Chronic pain syndromes

Chronic pain is one of the most common reasons for seeing a primary care physician.

Classification of chronic pain may be based on major pain features or by body region: myofascial, musculoskeletal (mechanical), neuropathic, fibromyalgia, and chronic headache syndromes.

One in three patients over the age of 65 years is affected by chronic pain, often due to arthritis, osteoporosis with fractures and/or lumbar spinal stenosis. These conditions are treatable and should not be considered part of the normal aging process. Untreated chronic pain in older patients can result in depression, poor quality of life, and loss of independence.

Some treatments, such as stretching exercises, relaxation techniques, antidepressants, and anticonvulsant drugs, are beneficial for a wide variety of chronically painful conditions.

Opioids should not be used as first-line or routine therapy for chronic pain; evidence for effectiveness is limited, and they are associated with risk of adverse events such as overdose, misuse, fractures from falls, hormonal changes, and increased sensitivity to pain.

Acute pain is a common consequence of injury or illness, generally decreasing shortly after onset and resolving once healing is complete. Since healing occurs over a maximum of 3 months, pain persisting longer than 3 months is deemed chronic pain or persistent pain. Chronic pain may also occur in patients with ongoing degenerative illnesses, such as rheumatoid arthritis, or other chronic conditions, like migraine or neuropathic pain. Neuropathic pain is characterized by allodynia and hyperalgesia. Allodynia is the perception of non-noxious stimuli as painful. In hyperalgesia, noxious stimuli produce exaggerated or prolonged pain. Pain severity may fluctuate in patients with chronic pain, with periods of increased pain or pain flares occurring either in relation to increased activity or stress, or insidiously. Chronic pain occurs due to persistent activation of neural pain pathways and muscle spasm. [Figure caption and citation for the preceding image starts]: Acute pain occurs with trauma or illness, decreasing during healing and resolving within 3 months. Chronic pain persists after healing is completed, due to continued activation of neural pain pathways and muscle spasmFrom Marcus DA. Headache and chronic pain syndromes. The case-based guide to targeted assessment and treatment. Totowa, NJ: Humana Press; 2007 [Citation ends].