Sleep disordered breathing in infants identified through newborn screening with spinal muscular atrophy.

BACKGROUND: Spinal muscular atrophy (SMA) is a genetic disorder that may result in neuromuscular weakness and respiratory insufficiency. Gene replacement therapy has changed the trajectory of this condition, but long-term outcomes related to sleep disordered breathing are not known. METHODS: This was a retrospective review of infants with SMA identified via newborn screening who subsequently received onasemnogene abeparvovec at the Hospital for Sick Children (Ontario, Canada). Polysomnograms were conducted at the time of confirmed diagnosis as well as regularly thereafter. RESULTS: Eleven children (4 female) were identified via newborn screen (7 with 2 copies of the SMN2 gene and 4 with 3 copies of the SMN2 gene) and received onasemnogene abeparvovec at a median age of 3.6 weeks. All eleven infants met criteria for sleep disordered breathing based on their first completed polysomnograms but improved over time. Three infants required respiratory technology, including a premature infant who was prescribed nocturnal supplemental oxygen therapy for central sleep apnea and two symptomatic infants with neuromuscular weakness who required nocturnal noninvasive ventilation. We did not find a correlation between motor scores and polysomnogram parameters. CONCLUSION: Children treated with onasemnogene abeparvovec have reduced sleep disordered breathing over time. Polysomnograms revealed abnormal parameters in all children, but the clinical significance of these findings was unclear for children who were asymptomatic for sleep disordered breathing or neuromuscular weakness. These results highlight the need to evaluate both motor scores and respiratory symptoms to ensure a holistic evaluation of clinical status.

Understanding caregiver experiences with disease-modifying therapies for spinal muscular atrophy: a qualitative study.

OBJECTIVE: Spinal muscular atrophy (SMA) is a neuromuscular disorder that manifests with motor deterioration and respiratory complications. The paradigm of care is shifting as disease-modifying therapies including nusinersen, onasemnogene abeparvovec and risdiplam alter the disease trajectory of SMA. The objective of this study was to explore caregivers' experiences with disease-modifying therapies for SMA. DESIGN: Qualitative study including semistructured interviews with caregivers of children with SMA who received disease-modifying therapies. Interviews were audio recorded, transcribed verbatim, coded and analysed using content analysis. SETTING: The Hospital for Sick Children (Toronto, Canada). RESULTS: Fifteen family caregivers of children with SMA type 1 (n=5), type 2 (n=5) and type 3 (n=5) participated. There were two emerging themes and several subthemes (in parentheses): (1) inequities in access to disease-modifying therapies (variable regulatory approvals, prohibitively expensive therapies and insufficient infrastructure) and (2) patient and family experience with disease-modifying therapies (decision making, hope, fear and uncertainty). CONCLUSION: The caregiver experience with SMA has been transformed by the advent of disease-modifying therapies. Consistent and predictable access to disease-modifying therapies is a major concern for caregivers of children with SMA but is influenced by regulatory approvals, funding and eligibility criteria that are heterogenous across jurisdictions. Many caregivers described going to great lengths to access therapies, highlighting issues related to justice, such as equity and access. This diverse population reflects contemporary patients and families with SMA; their broad experiences may inform the healthcare delivery of other emerging orphan drugs.

Scoliosis in Spinal Muscular Atrophy Type 1 in the Nusinersen Era.

Background and Objectives: The introduction of spinal muscular dystrophy (SMA)-modifying therapies, such as antisense oligonucleotide therapy, has changed the natural history of SMA. Most reports on treatment outcomes have focused on motor scores and respiratory function. The objective of this study is to document the development and progression of scoliosis in patients with SMA1 treated with nusinersen. Methods: A descriptive single-center study was conducted in patients with SMA1 who were treated with nusinersen before 6 months of age. Data were collected on patients who met criteria, including age at the first nusinersen dose, number of nusinersen doses, degree of scoliosis, respiratory parameters, feeding route, and motor scores at baseline and follow-up. The Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) was subanalyzed using axial (AxS) and appendicular motor (ApS) scores to evaluate a possible correlation between scoliosis and axial muscle strength. Results: From our cohort, 31 percent (11/35) of patients had a diagnosis of SMA1. Sixty-three percent (7/11) met the inclusion criteria. All patients (7/7) showed initial improvement in their CHOP-INTEND scores in correlation with improvement on the ApS. Despite this, most patients did not show improvement in the AxS. Subsequently, all patients developed scoliosis in the first year of life with Cobb angles that ranged between 18° and 60°. Furthermore, total CHOP-INTEND scores had dropped in 2 patients alongside the development of a Cobb angle of >40°. Discussion: Despite the significant improvement in functional motor assessment in patients with SMA1, there is a progression of significant scoliosis despite treatment. Subsequently, lack or minimal improvement on the axial CHOP-INTEND scores may predict worsening on the total motor scores.