INTRODUCTION: Pain is a subjective experience that is difficult to evaluate due to its varied expression. Currently, functional magnetic resonance imaging (fMRI) can reveal the brain's response to painful stimuli. OBJECTIVE: To evaluate the brain's response to pain in patients with chronic generalized essential pain diagnosed with fibromyalgia (FM). SUBJECTS AND METHODS: Pain stimulus through mechanical pressure was administered to 15 patients with FM and to 22 control subjects while fMRI was carried out. Several attempts at activation were performed, varying the pressure exerted on a 2 cm2 surface of the thumb. RESULTS: During acquisition of fRMI, none of the control subjects experienced significant discomfort when mechanical pressure of 4 kg was applied. However, all patients except one reported moderate-severe pain with the same stimulus. fMRI revealed that with slight pressure (4 and 5 kg), activation of areas other than the primary sensory-motor area contralateral to the stimulated thumb was exceptional in controls. However, 5 patients (p = 0.027) at 4 kg of pressure and seven (p = 0.030) at 5 kg of pressure showed activation of brain regions known to be mediators of pain response (primary sensory-motor area, parietal cortex, insula, and anterior cingulum). CONCLUSIONS: The results of this study suggest that in a significant proportion of patients diagnosed with FM and with a low pain threshold, there is a consistent brain response to low-intensity mechanical stimuli while in another proportion of patients, the response of the brain to painful stimuli is similar to that of control subjects.
|Publication status||Published - 1 Jan 2006|
- Anterior cingulum
- Chronic pain
- Functional magnetic resonance imaging
- Pain perception