P-018 Transforaminal intrathecal access for injection of nusinersen in children with spinal muscular atrophy

Abstract

Introduction Spinal muscular atrophy (SMA) is an autosomal-recessive inherited neuromuscular disorder that causes progressive loss of motor neurons in the anterior horn of the spinal cord, and is the leading genetic cause of infant mortality, affecting 1 in 10 000 live births. SMA causes diffuse symmetrical proximal muscle weakness, greater in the lower than upper limbs and absent or markedly decreased deep tendon reflexes. Clinically, SMA is divided into types 0 through 4 based on the age of onset and clinical course. Currently, the only approved treatment for all types of SMA is intrathecal Nusinersen (Spinraza®). The standard route to access the intrathecal space is through an interlaminar approach with the use of imaging guidance for patients who are obese or have complicated anatomy. Alternative routes such as transforaminal, C1/2 puncture or a caudal approach can also be considered based on the pathology and difficulty of routine interlaminar access. In older children, severe scoliosis develops secondary to neuromuscular weakness. Scoliosis in these children is typically progressive, which usually requires long segment surgical fusion with hardware and bone allografts for stabilization. In such patients, scoliosis itself and/or the surgical hardware preclude a standard interlaminar approach for gaining intra-thecal access and other routes such as fluoroscopy guided transforaminal approach should be considered instead. In this study, we report the safety and efficacy of transforaminal LP for the injection of Nusinersen in the subset of children who had extensive spinal fusion and/or scoliosis which precluded an interlaminar approach. Method This is a single-center study approved by our institutional review board. Retrospective chart reviews of all pediatric patients requiring fluoroscopically-guided intrathecal Nusinersen injections were performed. Demographic and procedural details and related complications were obtained from the electronic medical records. All transforaminal intrathecal injections were conducted under fluoroscopic guidance and patients were evaluated immediately and within two weeks follow up for complications. Results Between October 2017 and February 2018, we performed 36 Nusinersen injections in 12 children who were previously diagnosed with SMA. Fluoroscopic-guided transforaminal injections were successfully performed 19 times (52% of these injections) in 5 patients (3 male and 2 female) aged between 4 to 17 years (Mean=12 years). One patient had SMA type 1 and four had SMA type 2. The level and site of the Nusinersen injections are as follows: T12/L1 (Right=2), L1/L2 (Right=2), L2/L3 (Right=4, Left=7), L3/L4 (Right=4). General anesthesia was used in 15 procedures (79%) local anesthesia in 4 (21%). Four patients had chronic respiratory failure, three were BiPAP dependent, and three had osteoporosis. One patient had morbid obesity (BMI=33.8) but the rest had a BMI within the normal range (Mean=21.4). Complications such as post-LP headache, back pain, bleeding, radicular pain and/or paresthesias were not noted whether immediately after procedures or at 1–2 days and 2 weeks follow up. Conclusion Transforaminal lumbar puncture is a safe and effective method for delivering intrathecal Nusinersen in children with spinal muscular atrophy and complex spinal fusions that preclude the use of the standard interlaminar route. Disclosures T. Shokuhfar: None. P. Nazari: None. S. Ansari: None. M. Hurley: None. S. Azmi: None. N. Kuntz: 6; C; Biogen: membership on Medical advisory committee and honoraria for lectures. V. Rao: None. M. Potts: None. B. Jahromi: None. A. Shaibani: None.