Science News: Spinal Muscular Atrophy Type 1 Survival Without New Pharmacotherapies: Two Treatment Paradigms

Submitted by: Nandita Keole, MD
Edited by: Milvia Pleitez, MD

Citation: Bach JR, Saporito L, Weiss W. Spinal muscular atrophy type 1 survival without new pharmacotherapies: Two treatment paradigms. Am J Phys Med Rehabil. 2024;103(3):233-237. doi:10.1097/PHM.0000000000002354

Summary: This is an observational study that aims to present noninvasive respiratory management outcomes using continuous positive pressure noninvasive ventilatory support (CNVS) and mechanical in-exsufflation (MIE) from infancy for spinal muscular atrophy (SMA) type 1. Additionally, the study looks at the outcomes and bearing on new medical therapies.

Noninvasive ventilatory support was begun for consecutively referred symptomatic infants with SMA type 1 from 1 to 10 months of age. Intercurrent episodes of respiratory failure were managed by intubation then extubation to CNVS and MIE despite failing ventilator weaning and extubation attempts. Intubations, tracheotomies, and survival were monitored.

Results: Of 153 patients with SMA type 1 consecutively referred since 1995, 37 became CNVS dependent, almost half before 10 years of age. Of the 37, 18 required CNVS for a mean 18.6 ± 3.3 years to a mean 25.3 (range, 18–30) years of age, dependent from as young as 4 months of age with 0 to 40 ml of vital capacity. One of the 18 died from COVID-19 acute respiratory distress syndrome at age 24 after 23 years of continuous noninvasive ventilatory support. Extubation success rate of 85% per attempt (150/176) resulted in only one undergoing tracheotomy.

Conclusions: Medical treatments begun during the first 6 weeks of age convert SMA 1 into SMA type 2 or 3, but cough flows remain inadequate to avoid many pneumonias. The pneumonias when resolved by a treatment paradigm of extubation to CNIVS and MIE, eliminate the need to resort to tracheotomies. The regimen of NVS and MIE prevent perhaps 90%, but not all pneumonias or need for intubations. However, even when SMA1 CNVS users are ventilator unweanable for months to years before requiring intubation for pneumonia or general anesthesia, they can almost invariably be extubated back to CNVS and MIE. With or without gene therapy or other upstream medications for SMA, cough flows remain suboptimal and result in URI-pneumonias and intubations. Since 2018 the practice has only had three patients (who were treated with the newer medications) referred that were intubated and unweanable. After successful extubations to CNVS, however, all three returned to their states. They subsequently died when NVS and MIE were not available to them.

Comments: This paper refers to appropriate use of MIE and CNVS to help patients with lower vital capacity maintain survival. It highlights the need to properly use an available modality of treatment appropriately to help keep SMA type 1 alive without the need for tracheostomies. This is something even more important in cases when tracheostomies are declined by the families.