Intrathecal local anaesthetics in the treatment of refractory non-malignant pain. With special reference to bupivacaine and ropivacaine

Abstract

Introduction: Non-malignant pain remains one of the most invalidating of all medical disorders. Intrathecally administered opioids to non-malignant pain have so far been disappointing and remains controversial and unclear. In an attempt to increase the analgetic effect of the intrathecal pain treatment, we have added, or replaced the opioid with, bupivacaine or ropivacaine in the treatment.Methods: Study I: To explore the possibility of obtaining pain relief, 90 patients with various refractory non-malignant pain conditions were treated with continuous intrathecal infusion of bupivacaine alone, or in combination with an opioid. Study II: A literature review of 21 studies, were made to compare efficacies, failure rates, and technical complications rates of intraspinal treatments. Study III: Intrathecal analgesia with bupivacaine, alone or in combination with an opioid, were given to 37 patients with refractory pain located in the extremities, to explore the potential of prophylaxis and treatment of phantom limb pain. Study IV: A prospective, cross-over, double-blind, randomized study with 12 patients to evaluate if ropivacaine have any advantages compared with bupivacaine in the intrathecal treatment of refractory pain was performed. Results: Study I: The intrathecal period ranged from 3 to 1,706 days, median 60 days. 95% of the patients obtained acceptable pain relief. In the long run, the treatment failed in 34%. Study II: The intrathecal approach was associated with higher rates of satisfactory pain relief. Higher rates of catheter complications was found with the internalized than with the externalized infusion systems. Study III: All patients, but one, experienced acceptable pain relief during the treatment. During the treatment opioids were reduced threefold, the analgesics/sedative consumption was reduced by 50%. Only 4 patients had no phantom limb pain after the termination of the treatment. Study IV: The daily doses of ropivacaine were 23% higher than for bupivacaine. No other significant difference were found between the two drugs.Conclusions: Intrathecal infusions of opioid and bupivacaine provided satisfactory to excellent pain relief in most of the patients. In the long-run, the treatment was satisfactory in 61 of the 90 patients. The intrathecal approach was associated with significantly higher rates of satisfactory pain relief and lower rates of catheter-related complications than with the epidural approach. Higher rates of catheter dysfunction were found with internalized than with externalized systems. Continuous intrathecal treatment with bupivacaine, alone or in combination with an opioid, relieved pre-existing phantom limb pain during the treatment, but did not prevent it after the termination of the treatment, and could not prevent the development of phantom limb pain, when used prophylactically. Ropivacaine does not present any advantages over bupivacaine when administered intrathecally for relief of refractory pain.