Neuroimaging of fibromyalgia.

The primary symptom of fibromyalgia is widespread pain. This symptom is accompanied by secondary symptoms, such as cognitive difficulties and sensitivity to painful stimulation, and by numerous co-morbidities. The first neuroimaging studies addressed the primary symptom by examining differences between patients and controls using single-photon-emission-computed tomography (SPECT). Subsequent studies focussed on the secondary symptom of increased sensitivity to painful stimulation. Functional MRI (fMRI) studies using the blood-oxygen-level-dependent (BOLD) method to assess brain activation demonstrated augmented sensitivity to painful pressure and the association of this augmentation with variables such as depression and catastrophising. These studies have also assessed brain processes associated with cognitive dysfunction. Neuroimaging studies of fibromyalgia have now come full circle, using new techniques to provide information about differences that may relate to underlying mechanisms and the primary symptom of widespread pain. Using a wide array of techniques, these studies have found differences in opioid receptor binding, concentration of metabolites associated with neural processing in pain-related regions and differences in functional brain networks and in regional brain volume and in white-matter tracks. This array of neuroimaging techniques continues to provide increasing information about supraspinal mechanisms associated with fibromyalgia that will aid in diagnosis, including identification of diagnostic subgroups, the development of new efficacious treatments that address both causes and symptoms and the matching of patients to treatments.