Continuous intrathecal morphine treatment for chronic pain of nonmalignantetiology: Long-term benefits and efficacy

BACKGROUND To analyze, prospectively, the long-term effects of continuous i ntrathecal morphine infusion therapy in 16 patients with chronic nonmaligna nt pain syndromes. METHODS Twenty-five patients with severe, chronic, nonmalignant pain that h ad proven refractory to conservative management were considered candidates for trial of intrathecal spinal morphine. Sixteen patients achieved more th an 50% pain relief after a trial period of intrathecal morphine infusion. T hey were implanted with fully implantable and programmable pumps through wh ich morphine was delivered intrathecally on a continuous basis. These patie nts were followed prospectively and underwent careful evaluation of their f unctional and mental status, and pain intensity measurements using standard ized techniques before treatment and every 6 months thereafter in the follo w-up period. The follow-up period ranged from 13 months to 49 months (mean 29.14 months +/- 12.44 months) for the patients who had implanted morphine pumps. RESULTS The mean morphine dosage initially administered was 1.11 mg/day (ra nge 0.2-6.5 mg/day); after 6 months, it was 3.1 mg/day (range 0.4-8.75 mg/d ay). In long-term observation, no patient had a constant dosage history. Th e patients who received intrathecal morphine for longer than 2 years all sh owed an increase in morphine dosage to more than 10 mg/day. The best long-t erm results were seen with deafferentation pain and mixed pain, with 75% an d 61% pain reduction (visual analog scale), respectively. Nociceptive pain patients had best pain relief initially (78% pain reduction) but it tended to decrease over the follow-up period to 57% pain reduction at final follow -up. The average pain reduction for all groups after 6 months was 67.5% and at last follow-up, it was 57.5%. Ten patients were satisfied with the deli very system and eleven reported improvement in their quality of life. In tw o patients, morphine was not able to adequately control the pain without pr oducing undesirable side effects requiring the addition of clonidine to the ir infusion medication. In this series, 12 patients were considered success es and 4 patients were considered failures. In two patients, the intratheca l opioid therapy was unable to produce satisfactory pain relief and in the other two patients the pumps had to be explanted because of intolerable sid e effects. CONCLUSIONS In our experience, the administration of intrathecal opioid med ications for nonmalignant pain is justified in carefully selected patients. (C) 2001 by Elsevier Science Inc.