Cerebral Event Related Potentials and Heat Pain Thresholds in Fibromyalgia Syndrome

Abstract

Objectives: To assess the pain threshold to heat and subsequent event related cerebral evoked potential in patients with fibromyalgia and controls. Methods: Eleven females with fibromyalgia [mean age 28.3 years] and 11 subjects without symptoms or signs of fibromyalgia [mean age 26.6 years] were identified. Using CO₂ laser heat stimulation as controls but pain threshold was significantly reduced. The latency between the onset of the painful heat stimulus and the CNS evoked response was the same in FS subjects and controls, however, FS subjects displayed significant change in peak-to-peak amplitude of the event related CNS evoked response. There was a strong association between neurogenic flare response and the nociceptor evoked cerebral response. Conclusions: This study provides further evidence of an altered pain threshold to a variety of noxious modalities in FS implying a major role for the polymodal nociceptors in the clinical expression of this syndrome.

KEYWORDS:

• Fibromyalgia
• fibrositis
• pain threahold
• event related EEG