Intrathecal baclofen in multiple sclerosis and spinal cord injury: complications and long-term dosage evolution

Abstract

Objective: To investigate the long-term dosage evolution and complication rate of intrathecal baclofen use in multiple sclerosis and spinal cord injury patients, based on a large population with a long follow-up. Design: Retrospective data analysis Setting: Academic hospital Subjects: Patients with multiple sclerosis (n = 81) or spinal cord injury (n = 49) having an intrathecal baclofen pump implanted at the University Hospitals Leuven between 1988 and 2009. Intervention: Medical records review of included patients in August 2010. Main measures: Complications linked to intrathecal baclofen therapy. Daily baclofen dosage after 3 and 6 months, and yearly thereafter. Data on dosage evolution were analysed using a mixed-effect linear model. Results: In 130 patients with a mean follow-up of 63 months, comprising 797 pump years, 104 complications were recorded. This corresponds to a complication rate of 0.011 per month, equally divided among both groups. Seventy-eight of these complications were catheter related. The mean dosage of baclofen stabilizes two years after implantation at 323 µg/day in the multiple sclerosis population. In spinal cord injury patients the daily dose only stabilizes after five years at a significantly higher dosage (504 µg/day). No significant increase in dosage is seen in the long term. Conclusions: In multiple sclerosis and spinal cord injury patients, intrathecal baclofen therapy has a complication rate of 1% per month. Complications are mainly due to catheter-related problems (74%). The intrathecal baclofen dosage stabilizes in the long term, indicating that long-term tolerance, defined as progressive diminution of the susceptibility to the effects of a drug, is not present.