SMA is a degenerative neuromuscular disorder caused by genetic defects in the SMN1 gene. Nusinersen and risdiplam act to increase systemic SMN protein concentrations by improving the efficiency of SMN2 gene transcription. These medications were originally studied in infant populations, and although they have been FDA approved for use in adults, few studies have examined their longitudinal effects on the adult population with SMA.

This single-center, retrospective observational study includes data from January 1, 2017 to August 31, 2024 on 9 patients aged 39-76 who were diagnosed with SMA Types 2 or 3 by genetic testing and who had been on nusinersen, risdiplam, or both. Data was obtained from yearly physical therapy evaluations preceding and during treatment and included objective and validated scales such as the Revised Upper Limb Module for SMA (RULM), the Hammersmith Functional Motor Scale Expanded for SMA (HFMSE), and the Six Minute Walk Test (6MWT). Subjective data on motor strength and patient-experienced improvements in functional status were also collected.

In the nusinersen group (n=6), 67% patients showed significant improvement on at least one of the respective scales (≥3 point change on Hammersmith, ≥2 point change on RULM, ≥30m change on 6MWT), and 33% showed no significant change in scores, indicating disease stability. In the risdiplam group (n=2), 50% showed improvement, and 50% showed stability. The single patient who was switched from nusinersen to risdiplam showed stability on both medications. No patients in either group saw a significant decrease on any of the scales. All 9 patients also reported subjective improvements in motor function.

Nusinersen and risdiplam lead to improvements or maintenance in functional status for adults with SMA, offering significant benefit.