Obviously we know what causes some chronic pain, such as in arthritis, cancer, many traumatic injuries and some chronic illnesses. Causes of chronic pain can include inflammation, disease progression, scar tissue around a nerve root, instability of the spinal vertebrae, and a damaged nerve (or neuropathic pain). For most types of chronic pain, however, there is no determinable reason from a medical standpoint why pain persists.

Chronic pain is widely believed to be a devastating neurological disorder. Most research studies of chronic pain have focused on signals in the spinal cord and in the peripheral nerves, which carry pain messages from the limbs and other parts of the body to the spinal cord, which then relays the messages to the brain. Studies suggest that the brain not only receives pain signals from the spinal cord but also undergoes significant changes in neuronal connections that may permanently strengthen its reactions to those signals. The neuronal changes that underlie chronic pain are similar in many ways to those that occur when long-term memories are stored. Scientists believe these changes are key to the development of chronic pain.

The dramatic neuronal changes that occur with injury and persistent pain underscore that chronic pain should be considered a disease of the nervous system, not just prolonged acute pain or a symptom of an injury. Thus, scientists hope that therapies directed at preventing the long-term changes that occur in the nervous system will prevent the development of these chronic pain conditions.