[Continuous administration of opiates with implantable drug delivery systems in patients with intractable non-malignant pain.].

The use of implantable systems for intrathecal administration of opioids in chronic pain of non-malignant origin is a controversial subject. Opioid therapy is reserved mainly for pain patients with malignant disease and reduced life-expectancy. The main reasons for this restricted range of indications of chronic subarachnoid administration of opioids are fear of addiction and the build-up of tolerance. During July 1988 and April 1990 we treated 60 patients suffering from pain of non-malignant origin with continuous opioid infusion by implanted pumps. Wishing to find whether opiates can relieve deafferentation pain, we subdivided the different pain syndromes into three groups according to their pathophysiology: nociceptive, neurogenic/neuropathic, and deafferentation pain. After a follow-up period of 11.5+/-7.1 months 47 patients were evaluated. Pain intensity according to the visual analogue scale was reduced in a mean of 79.4% of the patients. Activity level and mood scores as pain-associated parameters were both significantly increased after therapy. Analysis of the McGill Pain Questionnaire reveals that the improved quality of life is attributable to a reduction of affective pain perception more than to sensory discrimination. The best results in terms of pain reduction (82.5%) were obtained in the group of patients with deafferentation pain. This is in contrast to reports in the literature. It seems that neuropathic and deafferentation pain syndroms are susceptible to intrathecal opioids. The initial daily average dose of morphine was 2.6 mg/day, increasing to 6.1 mg/day after 25 months without the development of major tachyphylaxis. the administration of intrathecal opioids by means of implantable systems is justified in carefully selected patients with chronic non-malignant pain. This method should be applied in preference to destructive neurosurgical treatments.