A team of German researchers recently discovered that nusinersen, a disease-modifying therapy, can preserve bulbar function in patients with 5q-associated spinal muscular atrophy (SMA) types 2 and 3, according to a study published in Brain Sciences. They observed no changes (neither improvement nor decline) in the bulbar scores of those patients, which implied that nusinersen achieved a persevering effect on bulbar function.
“The results of this study aim to contribute to a standardized assessment of bulbar function in adult SMA patients, which may show therapeutic effects of gene-based therapies that are not evident from standard motor scores,” the authors of the study wrote.
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Motor function improvement is monitored using scales such as the Hammersmith Functional Motor Scale Expanded and the Revised Upper Limb Module. However, these scales evaluate trunk and extremity function and leave out bulbar function. Previous studies suggest that bulbar function declines in patients with SMA. The research team thus decided to evaluate bulbar function in SMA patients treated with nusinersen.
The researchers recruited 57 SMA patients at the Department of Neurology, University Medicine Essen, Germany, and collected data prospectively between July 2017 until May 2021. All 57 patients were molecularly confirmed 5q-SMA and had been on therapy for at least 6 months. A total of 22 among them had SMA type 2 or 3.
Bulbar function was assessed with bulbar function items from scales such as the Amyotrophic Lateral Sclerosis Functional Rating Scale Revised (ALSFRS-R) and the Sydney Swallow Questionnaire (SSQ). Data were collected during the patients’ visits for nusinersen injection at baseline (T0), as well as 6 months (T1) and 14 months (T2) after therapy.
The results showed no significant improvement in bulbar function using the ALSFRS-R between T0 and T1 and between T1 and T2. From T0 to T2, bulbar improvement was recorded in 5 patients, worsened in 2 patients, and unchanged in 6 patients. Using the SSQ, bulbar improvement was recorded in 6 patients between T0 and T2, while 6 patients experienced bulbar worsening during the same period.
In discussing the results of this study, the research team wrote, “Whether improvements in bulbar scores under nusinersen would show after a follow-up period longer than 14 months remains unclear.” However, in the period studied (up to 14 months), it is clear that a significant decline was not observed in SMA patients using nusinersen, showing that it has some therapeutic effect in patients with SMA.
Brakemeier S, Stolte B, Thimm A, et al. Assessment of bulbar function in adult patients with 5q-SMA type 2 and 3 under treatment with nusinersen. Brain Sci. Published online September 20, 2021. doi:10.3390/brainsci11091244