“Reading the Palm”: Highly Sensitive Hand Grip and Finger Flexion Strength Is a Useful Outcome Measure in 5q Spinal Muscular Atrophy

Background/Purpose: Innovative RNA modifying and gene replacement therapies are currently revolutionizing the therapeutic landscape in 5q-associated spinal muscular atrophy (SMA). In order to provide appropriate recommendations for choice of treatment and therapy (dis-) continuation, objective outcome measures are needed. The purpose of this study was to determine whether maximum isometric voluntary grip and finger flexion strength (GFFS) is a prognostic and predictive outcome measure in children and adult patients with SMA.

Methods: In this prospective longitudinal study, we studied GFFS on 39 patients with SMA II and III (n = 16 children, mean age = 10 years; n = 23 adults, mean age = 38 years) using the highly sensitive Weber hand and finger dynamometer (HFD 200). GFFS, clinical (e.g., MRC sum score and FVC), and motor functions scores (Revised Upper Limb Module [RULM], Hammersmith Functional Motor Scale Expanded [HFMSE]) were assessed over a 12-month treatment period simultaneously with the nusinersen dosing scheme.

Results: GFFS was strongly associated with clinical and motor function scores, SMA type, walking ability as well as SMN2 copy number. Longitudinally, GFFS significantly increased in children and adults with SMA under nusinersen treatment.

Conclusion: GFFS measured with the HFD200 reflects SMA disease severity and increased during a 12-month treatment period with nusinersen. GFFS seems to be a promising and sensitive outcome measure for SMA.

Publication History

Article published online:
28 October 2021