New onset lumbar radicular pain after implantation of an intrathecal drug delivery system: imaging catheter migration.

BACKGROUND AND OBJECTIVES

Implanted delivery systems for intrathecal drug administration have become more commonplace in the management of refractory cancer and nonmalignant pain. Complications may be related to drug side effects or to technical problems possibly involving the pump and/or catheter. The occurrence of postimplantation, new onset, lumbar radicular pain warrants careful clinical and radiographic examination. We suggest a paradigm for imaging of potential intervertebral foraminal catheter migration.

CASE REPORT

New onset, intractable, lumbar radicular pain occurred 3 months after implantation of a one-piece catheter into the lumbar cistern. Magnetic resonance imaging of the lumbar spine showed no granuloma but rather a contrast-enhancing lesion at the right L4-L5 intervertebral foramen. Subsequent computed tomography revealed migration of the catheter into the intervertebral foramen. Surgical repositioning of the catheter resulted in resolution of the symptoms.

CONCLUSION

Patients with implanted drug delivery systems with positioning of the catheter tip into the lumbar cistern may develop new onset lumbar radicular pain as a result of catheter migration into an intervertebral foramen. Magnetic resonance imaging (MRI) is suggested as the initial imaging study to survey the spine and to evaluate for granuloma formation. Reimaging with computed tomography is essential to follow the course of the catheter and to delineate distal catheter tip location. It is suggested that positioning of the distal catheter tip at a location midway between the superior and inferior articular surfaces of the facet joint may minimize this complication.