Spinal Muscular Atrophy (SMA) is caused by a deficiency of the survival motor neuron (SMN) protein due to loss of SMN1 and inefficient compensation by SMN2. This genetic architecture has driven the development of precision therapeutics. Over the past decade, SMA management has progressed from supportive care to RNA-based splicing modulation and gene replacement therapy.

This review analyzes the evolution of three therapeutic waves in SMA management: antisense oligonucleotides (nusinersen) for SMN2 splicing correction; systemic small-molecule splicing modifiers (risdiplam) addressing SMA as a multisystem disorder; and gene replacement therapy (onasemnogene abeparvovec), including recent intrathecal formulations expanding patient eligibility.

Precision therapies have profoundly altered the disease trajectory, especially when administered presymptomatically. Nusinersen sustains splicing correction, risdiplam restores SMN across central and peripheral tissues, and gene replacement offers durable, one-time genetic correction. However, critical challenges persist regarding therapeutic durability, optimal treatment sequencing, systemic involvement, and long-term safety.

The evolution of SMA therapies has transformed neurogenetics. Clinical benchmarks have successfully shifted from reactive, symptomatic management to proactive, molecularly targeted precision medicine.

Spinal muscular atrophy (SMA) is primarily a motor neuron disorder, yet peripheral neuropathic features have been variably reported. This systematic review evaluates nerve conduction study (NCS) findings in genetically confirmed 5q-SMA and examines whether neurophysiology can function as a biomarker.

Following PRISMA 2020 guidelines and a PROSPERO-registered protocol, PubMed, Embase and Scopus were searched through November 2025. Original studies reporting NCS in SMN1-confirmed SMA were included. Data on neuropathy patterns, SMN1/SMN2 status and treatment exposure were extracted. Study quality was assessed using Joanna Briggs Institute tools.

Twenty-three studies including 395 patients were identified. NCS methodology was heterogeneous, and only 12 studies (52.2%) reported sufficient detail to allow formal classification of neuropathy type. Among these, axonal abnormalities involving motor, sensory or sensorimotor fibers were most frequently reported. Demyelinating features were rare and occurred only in a sensorimotor distribution, often in association with potential alternative or modifying factors. Most longitudinal and treatment-focused studies relied on amplitude-only protocols, limiting assessment of sensory and demyelinating involvement. Longitudinal neurophysiological follow-up was reported in 156 patients, predominantly using compound motor action potential/sensory nerve action potential (CMAP/SNAP) amplitude-only protocols; within these constraints, treated patients were more often stable or improved, while deterioration was rare and observed only in untreated cases.

Motor axonal neuropathy is the most consistently detectable neurophysiological abnormality in 5q-SMA, largely reflecting methodological constraints. Longitudinal NCS data, predominantly CMAP-based, may provide supportive information for monitoring treated patients, but standardized and comprehensive NCS protocols are required to define the full spectrum of peripheral nerve involvement.

To describe motor, respiratory and quality of life changes in a mixed cohort of adults with spinal muscular atrophy (SMA) from a single tertiary rehabilitation center in Canada and to report preliminary psychometric evidence of a nationally recommended core outcome set over 12 months.

This real-world, mixed-treatment cohort, exploratory, single-site, prospective observational study followed fifteen adults with SMA over 12 months. Participants completed the Spinal Muscular Atrophy Recommended Toolkit (SMART), which consists of eight outcome measures (OM) assessed at baseline and 12 months. Concurrent and predictive validity were assessed using Spearman’s Correlation Coefficient (SCC). Longitudinal change and sensitivity to change were evaluated using the Wilcoxon signed-rank test and standardized response mean.

Ten participants were receiving disease-modifying treatments. None of the OMs demonstrated statistically significant changes over 12 months. Respiratory and motor function measures are independently clustered into two clusters. Only the Children’s Hospital of Philadelphia – Adult Test of Neuromuscular Disorders (CHOP-ATEND) exhibited high sensitivity to change. Forced vital capacity (FVC) >2 L or peak cough flow (PCF) >200 L/min corresponds with ceiling effects of the Revised Upper Limb Module (RULM) and SMA Functional Rating Scale (SMAFRS).

This exploratory study identified two collinear clusters between SMART OMs, suggesting measurement redundancy. SMART OMs did not demonstrate significant changes over 12 months in this small mixed-treatment cohort. Developing new OMs that are valid, reliable and responsive, and optimizing OM selection will reduce clinic and patient burden, and improve clinical utility in a real-world setting.

The aim of this study is to assess the evolution of respiratory and feeding support in children with spinal muscular atrophy (SMA) type 1 after 24 months of nusinersen treatment.

Data on SMA type 1 children treated with nusinersen between 2017 and 2023 from the Canadian Neuromuscular Disease Registry were extracted. The cohort was divided into two groups based on age at treatment initiation: ≤2 years and >2 years. The primary outcome was the (i) time to death or needing full-time (≥16 hours/day) ventilation and (ii) time to needing feeding tube support. The secondary outcomes were differences in respiratory and feeding support requirements between the two groups at 24-month follow-up.

Thirty-two children were included, and the median age (range) for treatment initiation was 3.2 months (0.8– 13.1) in children who initiated treatment at ≤2 years and 51.2 (28.7–183.8) in those who initiated at >2 years of age. The median age of death or full-time ventilation was 8.6 months (6–22.4) and 10.5 months (4–24) for the two groups, respectively. The median age for initiation of feeding support was 5.1 (1.7–26.4) and 14.5 months (3.9–130.6), respectively. At 24 months (n = 23), there were no significant differences between the need for respiratory or feeding tube support between the two treatment groups.

Most children with SMA type 1 treated with nusinersen across Canada have continued need for respiratory and feeding support over time when initiated after symptom onset.

Spinal muscular atrophy (SMA) is a progressive genetic disorder characterized by muscle weakness ultimately leading to pulmonary impairments that can be fatal. The recent approval of nusinersen, a disease-modifying therapy, substantially changed the prognosis for patients, particularly in children. However, real-world evidence about its long-term effectiveness in adults remains limited. This study aimed to document longitudinal data on motor function, pulmonary function and patient-reported outcome measures of Canadian adults with SMA type 2 and 3 treated with nusinersen.

Outcomes from 17 patients were collected at the Institut de réadaptation en déficience physique de Québec during routine clinical visits over 36 months post nusinersen treatment, using the Hammersmith Functional Motor Scale Expanded for SMA (HFMSE), Revised Upper Limb Module (RULM), 6-Minute Walk Test (6MWT), Children’s Hospital of Philadelphia Adult Test of Neuromuscular Disorders (CHOP-ATEND), SMA functional rating scale (SMAFRS), pulmonary function testing and subjective changes reported by patients.

After 36 months, 9 patients showed motor function improvement. Changes beyond the minimal clinically important difference were seen for four patients on the HFMSE, four patients on the RULM and five patients on the 6MWT. Pulmonary function remained stable for most subjects. Subjective positive changes were reported in 88% of patients and five patients showed improvement in the SMAFRS.

This real-world study demonstrates the positive effects of nusinersen in adults with SMA types 2 and 3. Although stabilizing the patient’s condition is considered therapeutic success, this study shows an improvement in motor function and subjective gains in several patients.

Spinal muscular atrophy (SMA) is a leading genetic cause of infant death and represents a significant burden of care. An improved understanding of the epidemiology of SMA in Canada may help inform strategies to improve the standard of care for individuals living with SMA.

We employed a multisource approach to estimate the minimal incidence and prevalence of 5q SMA and to gain greater insight into recent clinical practices and treatment trends for the Canadian SMA population. Data sources included the Canadian Paediatric Surveillance Program (CPSP), Canadian Neuromuscular Disease Registry (CNDR), and molecular genetics laboratories in Canada.

The estimated annual minimum incidence of 5q SMA was 4.38, 3.44, and 7.99 cases per 100,000 live births in 2020 and 2021, based on CPSP, CNDR, and molecular genetics laboratories data, respectively, representing approximately 1 in 21,472 births (range 12,516–29,070) in Canada. SMA prevalence was estimated to be 0.85 per 100,000 persons aged 0–79 years. Delay in diagnosis exists across all SMA subtypes. Most common presenting symptoms were delayed milestones, hypotonia, and muscle weakness. Nusinersen was the most common disease-modifying treatment received. Most patients utilized multidisciplinary clinics for management of SMA.

This study provides data on the annual minimum incidence of pediatric 5q SMA in Canada. Recent therapeutic advances and newborn screening have the potential to drastically alter the natural history of SMA. Findings underline the importance of ongoing surveillance of the epidemiology and long-term health outcomes of SMA in the Canadian population.

Newborn screening (NBS) identifies infants with severe, early-onset diseases, enabling early diagnosis and treatment. In Canada, decisions regarding disease inclusion in NBS programs occur at the provincial level, which leads to variability in patient care. We aimed to determine whether important differences exist in NBS programs across provinces and territories. Given that spinal muscular atrophy (SMA) is the most recent disease added to NBS programs, we hypothesized that its inclusion would show interprovincial variability and be more likely in provinces already screening for a greater number of diseases.

We conducted a cross-sectional survey of all NBS labs in Canada to understand: 1) what conditions were included in their program; 2) what genetic-based testing was performed and; 3) if SMA was included.

All NBS programs (N = 8) responded to this survey by June 2022. There was a 2.5-fold difference in the number of conditions screened (N = 14 vs N = 36) and a 9-fold difference in the number of conditions screened by gene-based testing. Only nine conditions were common to all provincial NBS programs. NBS for SMA was performed in four provinces at the time of our survey, with BC recently becoming the fifth province to add SMA to their NBS on October 1, 2022. Currently, 72% of Canadian newborns are screened for SMA at birth.

Although healthcare in Canada is universal, its decentralization gives rise to regional differences in NBS programs which creates inequity in the treatment, care, and potential outcomes of affected children across provincial jurisdictions.

Spinal muscular atrophy (SMA) is characterized by the progressive loss of motor neurons causing muscle atrophy and weakness. Nusinersen, the first effective SMA therapy was approved by Health Canada in June 2017 and has been added to the provincial formulary of all but one Canadian province. Access to this effective therapy has triggered the inclusion of SMA in an increasing number of Newborn Screening (NBS) programs. However, the range of disease-modifying SMN2 gene copy numbers encountered in survival motor neuron 1 (SMN1)-null individuals means that neither screen-positive definition nor resulting treatment decisions can be determined by SMN1 genotype alone. We outline an approach to this challenge, one that specifically addresses the case of SMA newborns with four copies of SMN2.

To develop a standardized post-referral evaluation pathway for babies with a positive SMA NBS screen result.

An SMA NBS pilot trial in Ontario using first-tier MassARRAY and second-tier multi-ligand probe amplification (MLPA) was launched in January 2020. Prior to this, Ontario pediatric neuromuscular disease and NBS experts met to review the evidence regarding the diagnosis and treatment of children with SMA as it pertained to NBS. A post-referral evaluation algorithm was developed, outlining timelines for patient retrieval and management.

Ontario’s pilot NBS program has created a standardized path to facilitate early diagnosis of SMA and initiation of treatment. The goal is to provide timely access to those SMA infants in need of therapy to optimize motor function and prolong survival.

Spinal muscular atrophy (SMA) is a devastating rare disease that affects individuals regardless of ethnicity, gender, and age. The first-approved disease-modifying therapy for SMA, nusinursen, was approved by Health Canada, as well as by American and European regulatory agencies following positive clinical trial outcomes. The trials were conducted in a narrow pediatric population defined by age, severity, and genotype. Broad approval of therapy necessitates close follow-up of potential rare adverse events and effectiveness in the larger real-world population.

The Canadian Neuromuscular Disease Registry (CNDR) undertook an iterative multi-stakeholder process to expand the existing SMA dataset to capture items relevant to patient outcomes in a post-marketing environment. The CNDR SMA expanded registry is a longitudinal, prospective, observational study of patients with SMA in Canada designed to evaluate the safety and effectiveness of novel therapies and provide practical information unattainable in trials.

The consensus expanded dataset includes items that address therapy effectiveness and safety and is collected in a multicenter, prospective, observational study, including SMA patients regardless of therapeutic status. The expanded dataset is aligned with global datasets to facilitate collaboration. Additionally, consensus dataset development aimed to standardize appropriate outcome measures across the network and broader Canadian community. Prospective outcome studies, data use, and analyses are independent of the funding partner.

Prospective outcome data collected will provide results on safety and effectiveness in a post-therapy approval era. These data are essential to inform improvements in care and access to therapy for all SMA patients.

Our aim was to describe the clinical evolution and needs of children with spinal muscular atrophy type I treated in a domiciliary palliative care program.

We undertook a retrospective chart review of nine consecutive patients. Descriptions of the clinical and demographic profile of children with spinal muscular atrophy (SMA) type I were referred to a pediatric palliative care team (PPCT).

Six males and three females were admitted to the PPCT, all before six months of age, except for one afflicted with SMA type I with respiratory distress. The median time of attention was 57 days (range 1–150). The domiciliary attention mainly consisted of respiratory care. The patient with SMA type I with respiratory distress required domiciliary mechanical ventilation by tracheotomy. In all cases, a nasogastric tube (NT) was indicated. As end-of-life care, eight required morphine to manage the dyspnea, four received it only by enteral (oral or NT) administration, and four received it first by enteral administration with continuous subcutaneous infusion (CSI) later. Three of the four patients with CSI also received benzodiazepines. While they were attended by the PPCT, none required hospital admission. All the patients died at home except for the one attended to for just one day.

Domiciliary care for these patients is possible. The respiratory morbidity and its management are the main issues. Application of an NT is useful to maintain nutritional balance. Morphine administration is necessary to manage the dyspnea. Palliative sedation is not always necessary.