Second only to the common cold, pain is the most common reason for health care visits. It results in significant personal and social costs to individuals, and economic costs to society. Chronic pain has been estimated to cost more than 100 billion annually in the United States, and its estimated annual cost to European countries ranges from 1.1 to nearly 50 billion Euros (nearly 1.5 billion to over 60 billion dollars). In order to treat pain, clinicians...