Extended-release Epidural Morphine for Acute Post-operative Analgesia Following Selective Dorsal Rhizotomy in Children

The purpose of this proposal is to improve the investigators' current Selective Dorsal Rhizotomy (SDR) analgesia protocol by eliminating or minimizing the use of fentanyl in the post-operative period. Children undergoing SDR for spastic cerebral palsy have significant post-operative pain. The procedure requires dissection of the lumbar back musculature and removal of the L1 lamina (the bony posterior part of the vertebra). The majority of the operation is intradural, and a water-tight dural closure at the termination of the operation is critical in order to prevent leakage of cerebrospinal fluid (CSF) from the wound. In fact, these children must remain flat on their back for 48 hours to allow the dural incision to heal prior to mobilization. Thus, adequate pain control is essential not only for patient comfort, but also to prevent agitation and additional stress on the dural closure. Currently, the investigators' patients undergoing SDR are treated for 48 hours with scheduled intravenous (IV) narcotic (continuous fentanyl infusion at 0.5-2.0 μg/kg/hour) in addition to the sedative/muscle relaxant Valium (0.2 mg/kg IV every 4 hours for 24 hours, then every 6 hours for 24 hours). The IV fentanyl, and to a lesser degree Valium, carries a real risk of hypotension and respiratory depression and requires frequent dose adjustments to achieve adequate analgesia. By improving the current SDR analgesia protocol, the investigators hope to maximize patient safety and comfort while maintaining the effectiveness of the operation by minimizing the risk of CSF leak.