Opioid-Related Side Effects and Complications After Intrathecal Morphine Trial or Pump Implantation

Objective: A few cases of post-surgical spine syndrome (PSSS) are resistant to standard treatment. Intrathecal morphine (ITM) therapy can be used to achieve improved pain control with fewer side effects compared to systemic analgesics alone. ITM-associated complications may be associated with the intrathecal catheter, implanted pump, device management, and the drugs themselves.Methods: Twenty-six patients with PSSS were retrospectively evaluated. All patients had visual analog scale (VAS) scores of 7 or higher, which continued for more than 6 months, and all received a single dose of the ITM trial. If the VAS score was reduced by 50%, and there were no side effects from the trial, ITM pump (ITMP) implantation was performed for continuous morphine injection to control pain. Of the 26 patients, 19 underwent only the ITM trial, and 7 in whom the VAS decreased by more than 50% after the trial further underwent ITMP implantation. Patients who underwent only the trial were observed for an average of 5.4 days (range: 3–14 days), and those who underwent ITMP implantation were observed for an average of 55.9 months (range: 15–123 months). The occurrence of side effects following ITM injection and complications related to the ITM trial or ITMP implantation were analyzed. Results: The most common complications were drug side effects (n=11), followed by procedural (n=1) and equipment (n=1) side effects. The most common symptoms were urinary difficulty (n=8) and pruritus (n=3). Serious complications included a large lumbosacral subdural hematoma, intradural fibrotic tissues at the lumbar puncture site, and urinary retention (n=1). A case of mid-catheter occlusion caused by precipitated morphine crystals and skin infection on an implantable pulse generator was also reported (n=1). In another case, skin necrosis was observed in the surgical area (n=1). Conclusion: The most common drug-related side effect is urination difficulty, and patients generally recover within a few days after the ITM trial. Complications, such as procedure-related subdural bleeding or IT catheter blockage, may also occur. A better understanding of IT drugs, equipment, and meticulous procedural techniques, can allow a reduction of complications.