 Oct 22.


Central neuropathic pain (CNP) developing after spinal cord injury (SCI) is described by the region affected: above-level, at-level and below-level pain occurs in dermatomes rostral, at/near, or below the SCI level, respectively. People with SCI and rodent models of SCI develop above-level pain characterized by mechanical allodynia and thermal hyperalgesia. Mechanisms underlying this pain are unknown and the goals of this study were to elucidate components contributing to the generation of above-level CNP. Following a thoracic (T10) contusion, forelimb nociceptors had enhanced spontaneous activity and were sensitized to mechanical and thermal stimulation of the forepaws 35 days post-injury. Cervical dorsal horn neurons showed enhanced responses to non-noxious and noxious mechanical stimulation as well as thermal stimulation of receptive fields. Immunostaining dorsal root ganglion (DRG) cells and cord segments with activating transcription factor 3 (ATF3, a marker for neuronal injury) ruled out neuronal damage as a cause for above-level sensitization since few C8 DRG cells expressed AFT3 and cervical cord segments had few to no ATF3-labeled cells. Finally, activated microglia and astrocytes were present in thoracic and cervical cord at 35 days post-SCI, indicating a rostral spread of glial activation from the injury site. Based on these data, we conclude that peripheral and central sensitization as well as reactive glia in the uninjured cervical cord contribute to CNP. We hypothesize that reactive glia in the cervical cord release pro-inflammatory substances which drive chronic CNP. Thus a complex cascade of events spanning many cord segments underlies above-level CNP.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / physiology
  • Activating Transcription Factor 3 / metabolism
  • Animals
  • Behavior, Animal
  • Cell Count / methods
  • Disease Models, Animal
  • Forelimb / physiopathology
  • Ganglia, Spinal / metabolism
  • Ganglia, Spinal / physiology
  • Hyperalgesia / physiopathology
  • In Vitro Techniques
  • Male
  • Neuralgia / etiology*
  • Nociceptors / pathology
  • Nociceptors / physiology
  • Pain Threshold / physiology*
  • Physical Stimulation / methods
  • Rats
  • Rats, Sprague-Dawley
  • Sensory Receptor Cells / physiology
  • Spinal Cord / metabolism
  • Spinal Cord / pathology*
  • Spinal Cord / physiopathology*
  • Spinal Cord Injuries / complications*
  • Spinal Cord Injuries / metabolism
  • Spinal Cord Injuries / pathology*
  • Statistics, Nonparametric


  • Activating Transcription Factor 3
  • Atf3 protein, rat