Clinical Trials in Spinal Muscular Atrophy: Protocol Development and Reliability of Quantitative Strength Assessment Method

Authors:
  • LBLisa Barker
    Lisa Barker
  • CSCindy Smith
    Cindy Smith
  • BPBetsy Perkins
    Betsy Perkins
  • KBKaren Burhans
    Karen Burhans
  • RNRhonda Newman
    Rhonda Newman
  • LZLaurie Zimmerman
    Laurie Zimmerman
  • JCJay Cook
    Jay Cook
  • BRBarry S. Russman
    Barry S. Russman
  • FSFrederick Samaha
    Frederick Samaha
  • SISusan Iannaccone
    Susan Iannaccone
  • CBC. Ralph Buncher
    C. Ralph Buncher
  • MWMichael White
    Michael White
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Abstract
We have developed a protocol to evaluate, prospectively, patients with spinal muscular atrophy (SMA) so that the natural course may be defined and treatment efficacy measured. A fixed myometry system with a sensitivity of 0.5 kgs. of force was used to eliminate the subjectivity experienced with manual muscle testing and handheld dynamometry. Thirteen patients were evaluated weekly for twelve weeks by the clinical evaluators (CEs). Intrarater reliability was established by demonstrating that repeated measurements by the same examiner were consistent. The CEs examined patients at each of the participating institutions on three separate occasions. Interrater reliability was demonstrated by showing that the strength evaluations made on the same subject by different evaluators did not differ significantly. The fixed myometry system was found to be a highly reliable method for evaluating very weak muscle groups in patients with SMA.