Regional cerebral blood flow between primary and concomitant fibromyalgia patients: a possible way to differentiate concomitant fibromyalgia from the primary disease

Objectives: Technetium-99m ethyl cysteinate dimer (Tc-99m ECD) brain single photon emission computed tomography (SPECT) has been used to detect abnormal regional cerebral blood flow (rCBF) in women with primary fibromyalgia (FM). The main aim of this study was to investigate the rCBF deficit in concomitant FM patients and compare it with primary FM. Methods: An observational study was designed to analyse the SPECT findings in 92 female patients recruited from January 2002 to January 2004. Differences in the rCBF hypoperfusive areas between 49 primary and 29 concomitant FM patients were assessed in different areas of the brain using the chi(2)-test for statistical significance. Results: Tc-99m ECD brain SPECT in 71 FM patients revealed heterogeneous rCBF in comparison to the homogeneous scan in 14 control patients. The most prominent rCBF hypoperfusive region in both primary and concomitant FM groups was the left temporoparietal area, followed by the thalamus, right temporoparietal, frontal, and basal ganglia areas. Differences in rCBF hypoperfusion in these areas for both FM groups were not significant (all p>0.5). Conclusions: Reduced rCBF at cortical regions, in addition to previously reported areas at the thalamus and the subcortical nucleus, in FM patients was demonstrated in this study. The perfusion deficit areas were similar between primary and concomitant FM when the underlying disease activity was quiescent. The feasibility of using this neuroimaging study to differentiate FM from the primary disease, such as rheumatoid arthritis (RA)associated depression and neuropsychiatric lupus, should be considered.