Chronic Pain Syndromes

Chronic pain generally persists or recurs for longer than 3 months. It is not simply acute pain that has lasted too long: ongoing nociceptive input, altered nervous-system processing, sleep disruption, mood, stress, social circumstances, and learned protective behaviors can interact to maintain pain and disability. The term chronic primary pain is used when pain has been present for at least 3 months, causes significant emotional distress or functional disability, and is not better explained by another diagnosis. A patient may still have biological findings, depression, anxiety, trauma-related symptoms, or substance-use concerns. “Primary” does not mean imaginary, and it does not exclude contributing pathology. Chronic secondary pain is associated with an identifiable disease, injury, or other condition that better accounts for the pain. Persistent pain can increase the excitability of pain-processing pathways and reduce inhibitory control. This altered processing may produce pain from normally nonpainful contact, an exaggerated response to a mildly painful stimulus, or pain that extends beyond the original tissue site. These findings can occur in conditions such as fibromyalgia, chronic musculoskeletal pain, neuropathic pain, and complex regional pain...