Neurophysiological Characteristics in Type II and Type III 5q Spinal Muscular Atrophy Patients: Impact of Nusinersen Treatment

Abstract

Objective

This study aimed to observe the neurophysiological characteristics of type II and type III 5q spinal muscular atrophy (SMA) patients and the changes in peripheral motor nerve electrophysiology after Nusinersen treatment, as well as the influencing factors.

Methods

This single-center retrospective case–control study collected clinical data and peripheral motor nerve CMAP parameters from 42 5qSMA patients and 42 healthy controls at the Second Affiliated Hospital of Xi’an Jiaotong University (January 2021 to December 2022). It evaluated changes in motor function and CMAP amplitude before and after Nusinersen treatment.

Results

Our investigation encompassed all symptomatic and genetically confirmed SMA patients, consisting of 32 type II and 10 type III cases, with a median age of 57 months (29.5 to 96 months). Comparative analysis with healthy controls revealed substantial reductions in CMAP amplitudes across various nerves in both type II and type III patients. Despite the administration of Nusinersen treatment for 6 or 14 months to the entire cohort, discernible alterations in motor nerve amplitudes were not observed, except for a significant improvement in younger patients (≤36 months) at the 14-month mark. Further scrutiny within the type II subgroup unveiled that individuals with a disease duration ≤12 months experienced a noteworthy upswing in femoral nerve amplitude, a statistically significant difference when compared to those with >12 months of disease duration.

Conclusion

Motor nerve amplitudes were significantly decreased in type II and type III 5q SMA patients compared to healthy controls. Nusinersen treatment showed better improvement in motor nerve amplitudes in younger age groups and those with shorter disease duration, indicating a treatment-time dependence.

Keywords:

• 5q spinal muscular atrophy
• neurophysiology
• peripheral motor nerve
• Nusinersen

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.

Additional information

Funding

This study was funded by Key R&D Plan of Shaanxi Province (No. 2021SF-087).