Scintigraphic evaluation of intrathecal infusion systems: Selection of patients for surgical or medical management

Purpose: Continuous intrathecal medication through a surgically implanted infusion system is an established method for treating intractable spasticity or pain. To determine if imaging can guide surgical or medical management in patients with suspected infusion system malfunction, we reviewed our experience in evaluating the functional status of these systems with indium-111 DTPA scintigraphy. Methods: We retrospectively reviewed 23 indium-111 DTPA studies in 19 patients (7 female, 12 male; ages 20-83 years, average age 47 years). Indications included intractable spasticity or increasing pain. Infusion systems were classified scintigraphically as either functioning or malfunctioning; malfunctions were further classified as either mechanical or catheter-related. Imaging findings were correlated with subsequent clinical management. Results: Fifteen of 23 (65%) studies demonstrated functioning infusion systems; these patients were all treated medically. Eight of 23 (35%) studies demonstrated malfunctioning systems; 6 of 8 were subsequently treated surgically and 2 of 8 medically. Conclusion: Indium-111 DTPA scintigraphy can differentiate between functioning and malfunctioning infusion systems, guiding appropriate medical or surgical management.