LB: Scoliosis Correction in Spinal Muscular Atrophy: The Influence of Genetic Severity, Function and Disease-Modifying Agents on Post-operative Outcomes


Clinical Management

Poster Number: T442


Jason Howard, MD, Nemours Children's Hospital, Alfred I. duPont Campus, Sadettin Ciftci, MD, Nemours Children's Hospital, Alfred I. duPont Campus, Wade Shrader, MD, Nemours Children's Hospital, Alfred I. duPont Campus, Mena Scavina, DO, Nemours Children's Hospital, Alfred I. duPont Campus, Robert Heinle, MD, Nemours Children's Hospital, Alfred I. duPont Campus, William Mackenzie, MD, Nemours Children's Hospital, Alfred I. duPont Campus

Background: Spinal muscular atrophy (SMA) is caused by abnormalities of the survival motor neuron (SMN) 1 gene, leading to a loss of spinal cord alpha motor neurons. Disease-modifying agents (DMA) targeting the involved genes (SMN1 and SMN2) have improved gross motor function, but impacts on post-operative outcomes after scoliosis correction remain unclear.

Objectives: The purpose of this study was to evaluate post-operative outcomes following scoliosis surgery, specifically analyzing the impact of functional level, genetic severity, and DMA use. We hypothesized that genetic severity by decreased SMN2 copy # would increase the risk of post-operative complications by Clavien-Dindo (CD) grading (1-2=less severe, 3-5=more severe), while DMA use would be protective.

Results: 74 patients (40% female) with SMA type I(21,28%), II(40,54%), III(11,15%), unknown (2,3%) met the inclusion criteria, with total post-operative follow-up duration 8.0±4.1 years. Surgery type was posterior spinal fusion for 53(72%) and growing rods for 21(28%), with mean age at surgery 12.0±2.4 and 6.2±2.9 years, respectively. Primary curve and pelvic obliquity correction was 44±20° (74±22° preop, p<0.001) and 11±9° (17±11° preop, p<0.001), respectively. DMA treatment was utilized preoperatively and post-operatively for 17(23%) and 57(77%) patients, mean duration 2.2±0.8 years and 3.8±1.3 years, respectively. SMN2 copy # was available for 31(42%) patients: 13(42%) <3, 18(58%) ≥3. Postoperative complication rates were not significantly influenced by SMA type or SMN2 copy number. DMA use before surgery was associated with: similar rates of postoperative complications but were less severe (6 vs 28% CD 3-5 grades, for DMA vs no DMA use, respectively, p=0.05), decreased days intubated (0.2 vs 1.6, p<0.0001), and decreased hospital length of stay (LOS, 4.6 vs 11.0 days, p=0.0001). Overall, %FVC decreased from preoperative to final follow-up (60.0% to 51.8%, p=0.002), unrelated to surgery type (p=0.98), DMA use (p=0.26), or SMN2 copy # (p=0.27).

Conclusions: Post-operative complications, though high in frequency overall, were typically less severe (CD 1-2) with preoperative DMA treatment. Pulmonary function was not improved after scoliosis surgery at final follow-up, nor was it affected by fusion vs growth friendly procedures, DMA treatment, or disease severity. Improvements in hospital LOS and days intubated postoperatively are potential benefits of preoperative DMA treatment.