Complications after Intrathecal Drug Delivery Due to the Underlying Malignancy in Two Patients with Intractable Cancer Pain

Intrathecal drug delivery is a mode of analgesic delivery that can be considered in those experiencing both refractory pain and excessive side effects from opioid and adjuvant analgesic use. Delivery of analgesic agents directly to the cerebral spinal fluid allows binding of the drug to receptors at the spinal level. Therefore, a reduced analgesic dosage can be afforded, resulting in reduction of drug side effects due to decreased systemic absorption. Drug delivery into the intrathecal space provides this benefit, yet it does not eliminate the possibility of drug side effects or risks of complications. Complications from this route of administration may be seen in the perioperative period or beyond, including infection, inflammatory mass, bleeding, and catheter or pump dysfunction, among others. This may manifest as new/worsening pain or as a neurologic deficit, such as a sensorimotor change and bladder/bowel dysfunction. Urgent evaluation with a detailed physical examination, device interrogation, and other workup including imaging is called for if symptoms suspicious for device-related problems arise. For the cancer pain patient, the underlying malignancy should also be considered as a potential cause for these new symptoms after intrathecal system implantation. We present 2 such cases of complications in the cancer pain patient after intrathecal drug delivery due to progression of the underlying malignant process rather than to surgical or device-related problems. The first patient had a history of metastatic osteosarcoma who, shortly after undergoing an intrathecal drug delivery trial with external pump, presented with new symptoms of both pain and neurologic changes. The second patient with a history of chondrosarcoma developed new symptoms of pain and sensorimotor change several days after intrathecal drug delivery system implantation. Key words: Intrathecal analgesia, intrathecal drug delivery, perioperative complications, cancer pain, malignant pain, pain pump