title: Abnormal reactivity of the primary somatosensory cortex during the experience of pain in complex regional pain syndrome: a magnetoencephalograhic case study.
abstract: A 49-year-old male worker developed persistent pain in his left wrist after work strain injuries. Clinical symptoms met with criteria for Complex Regional Pain Syndrome (CRPS) type I. In the present study, the effect of the experience of pain on the somatotopy of the primary cortical hand representation was investigated. Somatosensory evoked magnetic fields (SEF) elicited by non-painful tactile stimulation at the index finger of the affected and the unaffected hand were recorded when experiencing pain elicited by a moderate physical load condition (holding a 1.6 kg object in the hand). It was shown that MEG and subjective responses to innocuous tactile stimuli were reduced when simultaneous nociceptive stimulation was applied. These findings suggest a gating effect in the central nervous system elicited by concurrent simultaneous information from two different somatosensory modalities (pain and tactile). The results revealed the existence of nociceptive-induced plastic changes in the central nervous system associated with CRPS type I.
authors.affiliation: Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Germany. larbig@uni-tuebingen.de
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Larbig
authors.forename: Pedro
authors.initials: P
authors.lastname: Montoya
authors.forename: Christoph
authors.initials: C
authors.lastname: Braun
authors.forename: Niels
authors.initials: N
authors.lastname: Birbaumer
mesh_terms: D001931:Brain Mapping; D020918:Complex Regional Pain Syndromes / Q000473:pathology / Q000503:physiopathology / Q000523:psychology; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D007839:Functional Laterality; D006225:Hand / Q000294:innervation; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000209:etiology*; D010147:Pain Measurement / Q000379:methods; D017288:Pain Threshold / Q000502:physiology; D013003:Somatosensory Cortex / Q000503:physiopathology*