Herring EZ, et al. - The long-term efficacy of intrathecal drug delivery systems (IDDS) in patients with complex regional pain syndrome (CRPS) was determined. Among 62 patients who were implanted primarily for CRPS-related pain, 26 had four or more years of continuous follow-up. A detailed follow-up of these 26 patients, tracking oral opiate intake, pain scores, and intrathecal pump settings revealed no long-term decreases in oral opioid intake in correlation with intrathecal opioid dose. Over the four-year follow-up, a decrease in oral opioid intake was observed with ziconotide, and an increase in oral opioid intake was noted in correlation with bupivacaine.