Indium-111 diethylene-triamine-pentaacetic acid scintigraphy in the evaluation of function and patency of baclofen intrathecal infusion systems

Abstract

Object Baclofen pump infusion systems are used for the treatment of patients with severe spasticity. When symptoms do not respond to infusion rate increases, the cause may be pump malfunction or catheter obstruction. The purpose of this investigation was to review the authors' experience with indium-111 diethylene-triamine-pentaacetic acid (In-111 DTPA) scintigraphy for evaluation of baclofen infusion system function and patency and to correlate scintigraphic findings with patient treatment and outcome to determine optimal methodology and diagnostic criteria. Methods Ten scintigraphic studies acquired in eight patients (five adults, three adolescents) were retrospectively reviewed. Imaging was routinely performed at 4, 24, 48, and 72 hours after injection of In-111 DTPA into the pump reservoir. The results of the studies were interpreted by two nuclear medicine physicians who had no knowledge of the patients' clinical history or outcome. The scintigraphic findings (for example, radiotracer detected in the basal cisterns, cervical or thoracolumbar regions, infusion catheter, and pump) were recorded and correlated with neuroimaging findings, patient history, treatment, and clinical response to therapy. Results In cases in which the basal cistern could be visualized at any time and those in which radiotracer was visualized in the thoracolumbar intrathecal region within 48 hours, the pump systems were functional and symptoms responded to an increase in infusion rate. One patient in whom activity was visualized in the thoracolumbar intrathecal region by 72 hours also experienced clinical improvement with a flow rate increase. Visualization of the pump alone or only the pump and the subcutaneous catheter was consistent with catheter obstruction or pump malfunction. Conclusion The use of In-111 DTPA scintigraphy of intrathecal baclofen infusion systems can play an important role in determining the functional status of these systems and guiding subsequent patient care.