Complex regional pain syndrome (CRPS) is a type of chronic pain. In most cases, CRPS develops in an arm or leg that has been previously injured and may result in unexplained pain that won’t go away. CRPS may be severe and it may spread. Treatment for CRPS may involve physical therapy and psychotherapy. Treatment may also include oral medications and a nerve block, which can deliver medication into the fluid around the spinal cord as needed.

Phantom limb pain or “phantom pain” refers to painful sensations that feel like they are coming from a missing limb. This condition is common among amputees and may become chronic. Treatment may include medications, nerve stimulation, and other therapeutic techniques.