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P9 Pseudo-obstructive sleep disordered breathing – definition and use as disease severity marker in spinal muscular atrophy
  1. Federica Trucco1,2,3,
  2. Sakina Dastagir1 and
  3. Hui-Leng Tan1
  1. 1Department Paediatric Respiratory medicine, Royal Brompton Hospital, London, UK, London, UK
  2. 2Dubowitz Neuromuscular Centre, UCL Institute of Child Health and Great Ormond Street Hospital, London, UK
  3. 3Department of Neurorehabilitation, University of Milan, Milan, Italy


Introduction Obstructive sleep disordered breathing (SDB) is prevalent in patients with Spinal Muscular Atrophy (SMA) and possibly reduced by disease modifying treatment (DMT) such as nusinersen.

We hypothesized that some obstructive events may in fact be pseudo-obstructive, reflecting the imbalance of chest wall weakness with preserved diaphragmatic function, rather than true upper airway obstruction. If confirmed, these events could represent SMA-specific outcome measures.

We aimed to report on the peculiar pattern observed in cardiorespiratory sleep studies (CR) in paediatric SMA patients resembling obstructive SDB. We defined pseudo-obstructive SDB and assessed its changes throughout disease progression.

Methods Retrospective review of 18 CR of 6 SMA2 patients naïve from DMT across 3 timepoints (first study, one-year follow-up, latest study).

Results At first study patients aged 3 to 13 years. The last assessment was 3 to 6 years after the first study. At first CR 4 patients were self-ventilating in room air; 1 of them was established on non-invasive ventilation (NIV) after the 1-year study. Two patients were on NIV since first study (table 1).

The observed features of pseudo-obstructive SDB included a.paradoxical breathing before, after, and throughout respiratory event, b.the absence of increased respiratory rate during the event, c.the absence of compensatory breath after the event with a return to baseline breathing (figure 1).

The abdominal contribution to the paradox was more prominent in presumed REM sleep confirming the physiological REM-related chest wall atonia.

Pseudo-obstructive events were progressively longer and more prevalent over time. The derived pseudo-obstructive AHI increased at each timepoint in all patients self-ventilating, whilst it reduced after NIV establishment or after adjusting NIV pressure support.

Abstract P9 Table 1

Study population and changes in pseudo-obstructive sleep disordered breathing across subsequent assessments

Discussion Pseudo-obstructive SDB is prevalent in SMA2. Its number and duration progress along with the disease and is treatable with NIV. Prospective studies on broader SMA cohorts are planned.1


  1. Bertran K, et al. Sleep Medicine 2022.

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