Intrathecal granuloma formation as result of opioid delivery: Systematic literature review of case reports and analysis against a control group

Objective: To investigate the existence of an association between formation of catheter tip intrathecal inflammatory masses with opioid dose and/or concentration. Methods: A systematic review of catheter tip granulomas case reports and comparison with a control group was carried out. A boolean search was conducted in the electronic databases MEDLINE and EMBASE. The patients' data extracted from the case reports was tested for homogeneity with a control group. Subsequent analysis investigating the association of opioid dose, concentration and flow rate with the formation of catheter tip granulomas was performed. Results: Seventeen articles resulting in 24 patients with granulomata were included in the review. One patient in our department with granuloma formation was added to this group. Control group comprised 31 patients with an average follow-up of 68.3 ± 9.7 months. The groups were homogeneous considering the variables age, gender and duration of pain previous to implant. Morphine dose (r = 0.821, p < 0.001) and concentration (r = 0.650, p < 0.001) were significantly correlated with the development of catheter tip intrathecal masses. Conclusion: Opioid dose and concentration were significantly associated with the development of catheter tip granulomas. A correlation with opioid concentration was confirmed for the first time.