Chronic pain, is pain that has lasted for longer than a 6 month period. After that amount of time, the brain becomes used to receiving the feeling of pain from the nerves that are affected. The brain sends signals to the nerves, and when the nerves respond, the feeling is internalized.
With chronic pain, the feeling is constant so the brain becomes used to having it there. This can make it challenging to get the brain to stop feeling the pain – even when the pain itself is gone.