Most people are familiar with acute pain – a painful sensation that comes on suddenly that is triggered by the nervous system.  However, chronic pain is quite different.  Chronic pain continues for weeks, months, and even years.  Such pain may be due to an initial acute injury or another ongoing sense of pain (e.g., arthritis, cancer).  Although, many people experience chronic pain without any previous injury or condition.

The most common complaints of chronic pain include: headache, low back pain, cancer pain, arthritis pain, neurogenic pain (pain resulting from damage to the peripheral nerves or to the central nervous system itself), and psychogenic pain (pain not due to past disease or injury or any visible sign of damage inside or outside the nervous system).

Fortunately, the majority of people with chronic pain can be helped if they understand all the causes of pain and the many and varied steps that can be taken to undo what chronic pain has done. Scientists believe that advances in neuroscience will lead to more and better treatments for chronic pain in the years to come.

Source:  National Institute of Neurological Disorders and Stroke (National Institutes of Health)