A prospective study of long-term intrathecal morphine in the management ofchronic nonmalignant pain

OBJECTIVE: To examine in a prospective manner the long-term safety and effi cacy of chronic intrathecal morphine in patients with severe, nonmalignant pain refractory to less invasive modalities. METHODS: Forty patients with severe, chronic nonmalignant pain poorly manag ed by systemic medications were identified as candidates for intraspinal tr ial of morphine. Thirty participants reported successful pain relief during trial and were implanted with an intraspinal delivery system. Standardized measures of pain and functional status were assessed before treatment was begun and at defined intervals during the subsequent 24 months. Intrathecal opioid use and pharmacological and device-related complications were also monitored. RESULTS: The participants had a mean age of 58 +/- 13 years and a mean pain duration of 8 +/- 9 years. Fifty-three percent of the study participants w ere women. Pain type was characterized as mixed neuropathic-nociceptive (15 of 30 patients, 50%), peripheral neuropathic (10 of 30 patients, 33%), dea fferentation (4 of 30 patients, 13%), or nociceptive (1 of 30 patients, 3%) . Forty-seven percent of the patients were diagnosed with failed back surge ry syndrome. Significant improvement over baseline levels of visual analog scale pain was measured at each follow-up examination after implant. Overal l, 50% (11 of 22 patients) of the population reported at least a 25% reduct ion in visual analog scale pain after 24 months of treatment. In addition, the McGill Pain Questionnaire, visual analog scale measures of functional i mprovement and pain coping, and several subscales of the Chronic Illness Pr oblem Inventory showed improvement throughout the follow-up period. Pharmac ological side effects were managed medically by morphine dose reduction, ad dition of bupivacaine, or replacement of morphine with hydromorphone. Devic e-related complications requiring repeat operations were experienced by 20% of the patients. CONCLUSION: Continuous intrathecal morphine can be a safe, effective therap y for the management of severe, nonmalignant pain among a carefully selecte d patient population and can result in long-term improvement in several are as of daily function.