Mean sustained pain levels are linked to hemispherical side-to-side differences of primary somatosensory cortex in the complex regional pain syndrome I

Exp Brain Res. 2004 Mar;155(1):115-9. doi: 10.1007/s00221-003-1738-4. Epub 2004 Jan 27.


Chronic back pain as well as phantom-limb pain is characterized by a close relationship between the amount of cortical reorganization and the magnitude of pain. In patients with positively assessed complex regional pain syndrome type I (CRPS I), we found a positive correlation between representational changes of primary somatosensory cortex (SI) and mean sustained pain levels. We investigated seven right-handed patients with CRPS I of one upper limb by means of somatosensory evoked potential (SSEP) mapping. Cortical representation of the CRPS-affected hand was significantly smaller than that of the contralateral healthy hand, giving rise to a substantial side difference. Subjective pain levels experienced over the last 4 weeks were estimated according to the visual analogue scale (VAS). Individual expansion of hand representation contralateral to the CRPS-affected limb was significantly correlated with mean pain intensity. Accordingly, low pain levels were linked to small representational side-to-side differences, while subjects with a distinctive hemispherical asymmetry reported the highest pain levels. Follow-up studies using functional imaging methods might be instrumental in providing a better understanding of this issue.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Brain Mapping / methods*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Pain Measurement / methods*
  • Reflex Sympathetic Dystrophy / physiopathology*
  • Somatosensory Cortex / physiology*
  • Statistics, Nonparametric