EFFICACY AND TECHNICAL COMPLICATIONS OF LONG-TERM CONTINUOUS INTRASPINAL INFUSIONS OF OPIOID AND OR BUPIVACAINE IN REFRACTORY NONMALIGNANT PAIN - A COMPARISON BETWEEN THE EPIDURAL AND THE INTRATHECAL APPROACH WITH EXTERNALIZED OR IMPLANTED CATHETERS AND INFUSION PUMPS/

Objective: To compare efficacies, failure rates, and technical complic ation rates of intraspinal treatments in patients with ''refractory'' nonmalignant pain conditions in relation to the approach (epidural/int rathecal), the drug (opioid/opioid-bupivacaine or bupivacaine), and th e type of system used (externalized/internalized). In these comparison s, recent data from a companion paper (Nitescu et al., Clin J Pain 199 8; 14:17-28) were used as a reference to be compared with data from a literature review of different intraspinal treatment modalities in non malignant pain. Design: Prospective, cohort, nonrandomized, consecutiv e trial. Setting: Tertiary care center, institutional practice, hospit alized, and ambulatory care. Patients: Five groups according to treatm ent modality: (a) externalized, long-term intrathecal nylon catheters, connected to external, electronic infusion pumps (companion paper), n = 90; (b) internalized, long-term intrathecal catheters (Silastic(R)) connected to implanted SynchroMed(R) pumps, n = 330 (literature revie w); (d) externalized, long-term epidural catheters, n = 50 (literature review); (e) internalized, long-term epidural catheters, n = 111, con nected to implanted systems: Port-A-Cath(R) injection ports, n = 58; I nfusaid(R) pumps, n = 46, and SynchroMed(R) pumps, n = 7 (literature r eview). Interventions: In reviewing the literature, we found 21 studie s that reported on the intraspinal (epidural or intrathecal) administr ation of opioids with or without local anesthetics (usually bupivacain e). These studies were analyzed with respect to the rates of the varia bles satisfactory pain relief (efficacy), failures, and technical comp lications. A rate is the number of observations of a variable divided by the number of patients or the numbers of catheters or infusion syst ems, as logically indicated (e.g., the numbers of complications, such as epidural abscess and meningitis, were related to the number of pati ents and those of catheter occlusion or leakage to the number of the c atheters). The variables were expressed as the means of the rates of a variable from studies belonging to various treatment modalities: appr oach (epidural vs. intrathecal), duration (short vs. long term), drugs administered intraspinally (opioid vs. opioid and/or local anesthetic ), and type of infusion system (externalized vs. internalized). Furthe r, the sums of all observations of one variable in different studies w ith various treatment modalities were related to the corresponding sum s of the patients (alternatively, catheters or implanted devices). The proportions of these sums were tested for significance in relation to treatment modality. Main Outcome Measures: Comparative rates of succe ssful intraspinal treatment and its failures and complications. Result s: (a) The intrathecal approach, compared with the epidural approach, was associated with higher rates of satisfactory pain relief for both externalized (86/90, 95%: vs. 17/40, 42.5%, p < .0001) and internalize d (295/336, 89% vs. 33/56, 59%, p < .0001) catheters; higher rates of treatment failures with externalized epidural catheters than with inte rnalized intrathecal catheters (24/47, 51%, vs. 36/338, 11%, p < .0001 ); lower rates of treatment failures with internalized intrathecal cat heters than with internalized epidural catheters (36/338, 11% vs. 29/7 6, 38%, p < .0001); higher rates of system replacement with internaliz ed epidural catheters than with internalized intrathecal catheters (23 /32, 72% vs. 6/49, 12%, p < .0001); higher rates of system removal wit h internalized epidural catheters than with internalized intrathecal c atheters (22/49, 45% vs. 5/49, 10%; p < .001); higher rates of cathete r-related complications with epidural than with intrathecal catheters (dislodgement 13/126, similar to 10% vs. 6/150, 4%, p < .05; leakage 5 /51, similar to 10% vs. 1/116, 0.9%, p < .05; obstruction 21/75, 28% v s. 1/101, 1%, p < .0001). (b) The rates of satisfactory pain relief we re lower in the patients treated with epidural opioids (43/89, 48%) th an in those treated with intrathecal opioids (285/323, 88%, p < .0001) , intrathecal opioids and bupivacaine (96/103, 93%, p < .0001), and ep idural opioids and bupivacaine (7/7, 100%, p < .05). (c) Significantly higher rates of catheter dislodgement (8/124, similar to 6% vs. 1/152 , similar to 0.7%, p < .0001) and obstruction (21/75, 28% vs. 1/101, s imilar to 1%, p < .0001) and lower rates of accidental catheter withdr awal (0/441, 0% vs. 11/152, similar to 7%, p < .0001) were found with internalized than with externalized infusion systems. (d) Use of impla nted SynchroMed(R) pumps connected to implanted intrathecal Silastic(R ) catheters showed high rates of catheter (7-44%) and pump (6-44%) fai lures and no advantages over the externalized intrathecal catheters co nnected to electronic infusion pumps with regard to rates of pain reli ef, treatment failure, and system-related complications. Conclusions: (a) The intrathecal approach appeared to be superior to the epidural a pproach regarding satisfactory pain relief, treatment failure, and com plication rates. (b) Administration of epidural opioids was associated with lower rates of satisfactory pain relief than were intrathecal op ioids or opioids and bupivacaine, and epidural opioids and bupivacaine . (c) The use of totally implantable Synchromed(R) pumps seemed to be associated with high reported rates of technical failures.