In the present retrospective investigation, the long-term effects of continuous intrathecal
opioid therapy via
implantable infusion pump systems were examined in 120 patients with chronic, nonmalignant
pain syndromes. The follow-up period was 6 months to 5.7 years (mean 3.4 years +/- 1.3 standard error of the mean).
Deafferentation pain and
neuropathic pain showed the best long-term results, with 68% and 62%
pain reduction (visual analog scale), respectively. The mean
morphine dosage initially administered was 2.7 mg/day (range 0.3-12 mg/day); after an average of 3.4 years, it was 4.7 mg/day (range 0.3-12 mg/day). In a long-term observation of 28 patients who received intrathecal
morphine for longer than 4 years. 18 patients (64.3%) had a constant dosage history and 10 patients (35.7%) showed an increase in
morphine dosage to more than 6 mg/day 1 year after dosage determination. In seven cases, a tolerance developed: in four patients the tolerance was controlled by means of "
drug holidays"; but in three patients it was necessary to remove the pump systems. Explantation of the pump system occurred in 22 additional cases for other reasons. Throughout the follow-up period, 74.2% of the patients profited from the intrathecal
opiate therapy: the average
pain reduction after 6 months was 67.4% and, as of the last follow-up examination, it was 58.1%. Ninety-two percent of the patients were satisfied with the
therapy and 81% reported an improvement in their quality of life. The authors' 6-year experience with administration of intrathecal
opioid medications for nonmalignant
pain should encourage the use of this method in carefully selected patients.