Relief of continuous chronic pain by intraspinal narcotics infusion via an implanted reservoir
D. W. Coombs, R. L. Saunders, M. S. Gaylor, A. R. Block, T. Colton, R. Harbaugh, M. G. Pageau and W. Mroz
Ten patients with intractable pain (five cancer and five nonmalignant) were
treated with continuous intraspinal morphine delivered by an implanted
continuous infusion system. Both patient groups were evaluated and compared
using an identical battery of psychometric examinations administered before
and 12 weeks after therapy. The cancer-pain group reported significant
reduction in pain on serial visual pain analogue scales at 12 weeks
compared with no change in the nonmalignant-pain group reports despite a
much lower baseline report in the cancer group. Both groups of patients
reduced their oral narcotic requirement significantly during continuous
intraspinal morphine infusion. While the cancer patients took more oral
narcotic at baseline, at 12 weeks no difference existed in oral intake
between the two groups. Both groups required significant serial increases
in infused morphine, indicating that spinal opiate receptor tolerance
occurs. The results of this study confirm the sustained analgesic efficacy
reported earlier in cancer-related pain syndromes, thus supporting further
cautious expansion of this therapy within the cancer-related pain
population. In contrast, a poor response was seen in the nonmalignant-pain
group, consistent with the unsatisfactory responses to many potentially
analgetic approaches to chronic nonmalignant pain. We are thus discouraged
from further use of this therapy in the patient with chronic nonmalignant
pain.
