SMA is a degenerative disease of the second motor neuron. Four subtypes exist (from I to IV) depending on the onset of the paralysis and best motor function achieved by the patient. Patients now benefit from three treatment options: repeated intrathecal injections of antisense oligonucleotides (nusinersen or Spinraza®), a single injection of an intravenous gene therapy product (onasemnogene abeparvovec or Zolgensma®) or oral intake of a molecule acting on the alternative splicing of the SMN2 gene (risdiplam or Evrysdi®). While many, mostly convincing, clinical trials have involved children, there is still a lack of such evidence in adults with SMA. This has not prevented regulators from authorizing the use of these medications in this population, except for gene therapy.
In an article published in May 2021, nine German centers reported on a joint prospective study to evaluate expectations and perceptions of the effects of treatment in 151 adults treated with nusinersen, aged 15 to 69 years (median age 36). In this study, 60% of them had a type III SMA, 34% a type II and 7% a type I. From the analysis of several scales, function scale (such as the ALS-FRS-ex, which is not a scale specific to SMA) or of perception scale (type MYMOP2), the authors conclude that the expectations regarding an innovative therapy of this kind are very varied according to the type of SMA, its severity, its duration and age of the patient. Despite the diversity of these expectations, patients generally find the treatment beneficial for them.