Nusinersen Administration in Spinal Muscular Atrophy Patients with Severe Scoliosis: Interlaminar Approaches at the Lumbar Level

Purpose: Spinal muscular atrophy (SMA) is a genetic progressive neuromuscular disorder, and nusinersen has shown to improve its symptoms. Scoliosis is a frequent symptom in patients with SMA and complicates the intrathecal injection of nusinersen. The aim of this study was to investigate the safety and effectiveness of fluoroscopy-guided intrathecal injections in patients with SMA with severe scoliosis. Methods: We retrospectively reviewed the medical records of 11 patients with SMA treated with nusinersen intrathecal injections at the Samsung Medical Center from 2018 to 2020. We assessed the type of SMA, genetic results, spine computed tomography or fluoroscopy findings, and adverse effects associated with the injection. Results: Of 11 patients with SMA, six were diagnosed with severe scoliosis, four of whom underwent an operation for scoliosis. The six patients with severe scoliosis started receiving the nusinersen injection at a median age of 15.7 years. A total of 25 injections were completely performed with the interlaminar approach (ILA) at the lumbar level under C-arm fluoroscopy guidance. No adverse effects other than mild headache occurred. In one patient who underwent the complete fusion operation for scoliosis, laminectomy was performed for the nusinersen injection, and 3 doses were administered intrathecally via the interlaminar route at the lumbar level. Conclusion: Fluoroscopy-guided ILA is a safe method for the intrathecal injection of nusinersen in patients with SMA with severe scoliosis. When defining the route, laminectomy might be necessary to open the window for the ILA route at the lumbar level.