Several pieces of recently published research may aid clinicians in managing spinal muscular atrophy (SMA) across the life span. Review highlights of some of the studies below.
Early Treatment for Preterm Infants With SMA
SMA is being diagnosed earlier than ever before, even before symptoms arise. For preterm infants who do not yet demonstrate SMA symptoms but who possess 2 to 4 copies of the SMN2 gene, early intervention appears critical.
In this new piece in Muscle & Nerve, the authors argue that preterm infants should begin treatment at 37 weeks of gestational age, assuming other treatment criteria are met.1 They note, however, that the drug onasemnogene abeparvovec-xioi is not recommended by the US Food and Drug Administration (FDA) for this age group.
Hydrocephalus More Common in Patients With SMA
Since nusinersen began being administered to patients with SMA, hydrocephalus cases have been reported. Because the incidence of hydrocephalus in untreated SMA patients is currently unknown, it cannot be determined whether the disease or nusinersen may enhance hydrocephalus risk.
A new study that leveraged electronic health records from before the FDA approval of nusinersen was used to clarify whether SMA itself may increase the risk for hydrocephalus.2 The researchers identified 5354 cases of SMA and matched these cases with 5354 controls. Compared to only 9 hydrocephalus incidents in the non-SMA controls, the SMA group experienced 42 cases of hydrocephalus.
These results suggest that those with SMA may be approximately 4 times as likely to experience hydrocephalus than those without SMA. More research is needed to determine how nusinersen may impact this risk.
Expectations and Perception of Nusinersen Therapy
A new article in the European Journal of Neurology describes findings from an observational study of adult 5q SMA patients’ experience with nusinersen treatment.3 The study included 151 patients, whose median age was 36 years. During nusinersen treatment, there was a significant decrease in the median severity of symptoms.
While specific expectations differed based on their type of SMA, patients generally had a positive perception of the therapy. The convenience of drug administration was particularly important to their experience. These findings add to our understanding of what matters to SMA patients as they undergo treatment and can improve our ability to personalize treatment based on patient preferences.
Nusinersen Evaluated in Nonambulatory Adults With SMA
More data are accumulating to suggest that nusinersen is safe and well-tolerated in patients with SMA. In a new study published in Frontiers in Neurology, the safety, tolerability, and effectiveness of nusinersen treatment is evaluated specifically in 19 nonambulatory adults with 5q SMA.4
The results showed that nusinersen did not significantly affect laboratory results or vital signs and that most adverse events — including back pain, headache, urinary tract and upper respiratory infections, and cervical injection site pain — were not life-threatening. Hospitalization due to pneumonia occurred in 5 patients. While motor neurons appeared to stabilize with treatment, compound muscle action potential (CMPA) and motor unit size increased. Given that this study involved a small sample size, more research is needed before these results can be generalized.
1. Lee BH, Waldrop MA, Connolly AM, Ciafaloni E. Time is muscle: a recommendation for early treatment for preterm infants with spinal muscular atrophy. Muscle Nerve. Published online May 7, 2021. doi:10.1002/mus.27261
2. Viscidi E, Wang N, Juneja M, et al. The incidence of hydrocephalus among patients with and without spinal muscular atrophy (SMA): results from a US electronic health records study. Orphanet J Rare Dis. 2021;16(1):207. doi:10.1186/s13023-021-01822-4
3. Meyer T, Maier A, Uzelac Z, et al. Treatment expectations and perception of therapy in adult patients with spinal muscular atrophy receiving nusinersen. Eur J Neurol. Published online May 7, 2021. doi:10.1111/ene.149024. Elsheikh B, Severyn S, Zhao S, et al. Safety, tolerability, and effect of nusinersen in non-ambulatory adults with spinal muscular atrophy. Front Neurol. 2021;12. doi:10.3389/fneur.2021.650532