Both pain and EEG response to cold pressor stimulation occurs faster in fibromyalgia patients than in control subjects.
Pain-evoked brain potentials elicited by laser stimulation have been repeatedly shown to be abnormal in fibromyalgia syndrome. However, to our knowledge this is the first study assessing enduring (cold pressor) pain and correlated EEG changes in fibromyalgia. EEG power and subjective pain ratings during the cold pressor test were analyzed and contrasted with tasks not involving sensory stimulation (rest, mental arithmetic and pain imagery) in 20 patients with fibromyalgia and 21 healthy control subjects. Fibromyalgia patients both perceived pain and judged pain as intolerable earlier than control subjects, while pain intensity ratings and EEG power changes during subjective awareness of pain were similar in both groups. In patients and control subjects, pain was correlated with a rise in delta, theta and beta power. EEG power spectra during pain imagery and mental arithmetic were significantly different from those observed during the cold pressor test. In conclusion, fibromyalgia patients seem to process painful stimuli abnormally in a quantitative sense, thus producing both the sensation of pain, as well as the associated EEG patterns, much earlier than control subjects. However, the quality of the pain-associated EEG changes seems similar.
Stevens
A
A
Department of Psychiatry, University of Tübingen, Universitätsklinik für Psychiatrie und Psychotherapie, Osianderstr. 24, 72076, Tübingen, Germany. andreas.stevens@med.uni-tuebingen.de
Batra
A
A
Kötter
I
I
Bartels
M
M
Schwarz
J
J
D003080:Cold Temperature; D004569:Electroencephalography; D005260:Female; D005356:Fibromyalgia / Q000150:complications*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000150:complications* / Q000175:diagnosis*; D010147:Pain Measurement; D012720:Severity of Illness Index; D013997:Time Factors