What causes chronic pain syndrome (CPS)?

Updated: Jan 14, 2020
  • Author: Manish K Singh, MD; Chief Editor: Stephen Kishner, MD, MHA  more...
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The pathophysiology of chronic pain syndrome (CPS) is multifactorial and complex and still is poorly understood. Some authors have suggested that CPS might be a learned behavioral syndrome that begins with a noxious stimulus that causes pain. This pain behavior then is rewarded externally or internally. Thus, this pain behavior is reinforced, and then it occurs without any noxious stimulus. Internal reinforcers are relief from personal factors associated with many emotions (eg, guilt, fear of work, sex, responsibilities). External reinforcers include such factors as attention from family members and friends, socialization with the physician, medications, compensation, and time off from work.

Patients with several psychological syndromes (eg, major depression, somatization disorder, hypochondriasis, conversion disorder) are prone to developing CPS.

Various neuromuscular, reproductive, gastrointestinal (GI), and urologic disorders may cause or contribute to chronic pain. Sometimes multiple contributing factors may be present in a single patient.

In a study by Alonso-Blanco, a connection was found in women between the number of active myofascial trigger points (MTrPs) and the intensity of spontaneous pain, as well as widespread mechanical hypersensitivity. Nociceptive inputs from these MTrPs may be linked to central sensitization. [8]

A literature review by Gupta et al indicated that in chronic pain patients, primary sensorimotor structural and functional changes are more prominent in females than in males. Males and females differed with regard to the nature and degree of insula changes (with males showing greater insula reactivity), as well as in the extent of anterior cingulate structural changes and in reactivity to emotional arousal. [9]

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