Treatment with nusinersen (Spinraza®) may improve upper limb function in patients with impaired ambulation diagnosed with spinal muscular atrophy (SMA), according to a study recently published in the Orphanet Journal of Rare Diseases.
“In conclusion, our results demonstrate improvements or stabilization of disease progression in most nonambulant children with SMA type 2 or type 3 under nusinersen treatment,” the authors wrote.
This prospective study included 256 patients from 34 neuropediatric centers, whose data forms part of SMArtCARE, a registry specific for SMA. This study focused only on nonambulant individuals previously diagnosed with either SMA type 2 or 3. Patients were 2 to 12 years of age.
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All participants initiated treatment with nusinersen, and almost a third (32.4%) increased their scores on the Revised Upper Limb Module scale (RULM), while 24.6% improved their Hammersmith Functional Motor Scale Expanded (HFMSE) score to a clinically meaningful extent. Regardless, a decrease in both the RULM and HFMSE scores occurred in 1.2% and 4.3% of the cases, respectively.
A possible explanation for the differing results on each scale may be that scoliosis and contractures can affect the HFMSE results; hence, the RULM scale may be preferred for assessing improvement and disease progression in nonambulant patients, the authors noted.
Importantly, no patient lost a motor milestone, suggesting a decreased disease progression. Furthermore, 8.6% of the participants gained a new motor skill. These results are meaningful in the context of SMA type 2 since these patients often present with progressive muscle weakness, loss of muscular functions, and an overall decline in the assessment scales.
“Thus, a stabilization of disease status can already be considered as a positive response to treatment,” the authors wrote.
The findings also highlighted adverse events associated with nusinersen, including those related to lumbar puncture, respiratory tract infections, pyrexia, respiratory distress, headache, vomiting, and back pain.
Pechmann A, Behrens M, Dornbrack K, et al. Improved upper limb function in non-ambulant children with SMA type 2 and 3 during nusinersen treatment: a prospective 3-years SMArtCARE registry study. Orphanet J Rare Dis. Published online October 23, 2022. doi:10.1186/s13023-022-02547-8