Background: Nusinersen is an antisense oligonucleotide approved in 2016 for the treatment of spinal muscular atrophy (SMA). Laboratory testing prior to each nusinersen administration is recommended to assess for thrombocytopenia, coagulopathy, and renal toxicity.
Objectives: We report our tertiary care center’s experience with intrathecal nusinersen administration in children and adults with SMA types I, II, and III.
Approach: We performed a retrospective chart review of all SMA patients receiving nusinersen between February 2017 and February 2019. We reviewed the pre-treatment platelet count, prothrombin time (PT), partial thromboplastin time (PTT), urine protein, and need for procedural sedation or fluoroscopy-guidance.
Results: 54 (26 male) patients ages 1 month- 56 years received 344 nusinersen doses. 20 had SMA type I, 12 had type II, and 22 had type III. There were no treatment-related serious adverse events, and no patients discontinued treatment. There were 153 lab abnormalities in 39 patients, most (136 (88.9%)) were mild. Only 17 (11.1%) were significantly abnormal, and none persisted on repeat testing or altered nusinersen treatment. 28 patients required either general anesthesia (62 doses) or anxiolysis with oral midazolam (88 doses, including 4 patients (13 doses) with SMA type I). None had respiratory complications. 1 patient had transient high lumbar cerebral spinal fluid opening pressure associated with general anesthesia. 6 patients (23 doses) required fluoroscopy-guidance, all without complications.
Conclusions: Intrathecal nusinersen is safe and well-tolerated, including in patients requiring the use of oral anxiolysis, general sedation, and fluoroscopy-guidance. Routine laboratory monitoring did not identify any persistent clinically significant findings in our cohort. A larger, multicenter study could better determine the utility of routine laboratory monitoring during nusinersen treatment.