The Clinical journal of pain
-
Pain related to fibromyalgia may consist of a complex interaction of nociceptive, neuropathic, dysregulatory central nervous system and psychosomatic mechanisms. Nociceptor pain is based on the excitation of nervous sensors specialized to signal potentially harmful stimuli, i.e., the nociceptors. Metabolic deficiencies in muscle and neurogenic inflammation induced by the release of substance P and other neuropeptides from the peripheral nerve endings may result in chemical sensitization of nociceptors and an ensuing hyperalgesia particularly present in tender points. ⋯ Persistent abnormal spinal reflex transmission due to, e.g., peripheral trauma or inappropriate postural habits may result in a vicious circle between muscle hypertension and pain. Similarly, a defective sympathetic control may result in disturbed microcirculation and nociceptor excitation (e.g., in sympathetic algodystrophy). Many symptoms of pain in fibromyalgia (trigger points, pain referral, pain associated with muscle spasm or neurogenic joint immobilization) can be attributed to abnormal control mechanisms in a complex cybernetic system.(ABSTRACT TRUNCATED AT 250 WORDS)