Chronic pain is pain that persists for more than three months. It may be caused by an ongoing mechanism such as arthritis, persistent nerve root compression, nerve root injury or other ongoing processes. In some cases, the exact cause of the pain cannot be identified and can be associated with changes that have taken place within the nervous system itself. Treatment for chronic pain is based on results of diagnostic tests and previous treatments. Chronic pain patients are managed with medications, injections, chiropractic care, physical therapy, psychological intervention, education, chronic pain management program and/or spinal cord stimulation.