Methadone is approved by the U.S. Food and Drug Administration (FDA) to be used: as an opioid pain reliever, similar to morphine, and for narcotic detoxification to reduce withdrawal symptoms. The dose of methadone that will be used in this study may be slightly higher than the approved dose depending on the subject's weight. However, this dose of methadone is frequently used intraoperatively for pain control in patients undergoing spine surgery at our institution and is within the standard of care. This may vary at different institutions.