Chronic Pain Syndrome

Chronic pain is difficult and frustrating to manage, and patients who experience it are often viewed as being undesirable. Perhaps the best way to define chronic pain is to compare and contrast it with acute pain.

Chronic pain syndrome is an abnormal condition in which pain is no longer a symptom of tissue injury, but in which pain and pain behavior become the primary disease processes. Chronic pain syndrome is distinct from chronically or intermittently painful disease in which the patient experiences pain but manifests function and behavior appropriate to the degree of tissue injury.

In chronic pain syndrome, subjective and behavioral manifestations of pain persist beyond objective evidence of tissue injury. Chronically painful conditions can lead to chronic pain syndrome, but not all persons with chronically painful conditions manifest chronic pain behavior and disability.

In chronic pain the original causes are often blurred by subsequent complications of multiple procedures, compensation factors, medication dependency, inactivity, and psychosocial behavior changes.

Etiology of Chronic Pain

Ongoing pathological processes, chronic nervous system dysfunction, or a combination of both processes can cause chronic pain. The patient's perception of the pain is modified by psychological, social, and environmental factors to yield the presenting complaint.

The evaluation of a chronic pain patient should be focused on defining the pain sources as nociceptive, neuropathic, or neuropsychological, while recognizing potential modifiers of the complaints.

In an effort to optimize the care of patients with chronic pain, the International Association for the Study of Pain Subcommittee Association for the Study of Pain (IASP) Subcommittee on Taxonomy has developed a scheme for the coding of chronic pain syndromes.

The IASP classification system further defines five axes based on the anatomical region affected, systemic etiology, temporal characteristics, intensity, and initiating etiology of these diseases. Each of these factors plays an important role in defining the treatment plan.

Somatic

For a Somatic structure to be a source of pain, it must be innervated. If a patient has degenerative disc changes that do not affect the annulus fibrosus, they will usually be painless because the outer annulus is the only portion or the disc that is innervated in adults.

Since nerve endings are stimulated by either mechanical or chemical irritation, any pathological process producing chronic stretching of connective tissues or inflammation of these innervated structures can lead to chronic somatic pain. Examples of this include rheumatoid arthritis, vertebral facet disease, and fibromyalgia

Neuropathic

Neuropathic pain results from alterations in nerve structure of function with or without associated differentiation. It is characterized described as burning, shooting, or electrical in nature and is not associated with any ongoing nociceptive process.

Trauma to or disease of the peripheral nerves can lead to chronic neuropathic pain. This may be the result of neuromas, phantom pain, causalgia, or other sympathetically maintained pain syndromes.

Spinal cord injury or dorsal root ganglion injury can lead to various differentiation pain syndromes, with pain being experienced in an area of sensory loss.

Chronic postlaminectomy back pain can, in some cases, be due to immobilization of dorsal root ganglia by scar tissue. Because of their mechanical sensitivity, the dorsal root ganglia can initiate high-frequency pain signals when stretched. This can perpetuate radicular-type pain.

Thalamic infarcts can cause CENTRAL Pain and postherpetic neuralgia can result from inflammatory injury with dorsal horn. Metabolic derangements, as seen in diabetes, alcoholism, amyloidosis, and hypothyroidism, can lead to painful peripheral neuropathies.

Psychological

Psychogenic pain is often referred as a somatization disorder. The cause lies in an underlying emotional disturbance or stressor that often goes unrecognized by the patient. While pain can be present in any area of the body, he most common forms are tension headaches, angina-like symptoms, colitis, nonspecific vaginal pain, and myofascial pain involving the shoulders and upper and lower extremities.