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Updated: Dec 21, 2025
Diaphragmatic Ultrasound in Adults: Image Acquisition and Interpretation
Published on: January 31, 2025
Ultrasound assessment of diaphragmatic function in type 1 spinal muscular atrophy
Danilo Buonsenso1,2, Beatrice Berti3, Concetta Palermo3
1Paediatric Unit, Department of Woman and Child Health and Public Health, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma, Italia.
Insights
Diaphragm ultrasound effectively assesses diaphragm motion and function in children with spinal muscular atrophy type 1 (SMA-1). A characteristic dysmotility pattern was observed, particularly in those with less invasive ventilation.
Area of Science:
- Neurology
- Pediatrics
- Medical Imaging
Background:
- Spinal muscular atrophy type 1 (SMA-1) is a severe neuromuscular disorder affecting diaphragm function.
- Assessing diaphragm motion and contractility is crucial for managing SMA-1 patients.
- Current functional respiratory tests may not fully capture diaphragm dysfunction.
Purpose of the Study:
- To investigate diaphragm ultrasound features in SMA-1 patients.
- To evaluate diaphragm motion, function, and contractility patterns.
- To establish the utility of ultrasound as a diagnostic tool in SMA-1.
Main Methods:
- Prospective study involving 23 SMA-1 patients and 12 controls (younger than 18).
- Diaphragm ultrasound assessed parameters including excursion, speed, thickness, and contractility patterns.
- Interrater reliability was established using Cohen's kappa coefficient.
Main Results:
- Diaphragm ultrasound values were generally within normal ranges, with no significant difference compared to controls.
- A functional gradient was observed, with SMA 1.9 subgroup showing better parameters than SMA 1.1.
- A characteristic dysmotility pattern was identified in 74% of SMA-1 patients, more prevalent in those on non-invasive ventilation (NIV) for <16 hours/day.
Conclusions:
- Ultrasound is a valuable tool for evaluating diaphragm function in SMA-1 children.
- It provides supplementary information beyond clinical and functional respiratory tests.
- A characteristic diaphragm contractility pattern exists in SMA-1, warranting further longitudinal studies.
Objective:
To investigate ultrasound features of diaphragm motion and function in type 1 spinal muscular atrophy (SMA-1) patients.
Design:
Prospective study.
Patients:
The study cohort included SMA-1 children younger than 18-year-old. Control subjects included type 2 and type 3 SMA and other neuromuscular disorders younger than 18-year-old.
Methodology:
Diaphragm ultrasound evaluating diaphragmatic excursion, speed of diaphragmatic contraction, duration of the respiratory cycle, inspiratory/expiratory relationship, end-inspiratory and -expiratory thickness, thickening fraction, and pattern of contractility. The interrater reliability for each variable was established by calculation of Cohen's k coefficient.
Results:
Twenty-three SMA-1 patients and 12 controls were evaluated. Diaphragm ultrasound values were within normal ranges in all study cohort patients and no difference was found with controls. There was a gradient of diaphragm function with SMA 1.9 subgroup having the best and SMA 1.1 having the worst parameters, particularly in end-inspiratory thickness and diaphragmatic excursion (P = .031 and P = .041, respectively). Seventy-four percent of SMA-1 patients had a dysmotility pattern of diaphragm contraction, mostly represented in SMA 1.9 subgroup (P = .001). This pattern was observed in 92.8% of children on noninvasive ventilation (NIV) for less than 16 hours/d of and in 20% patients with invasive ventilation or NIV for more than 16 hours/d (P = .027). The dysmotility pattern was never observed in the control group. The levels of interobserver agreement were high for "diaphragm irregularities," "inspiratory/expiratory relationship," and "diaphragm thickness," and good for the other variables.
Conclusions:
Ultrasound can be used to evaluate diaphragm function and contractility in SMA-1 children, providing additional information to the clinical examination and functional respiratory tests, describing a characteristic contractility pattern in these patients. Longitudinal studies are needed to understand the impact of diaphragm dysmotility and other parameters on long-term outcome in SMA-1 patients.
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