Recurrent intrathecal catheter-tip granuloma formation on a replaced system delivering low dose/concentration fentanyl and bupivacaine: a case report

Intrathecal drug delivery (IDD) is a well-established treatment modality for refractory chronic pain. Intrathecal catheter-tip granuloma (ICTG) formation is a known possible complication of opiate IDD and is likely triggered by mast cell degranulation. The use of low concentration and dosage of opioids that do not induce mast cell degranulation has been advised to mitigate the risk of ICTG formation. A patient in their 50s with history of multiple lumbar spine surgeries and refractory low back pain who was treated with IDD developed an initial ICTG while receiving intrathecal hydromorphone and bupivacaine. The patient's catheter was thus replaced and repositioned. The pump was also replaced due to repeat motor stall, and the infusate was changed from hydromorphone with bupivacaine to low-dose fentanyl with bupivacaine. Five years later, the patient developed myelopathic symptoms, and on imaging a new mass believed to be an ICTG was detected at the new thoracic catheter tip location. The patient was placed on normal saline infusion for 4 months before system explant, with some improvement of symptoms. ICTG formation is uncommon but can be a devastating complication of IDD if not properly diagnosed in a timely fashion. Repeat ICTG has only been documented twice in the literature, and ICTG with low dose fentanyl in combination with bupivacaine has not been reported. Despite using regimens and techniques to reduce the risk of ICTG formation, one must judiciously surveil their patients for the dreaded ICTG complication.