Catheter-tip Granulomas Associated with Intrathecal Drug Delivery – A Two-Center Experience Identifying 13 Cases

Background: Intrathecal (IT) drug therapy with implanted pumps is an effective treatmentmodality for chronic pain and/or spasticity, especially after non-invasive treatment has failed.Long-term use of intrathecal opioids may cause formation of inflammatory masses at the tip ofintrathecal catheters, possibly leading to neurological deficits and/or catheter revision.Objective: We aimed to identify risk factors for catheter-tip granuloma (CG) formation.Study Design: Retrospective study.Setting: Tertiary Spine Centers in Germany and SwitzerlandMethods: We retrospectively reviewed data at 2 Swiss centers (Kantonsspital St. Gallen, SwissParaplegic Centre Nottwil) between 01/1994 and 10/2013. Collected data were age at operation,gender, smoking status, previous spinal operations, spinal level of catheter-tip, clinical symptoms,catheter testing with contrast agent, applied drugs, drug concentration, as well as cumulative dailydrug dosages.Results: Thirteen patients with a mean age of 52.6 years and CG formation after a mean of6.9 years of follow-up were identified and compared to 54 patients of similar age and length offollow-up (48.6 years, P = 0.535; follow-up 5.3 years, P = 0.236) without CG. In the analysis of riskfactors, catheter ending in the middle thoracic spine (Th4-8; 38.5 vs. 6.5%; P = 0.010), previousspinal surgery (75 vs. 41%; P = 0.051), and chronic pain as an underlying primary symptom for ITdrug therapy (100 vs. 56%, P = 0.003) were associated with CG formation. IT drug therapy forspasticity appeared to be much less associated with CG formation (0 vs. 44%, P = .0003). As thesymptomatology is closely related to the medical treatment applied, patients with CG were morelikely to be treated with IT morphine (77 vs. 20%; P < 0.001), and as tendency with IT clonidine(54 vs. 26%; P = 0.092) and IT bupivacaine (46 vs. 20%; P = 0.077). Average in-pump morphineconcentration (30.3 vs. 19.5 mg/mL; P = 0.05) as well as average daily dose of morphine (12.5 vs.6.2 mg/d; P = 0.037) were significantly higher in the CG group. Smoking could not be identifiedas risk factor for CG formation.Limitations: Limitations include the retrospective approach, the limited group size of granulomapatients, as well as missing data in the investigated patient groups.Conclusion: Our patient cohort with CG differed in some features, of which some like catheterlocalization, choice, dosage, and the concentration of drugs are potentially modifiable. Theseresults could contribute to the prevention of CG in the future.Key words: Intrathecal drug delivery, intrathecal cathether-tip granuloma, intrathecal cathethertip inflammatory masses, intrathecal morphine, drug pump complications