Neuraxial techniques for cancer pain: an opinion about unresolved therapeutic dilemmas.

BACKGROUND AND OBJECTIVES Epidural and intrathecal techniques are well established for minimizing cancer pain. However, several issues remain unresolved. METHODS A review of studies published in the last 10 years regarding neuraxial techniques in cancer pain management was made. The following issues were assessed: appropriate indications; techniques and delivery systems; conversion from systemic to spinal administration; route and modes of administration; choice of opioids, analgesic response and adverse effects of opioids; use of local anesthetics; use of adjuvants; technical complications; and possible problems only recognized at home. RESULTS Indications for the use of neuraxial opioids include patients treated with systemic opioids who received effective pain relief but with unacceptable side effects or unsuccessful treatment despite escalating doses with sequential, strong opioid drug trials. The choice of exteriorized or implanted delivery systems is based on different clinical considerations. The use of externalized, tunnelled intrathecal catheters has not been proven to be associated with higher rates of complications, and they may be easier to place and use at home in debilitated patients late in the course of their disease. Intrathecal administration has a lower incidence of catheter occlusion, lower malfunction rate, lower dose and volume requirements, and more effective pain control. Advantages of continuous infusion techniques are more evident when using local anesthetics, because intermittent administration of bupivacaine often results in motor paralysis and hemodynamic instability. Morphine appears to be the opioid of choice, and an epidural dose of 10% of the systemic dose is often used. Bupivacaine-induced adverse effects have been reported infrequently with bupivacaine doses less than 30-60 mg/d. Adjuvant drugs, such as clonidine and neostigmine, may further improve analgesia. Varied ranges of technical complication rates have been reported in the literature, with most being associated with epidural catheters. CONCLUSIONS A subcutaneous tunnelling and fixation of the catheter, bacterial filters, minimum changes of tubings, weekly exit site care, site protection, and monitoring for any signs of infection are suggested for advanced cancer patients. Areas still needing clarification include the optimum use of spinal adjuvants, the appropriate spinal morphine-bupivacaine ratio, methods to improve spinal opioid responsiveness, and long-term catheter management during home-care programs.