Isotopic scintigraphy coupled to tomodensitometry: Interest in the diagnosis of baclofen pump dysfonction

Introduction.– Intrathecal baclofen (ITB) infusion is an established method for the treatment of diffuse and disabling spasticity. The most frequent technical problems are due to catheter/pump dysconnections and diagnosis of dysfunction may be difficult.Observation.– We report the case of a 53-years-old woman suffering from multiple sclerosis with spastic paraplegia treated with ITB pump. Spasticity remained uncontrolled despite a gradual increase of ITB dosage up to 850 μg/day. Tests with baclofen infusion by lumbar puncture (150 μg) refuted any resistance to this drug. Plain films found a distal catheter directed downward with a catheter tip at L5 level without apparent disconnection or failure. An Indium 111 DTPA scintigraphy coupled with a tomodensitometry was performed. It was found that the activity of the radioisotope was maximal next to the first sacral vertebra related with the atypical orientation of the intrathecal catheter distal extremity. No leakage of the product was revealed. Very low activity of the radioisotope was observed above the lumbar level. The catheter was then replaced at T7 level. One month later, spasticity was well controlled. Six months later, a second Indium111 DTPA scintigraphy confirmed a high activity of intrathecal radioisotope up to the basal cisterns.Discussion.– This observation emphasizes the importance of Indium111 DTPA scintigraphy coupled with a tomodensitometry in the etiologic diagnosis of uncontrolled spasticity in patients with ITB pump. Baclofen stagnation in the dural sac shown in these investigations is related with the orientation of the catheter.