Isotopic scintigraphy combined with computed tomography: a useful method for investigating inefficiency of intrathecal baclofen

Intrathecal baclofen infusion is an established method for the treatment of generalized and disabling spasticity. The most frequent technical problems are due to catheter /pump disconnections, but diagnosis of dysfunction may be difficult. We report here the case of a 53-year-old woman with spastic paraplegia treated with intrathecal baclofen. Spasticity remained uncontrolled despite a gradual increase in baclofen dosage. On plain radiographs the distal end of the catheter was found to be pointing downwards with the catheter tip at level L5 and no apparent disconnection or failure. Indium111 diethylenetriamine penta-acetic acid (DTPA) scintigraphy combined with computed tomography revealed that the activity of the radioisotope was highest next to the first sacral vertebra and that there was no leakage. Radioisotope activity above the lumbar level was very low. The catheter tip was therefore repositioned to level T7. One month later, spasticity was well controlled and a second scintigraphy confirmed high activity of intrathecal radioisotope up to the basal cisterns. The combination of Indium111 DTPA scinti-graphy with computed tomography allows anatomical and functional investigation of intrathecal drug administration. In this case report this approach showed that the inefficiency of intrathecal baclofen was due to the caudal orientation of the catheter.