Longnecker's Anesthesiology > Part 8. Care of the Chronic Pain Patient > Chapter 90. Mechanisms of Chronic Pain Gary J. Brenner, MD, PhD, and Clifford J. Woolf, MD, PhD

Key Points

"1. Understanding the mechanisms underlying chronic pain requires knowledge of the neuroanatomy, neurochemistry, and neurophysiology of nociception.

2. Generation of pain hypersensitivity results from changes in the function, chemistry, and structure of both the peripheral and central nervous systems.

3. Nociception has a protective function. In contrast, neuropathic and dysfunctional pain are not protective and as such represent or are a manifestation of pathology within the nervous system. In these circumstances, pain can be considered a disease.

4. Chronic pain may result from persistent tissue damage and inflammation leading to an ongoing drive to the nociceptive pathways. It may result from a trigger (usually to the nervous system) that heals, but the pain persists independent of any peripheral drive, or it may be a manifestation of abnormal function of the nervous system independent of any peripheral pathology or lesion to the nervous system.

5. Chronic pain can be categorized into the following broad etiologic groups: nociceptive (associated with an ongoing noxious stimulus), inflammatory (due to ongoing tissue inflammation), neuropathic (resulting from a lesion to the nervous system), or dysfunctional (pain in the absence of a peripheral noxious stimulus, peripheral pathology, or identifiable lesion to the nervous system..."