Neuroimaging of fibromyalgia: A disease of the brain

Abstract

Introduction: Neuroimaging allows us to deepen and understand the neuropathology of chronic pain. Fibromyalgia (FM) is a multisymptomatic diffuse chronic musculoskeletal pain disorder considered as a Central Sensitization syndrome (CS). Currently, thanks to neuroimaging studies, there is sufficient evidence that such patients present a clear alteration of central pain processing. Objective: To compile and synthesize the cerebral functional and morphological alterations agreed upon and described in FM, through the different study techniques offered by Cranial Magnetic Resonance (MRI). Method: Review of prospective studies, only cranial MRI, recorded in PubMed and Cochrane reviews. Results: Patients with FM, compared to healthy volunteers, show a functional hyperactivation of the neural matrix of pain before different non-nociceptive stimuli. They also show an alteration in the functional connectivity of the endogenous descending inhibitory system and sensory processing, as well as the circuits of self-awareness and attention towards pain. Morphologically refers to the combination of a reduction or increase in gray matter volume in several regions of the neural matrix of pain, with little conclusive data regarding the volume of white matter. Biochemically, an alteration in the level of certain brain metabolites, currently and especially the Glu/Glx complex, is reported in several regions of the neural circuit of pain. Conclusions: Specifically the secondary somatosensory cortex, anterior cingulate cortex and insula appear to play an important role in the central pathophysiology of FM, reinforcing the concept that a failure in the endogenous inhibitory system of pain and/or sensory processing may explain the phenomenon of CS in FM. However, despite the numerous brain alterations described in patients with FM, it is unknown whether the functional and structural alterations objectified with MRI could be a consequence of a chronic nociceptive entry or the cause of the pathogenesis of FM. Nevertheless, the set of neuroimaging results clearly suggest that FM is a disease of the brain.