Mean sustained pain levels are linked to hemispherical side-to-side differences of primary somatosensory cortex in the complex regional pain syndrome I.
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.
Pleger
Burkhard
B
Department of Neurology, BG-Kliniken Bergmannsheil, Ruhr University Bochum, Buerkle-de-la-Camp Platz 1, 44789, Bochum, Germany.
Tegenthoff
Martin
M
Schwenkreis
Peter
P
Janssen
Frank
F
Ragert
Patrick
P
Dinse
Hubert R
HR
Völker
Birgit
B
Zenz
Michael
M
Maier
Christoph
C
D000328:Adult; D001931:Brain Mapping / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement / Q000379:methods*; D012019:Reflex Sympathetic Dystrophy / Q000503:physiopathology*; D013003:Somatosensory Cortex / Q000502:physiology*; D018709:Statistics, Nonparametric