Effect of Scoliosis/Treatment on Pulmonary Function Relative to Stature in SMA

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Medicine and Health Sciences


Context: Children with SMA suffer from scoliosis, global weakness, and Thoracic Insufficiency (TIS). Normalized pulmonary function tests are inadequate when evaluating these patients for improvement in PFTs. Objective: Forced Vital Capacity (FVC) varies proportionately with thoracic height. Scoliosis severity affects this relationship: children w/Cobb relationship, while children w/Cobb >50 do not, and suffer from TIS. Spinal instrumentation (SI) partially restores this proportion. We evaluated whether FVC varies proportionately w/ stature, as represented by PIW, and if this relationship was affected by curve severity/treatment. Design: Retro Comparative Setting: Patients diagnosed with SMA at Boston Children’s Hospital with PFTs and x-rays. Methods: Bedside FVC and sitting spine X-ray in/out of TLSO and pre/post SI were evaluated serially. Moderate scoliosis was treated w/TLSO, whereas severe curves were treated by SI. Cobb, PIW and FVC @ treatment initiation were compared @ last f/u: 53 SMA pts. types: 1 (2%), 2 (53%), 3 (45%) were analyzed over 5 yrs. (SD 2.6; range 1.1-11.6 yrs). Results: For children with Cobb 50 there was no correlation (p=0.27); regardless of treatment. Linear mixed modeling for unbalanced groups and non-normal distributions comparing FVC/PIW for TLSO vs SI @ initiation vs last f/u, segregated by initial curve severity, indicate a difference in FVC/PIW for subjects >50° vs. < 50° (p=0.004) and for SI vs. TLSO (p=0.009). Conclusion: For SMA children with Cobb 50 there was no relationship, indicating PF disproportionate to stature = TIS. SI did not restore the proportional relationship between FVC and PIW.


Copyright 2018 all authors


Boston Children’s Hospital

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