Study Design: Case report. Patient Sample: A 42- year-old Caucasian male. Results: Catheter-tip granuloma formation is possible despite a normal catheter access study in patients with intrathecal (IT) infu- sion systems and its recurrence is possible after surgical excision. Increasing concentrations of hydromorphone from 50 mg/ml to 100 mg/ml without altering the daily dosage may have precipitated granuloma formation. Conclusions: In patients with previously implanted spinal catheters for intrathecal drug delivery, catheter access studies cannot be relied upon to rule out catheter-tip granulomas, which should be included in the differential diagnosis in patients with worsening clinical conditions or new onset neurologic symptoms. Caution should be exercised when increasing concentrations of intrathecal opioids while monitoring for signs or symptoms of intrathecal catheter- tip granuloma formation. Removal of previously implanted catheters and/or reductions in opioid concentrations may be necessary to prevent recurrent granuloma formations, which can occur quickly after surgical excision.