Intrathecal Therapy for Cancer and Non-Cancer Pain

Background: Intrathecal drug infusion therapy is usually considered when spinal-acting analgesicsor antispasmodics administered via the oral or transdermal routes fail to control patients’ pain or areassociated with unacceptable side effects. The intrathecal administration of centrally acting agentsbypasses the blood-brain-barrier resulting in much higher cerebrospinal fluid (CSF) concentrationswhile using reduced amounts of medication to achieve equipotent doses. The intrathecal approachis associated with higher rates of satisfactory pain relief and lower rates of treatment failures andtechnical complications compared to the epidural route. A paucity of randomized controlled trials(RCTs) has led to concern regarding proper use, selection criteria, and safety of these devices. Costeffectiveness and comparative therapies have now also become a focus of discussion.Objective: The purpose of this systematic review is to evaluate and update the available evidence forthe efficacy and safety of intrathecal infusions used in long-term management (> 6 months) of chronicpain. This paper will not focus on intrathecal administration for spasticity or movement disorders.Study Design: A systematic review of intrathecal infusion through implanted drug delivery devicesfor chronic pain.Methods: Literature search through EMBASE, Medline, Cochrane databases, and systematic reviewsas well as peer-reviewed non-indexed journals from 1980 to December 2010. Studies are assessedusing the Agency for Healthcare Research and Quality (AHRQ) criteria for observational studies and theCochrane Musculoskeletal Review Group criteria for randomized trials.The level of evidence was determined using 5 levels of evidence, ranging from Level I to III with 3subcategories in Level II, based on the quality of evidence developed by the U.S. Preventive ServicesTask Force (USPSTF).Outcome Measures: The primary outcome measure for chronic non-cancer is pain relief (short-termrelief ≤ one-year and long-term > one-year), whereas it is 3 months for cancer. Secondary outcomemeasures of improvement in functional status, psychological status, return to work, and reduction inopioid intake.Results: The level of evidence for this systematic review of non-cancer pain studies meeting theinclusion criteria of continuous use of an intrathecal drug delivery system (IDDS) for at least 12 monthsduration with at least 25 patients in the cohort, is Level II-3 based on USPSTF criteria. The level ofevidence for this systemic review for cancer-related pain studies meeting the inclusion criteria ofcontinuous use of IDDS for at least 3 months duration with at least 25 patients in the cohort is LevelII-2 based on USPSTF criteria.Conclusion: Based on the available evidence, the recommendation for intrathecal infusion systemsfor cancer-related pain is moderate recommendation based on the high quality of evidence andthe recommendation is limited to moderate based on the moderate quality of evidence from nonrandomized studies for non-cancer related pain.Key words: Intrathecal infusion, intrathecal drug delivery device, intrathecal drug delivery system,intraspinal infusion, programmable infusion systems, spinal infusion, intra-spinal infusion devices,baclofen infusion, intrathecal opioids