Tc-99m-ECD brain perfusion SPECT in hyperalgesic fibromyalgia

Purpose: Neuro-imaging studies with Tc-99m-HMPAO SPECT in fibromyalgia ( FM) patients have reported only limited subcortical hypoperfusion. Tc-99m-ECD SPECT is known to provide better evaluation of areas of high cerebral blood flow and regional metabolic rate. We evaluated a homogeneous group of hyperalgesic patients with FM using Tc-99m-ECD SPECT. The aim of this study was to investigate brain processing associated with spontaneous pain in FM patients. Methods: Eighteen hyperalgesic FM women ( mean age 49 years, range 25 - 63 years; American College of Rheumatology criteria) and ten healthy women matched for age were enrolled in the study. A voxel-by-voxel group analysis was performed using SPM2 ( p< 0.05, corrected for multiple comparisons). Visual Analogue Scale score for pain was 82 +/- 4 at the time of the SPECT study. Results: Compared with control subjects, we observed individual brain SPECT abnormalities in FM patients, confirmed by SPM2 analysis, with hyperperfusion of the somatosensory cortex and hypoperfusion of the frontal, cingulate, medial temporal and cerebellar cortices. Conclusion: In the present study, performed without noxious stimuli in hyperalgesic FM patients, we found significant hyperperfusion in regions of the brain known to be involved in the sensory dimension of pain processing and significant hypoperfusion in areas assumed to be associated with the affective-attentional dimension. As current pharmacological and non-pharmacological therapies act differently on the two components of pain, we hypothesise that SPECT could be a valuable and readily available tool to guide individual therapeutic strategy and provide objective follow-up of pain processing recovery under treatment.