Case report: Technical risk mitigation and management strategies of semi-implantable intrathecal drug delivery systems for advanced cancer pain: a case-based study

Objective: This study investigated the clinical efficacy, technical risks, and management strategies of the semi-implantable intrathecal drug delivery system (IDDS) as a "fourth-step" analgesic regimen for refractory advanced cancer pain. Methods: We retrospectively analyzed three representative cases of patients with advanced cancer pain who underwent semi-implantable IDDS implantation under fluoroscopic guidance in a digital subtraction angiography (DSA) suite.The study was approved by the Institutional Review Board (IRB), and all patients provided written informed consent. Analgesic efficacy was assessed using the Visual Analog Scale (VAS) score. Technical challenges-including placement verification without cerebrospinal fluid (CSF) backflow, mechanical failures, and opioid dependency-were evaluated to develop standardized management protocols. Results: Significant analgesia was achieved in all cases. Preoperative VAS scores (8-10) decreased to 0-4 within 24 hours and stabilized at 0-1 after 72 hours. Specific technical risks were successfully mitigated through individualized strategies. Placement verification: In a cachectic patient (Case 1) with an iodine contrast allergy and absent CSF backflow, a "morphine test dose" (0.1 mg bolus) was utilized as functional confirmation of subarachnoid placement, justified by the rapid 10-minute analgesic onset. Mechanical issues: Repeated occlusion alarms in Case 2, caused by pressure sensitivity at the device's minimum flow rate (0.1 mL/h), were resolved by diluting the drug concentration to increase the basal flow rate and implementing a "U-shaped" redundant catheter loop at the port site. Opioid withdrawal: Case 3 developed acute psychological withdrawal symptoms (COWS score: 14) following the rapid reduction of high-dose systemic opioids. This was managed through a multidisciplinary cross-titration protocol involving oral oxycodone and cognitive behavioral therapy. No infectious complications occurred during the follow-up period (up to 8 weeks). Conclusion: The semi-implantable IDDS serves as a crucial, cost-effective palliative option for patients with advanced cancer pain and a life expectancy of 3-6 months. While its externalized design introduces technical risks, these can be effectively managed through high-resolution fluoroscopy-guided placement, flow-rate optimization, and multidisciplinary support. Standardized troubleshooting algorithms and strict patient stratification are essential to achieve the goal of "pain-free survival."