Both pain and EEG response to cold presser stimulation occurs faster in fibromyalgia

Pain-evoked brain potentials elicited by laser stimulation have been repeat edly shown to be abnormal in fibromyalgia syndrome. However, to our knowled ge this is the first study assessing enduring (cold presser) pain and corre lated EEG changes in fibromyalgia. EEG power and subjective pain ratings du ring the cold presser test were analyzed and contrasted with tasks not invo lving sensory stimulation (rest, mental arithmetic and pain imagery) in 20 patients with fibromyalgia and 21 healthy control subjects. Fibromyalgia pa tients both perceived pain and judged pain as intolerable earlier than cont rol subjects, while pain intensity ratings and EEG power changes during sub jective awareness of pain were similar in both groups. In patients and cont rol subjects, pain was correlated with a rise in delta, theta and beta powe r. EEG power spectra during pain imagery and mental arithmetic were signifi cantly different from those observed during the cold plessor test. In concl usion, fibromyalgia patients seem to process painful stimuli abnormally in a quantitative sense, thus producing both the sensation of pain, as well as the associated EEC patterns, much earlier than control subjects. However, the quality of the pain-associated EEG changes seems similar. (C) 2000 Else vier Science Ireland Ltd. All rights reserved.