To determine the presence of perceptual sensitization and related brain responses we examined 15 patients with Fibromyalgia syndrome and 15 healthy controls comparable in age and sex.
Multichannel EEG recordings and pain ratings were obtained during the presentation of 800 painful electrical intramuscular [in the muscle] and intracutaneous [in the skin] stimuli to the left m. erector spinae and the left m. extensor digitorum [back and arm]. The stimulus intensity was adjusted to 50% between pain threshold and tolerance.
Detection and pain thresholds were significantly lower in the fibromyalgia syndrome group.
Sensitization occurred for both groups during intramuscular stimulation.
In the EEG data the fibromyalgia syndrome patients showed higher N80 amplitudes compared with the healthy controls.
Arm stimulation and intramuscular stimulation yielded higher N80 and N150 amplitudes compared with intracutaneous stimulation or stimulation of the back.
These results indicate lower pain thresholds in the Fibromyalgia syndrome patients after electrical stimulation and a higher N80 amplitude, both indicative of enhanced sensory processing in this group.
Source: Journal of Clinical Neurophysiology. May 8, 2008. [E-pub ahead of print] PMID: 18469725, by Diers M, Koeppe C, Yilmaz P, Thieme K, Markela-Lerenc J, Schiltenwolf M, van Ackern K, Flor H. Department of Clinical and Cognitive Neuroscience, Central Institute of Mental Health, University of Heidelberg, Mannheim; Orthopedic University Hospital Heidelberg, Heidelberg, Germany; and Department of Anesthesiology and Critical Care Medicine, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany.