Exploring functional strength changes during nusinersen treatment in symptomatic children with SMA types 2 and 3.

The Hammersmith Functional Motor Scale-Expanded (HFMSE) is a validated outcome measure for monitoring changes in functional strength in patients with spinal muscular atrophy (SMA). The objective of this study was to explore changes in HFMSE item-scores in children with SMA types 2 and 3a treated with nusinersen over a period of six to twenty months. We stratified patients according to motor ability (sitting and walking), and calculated numbers and percentages for each specific improvement (positive score change) or decrease (negative score change) for the total group and each subgroup and calculated frequency distributions of specific score changes. Ninety-one percent of the children showed improvement in at least 1 item, twenty-eight percent showed a score decrease in 1 or more items. In the first six to twenty months of nusinersen treatment motor function change was characterized by the acquisition of the ability to perform specific tasks with compensation strategies (score changes from 0 to 1). Children with the ability to sit were most likely to improve in items that assess rolling, whilst children with the ability to walk most likely improved in items that assess half-kneeling. The ability most frequently lost was hip flexion in supine position.
Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Danny R. van der Woude, his employer receives fees for SMA-related consultancy activities. Renske I Wadman, Research grants from Prinses Beatrix Spierfonds and Stichting Spieren voor Spieren, both non-profit foundations. Her employer receives fees for SMA-related consultancy activities. Fay-Lynn Asselman, her employer receives fees for SMA-related consultancy activities. Marja A.G.C. Schoenmakers, no conflicts of interest. Inge Cuppen, her employer receives fees for SMA-related consultancy activities. W Ludo van der Pol, Research grants from Prinses Beatrix Spierfonds and Stichting Spieren voor Spieren, both non-profit foundations. His-employer receives fees for SMA-related consultancy activities. Bart Bartels, Research grants from Prinses Beatrix Spierfonds, Stichting Spieren voor Spieren and Piet Poortmanfonds, all non-profit foundations. His-employer receives fees for SMA-related consultancy activities.
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