The problem with chronic pain. Therapy for acute pain (e.g., acute inflammation, trauma, post-surgical pain) is overall excellent. However, in chronic pain (e.g., neuropathic pain, fibromyalgia, complex regional pain syndrome), therapy is poor. This group thus falls into a zone (circles) of "therapeutic failure" or "therapeutic impasse" where multiple therapies are tried with overall little success. Functional imaging appears poised to open up new approaches to the understanding of chronic pain conditions. An improved basic understanding of the mechanisms underlying chronic pain is likely to suggest new avenues for the development of novel pharmacotherapies.