A Comprehensive Institutional Overview of Intrathecal Nusinersen Injections for Spinal Muscular Atrophy

Abstract

Background: Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder resulting in progressive muscle weakness. In December 2016, the U.S. Food and Drug Administration approved the first ever treatment for SMA, a drug named nusinersen (Spinraza) which is administered intrathecally. However, many SMA patients have neuromuscular scoliosis and/or spinal instrumentation resulting in challenging intrathecal access. Therefore alternative routes must be considered in these complex patients. Methods: This study was reviewed and approved by our institution’s institutional review board. From March to December 2017, institutional SMA patients were referred for intrathecal nusinersen injections. In select patients with spinal hardware, spinal imaging was requested to facilitate pre-procedure planning. Standard equipment for intrathecal injections was utilized. All patients were followed-up by their referring neurologist. Results: A total of 104 intrathecal nusinersen injections were performed in 26 patients with 100% technical success. 60 procedures were performed without pre-procedural imaging and via standard interspinous technique. The remaining 44 procedures were performed in 11 complex (i.e. neuromuscular scoliosis and/or spinal instrumentation) patients requiring pre-procedural imaging for planning purposes. 19 of 44 complex procedures were performed via standard interspinous technique from L2 to S1. 22 of 44 complex procedures were performed using a neural-foraminal approach from L3 - L5. 3 of 44 complex procedures were performed via cervical puncture technique. There were no immediate or long-term complications but 1 short term complication of meningismus and back pain at the injection site. Conclusion: Although we achieved 100% technical success in intrathecal nusinersen administration, our practice habits evolved during the course of this study. Our early experience has led to the development of an algorithm to assist in promoting safe and effective nusinersen administration in children with Spinal Muscular Atrophy regardless of SMA type, abnormal spinal anatomies and complex spinal instrumentation.