Does cardiorespiratory polygraphy have a role in non-ventilated children with SMA?

Objective: To assess the role of routine cardiorespiratory polygraphy (CRP) in managing Sleep Disordered Breathing in children with spinal muscular atrophy (SMA) not receiving ventilation. Methods: We reviewed the results of children with SMA who had baseline CRP during 48 months. Children receiving mask or tracheostomy ventilation at the time of the sleep study were excluded. Each CRP was scored by a physiologist in accordance with American Academy of Sleep Medicine guidelines and reported by a respiratory paediatrician. Results: Currently there are 132 SMA patients at our unit of which 108 (82%) were referred for a CRP. A total of 43 patients (29 female) were included (13 patients with SMA1, 27 with SMA2 and 3 with SMA3). Twenty-four patients were receiving nusinersen at the time of the study, 10 risdiplam, 6 gene therapy (including 1 on nusinersen), and 3 were not on disease-modifying treatment. We performed 88 studies (median age in SMA1 6 months, SMA2 10 years, SMA3 14 years). Eight patients (19%) were started on mask ventilation following CRP. The remaining patients were continued to have regular follow-up CRPs (n=21) or were discharged (n=8), with 4 re-referred. Of 8 patients initiated on ventilation, the reason for CRP was assessment before spinal surgery in 2, 4 having routine CRPs and 2 were new referrals. Two patients (5%) were initiated on mask ventilation outside of their routine CRPs for clinical reasons. Conclusion: CRP benefits children with SMA who are not on ventilation, as patients starting mask ventilation mostly did so after a sleep study (19%). In 5% of patients, the decision to start ventilation was made on a clinical basis. Larger studies are needed to further explore this.