Fibromyalgia pain: do we know the source?

PURPOSE OF REVIEW: Fibromyalgia Syndrome (FMS) is a chronic pain condition of unknown origin. Multiple abnormalities have been described, including peripheral tissue and central nervous system changes. The relation of these mechanisms, however, is likely bidirectional. FMS pain clearly depends on peripheral nociceptive input as well as abnormal central pain processing. This review will focus on the role of peripheral nociceptive input for pain in FMS.

RECENT FINDINGS: There is strong evidence for abnormal central pain processing in FMS. Sensitized spinal cord neurons in the dorsal horn are responsible for augmented pain processing of nociceptive signals from the periphery. In addition, glial activation, possibly by cytokines and excitatory amino acids may play a role in the initiation and perpetuation of this sensitized state.

SUMMARY: Nociceptive input clearly plays an important role in FMS. Acute or repetitive tissue injury has been associated with FMS pain. Cytokines related to such injuries may be responsible for long-term activation of spinal cord glia and dorsal horn neurons, thus resulting in central sensitization. A better understanding of these important neuro-immune interactions may provide relevant insights into future effective therapies.