AbstractIntroductionThis retrospective study reports our tertiary care center's experience with intrathecal nusinersen administration in children and adults with spinal muscular atrophy (SMA).MethodsWe reviewed safety monitoring laboratory results and need for procedural sedation and fluoroscopy‐guidance in all SMA patients receiving nusinersen between February 2017 and March 2020.ResultsFifty‐eight patients ages 1 mo‐ 56 y received 494 nusinersen doses. There were 166 laboratory abnormalities in 45 patients. Most were either mild (145 [87.3%]) or were transient proteinuria (18 [10.8%]). None altered nusinersen treatment. Twenty‐eight patients required either general anesthesia (75 doses) or anxiolysis with oral midazolam (133 doses, including 6 patients [23 doses] with SMA type I). Eight patients with complicated spines (45 doses) required fluoroscopic guidance. One treatment‐related serious adverse event (emesis leading to intubation) occurred during general anesthesia. Two children had asymptomatic increased intracranial pressure. No patients discontinued treatment due to adverse events.DiscussionIntrathecal nusinersen is generally safe and well‐tolerated, including in patients requiring oral anxiolysis, general sedation, and fluoroscopic guidance. Frequent serial laboratory monitoring did not identify any persistent significantly abnormal findings or alter treatment.