Imagine you are a doctor treating a patient who has been in nearly constant pain for four years, ever since the day he sprained his ankle stepping off a curb. Physical therapy only briefly dulled the agony. Painkillers were not much better, and the most effective drugs made your patient exhausted and constipated. He is now depressed, sleeping poorly and having difficulty concentrating. As you talk with him, you realize that his thinking also seems impaired. Your exam confirms that the original injury has healed. Only pain and its consequences remain—and your options for helping this man are running out.