Central amplification and fibromyalgia: disorder of pain processing

Fibromyalgia (FM), a complex chronic pain disorder affecting a heterogeneous patient population, is an area of active basic and clinical research. Although diagnostic criteria for FM have been available for 2 decades, there remains no definitive diagnostic and no consensus regarding its etiology. Accumulating evidence suggests the underlying cause of FM pain results from abnormal pain processing particularly in the central nervous system rather than from dysfunction in peripheral tissues where pain is perceived. In this review, we examine recent studies investigating abnormalities in central pain processing as a component of FM in both preclinical models of generalized muscle hypersensitivity and clinical research in patients with FM. We focus our discussion on two areas where strong evidence exists for abnormalities in sensory signaling: the reduction of descending control, including suppression of descending inhibitory pathways and/or enhancement of descending facilitatory pathways, and changes in key neurotransmitters associated with central sensitization. Finally, we discuss currently available pharmacological treatments indicated for the management of pain in FM patients, based on their proposed mechanism of action and efficacy.