Last updated: Thu, Feb 27, 2025
Varieties of Chronic Pain documents that a large variety of conditions outside of the central nervous system can drive chronic pain. Muscles can develop trigger points that resist even therapeutic injections designed to control them. Joints are subject to degenerative changes, particularly after they have been damaged. Connective tissues do not heal well. A variety of infections, metabolic conditions, and degenerative diseases can cause neuropathy of peripheral sensory neurons. (See Varieties of Chronic Pain.)
Many of these conditions are capable of generating large initial bursts of nociceptive signals and many of them generate many “booster” pulses. This forms a favorable environment for development of central sensitization.
It isn't known exactly how much of pain chronicity is due to events in the periphery and how much is due to processes in the central nervous system. In this section, I will describe the processes of chronic pain that are being discovered in the central nervous system.