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| ABNORMAL PAIN PERCEPTION AND FUNCTIONAL BRAIN ACTIVITY IN WOMEN WITH FIBROMYALGIA Laurence A. Bradley, Ph.D., Division of Clinical Immunology and Rheumatology, University of Alabama, Birmingham, Alabama Fibromyalgia (FM) is a disorder characterized by functional abnormalities of the hypothalamic pituitary-adrenal (HPA) axis, widespread pain, and exquisite sensitivity to pressure stimulation at specific anatomic sites (i-e., tender points). The prevalence of FM in the population is 2% - 3%; about 90% of FM sufferers are women. This presentation will review the results of several investigations of pain perception and functional brain activity in women with FM. The major findings are that women with FM, relative to healthy controls, (1) produce significantly lower pain thresholds and significantly higher scores on an index of sensory discrimination ability; (2) exhibit significantly higher cerebrospinal fluid (CSF) levels of substance P; (3) show significantly lower levels of functional brain activity in the caudate nucleus during resting conditions. These findings are independent of health care seeking behavior and psychological distress. Preliminary data also will be presented which suggests that women with FM, compared to controls, generally show a smaller increase in thalamic functional activity in response to painful stimulation. Together, these findings indicate that abnormal pain perception in women with FM is associated with elevated CSF substance P levels and diminished functional brain activity in the caudate nucleus and thalamus. These abnormalities are similar to those found in patients with neuropathic pain syndromes. An explanatory model will be presented which suggests that genetic susceptibility to neuroendocrine abnormalities and exposure to precipitating events such as physical injury or emotional trauma may play important roles in the etiopathogenesis of abnormal pain perception in women with FM.
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