Longitudinal Interventional Study on Diaphragmatic Ultrasound in Facioscapulohumeral Dystrophy (FSHD) Patients

Respiratory involvement is a recognized but underexplored manifestation of facioscapulohumeral muscular dystrophy (FSHD), reported in up to half of affected individuals. It is primarily related to weakness of the diaphragm and abdominal muscles, as well as to possible thoracic deformities. Traditional spirometric tests may underestimate early or mild inspiratory abnormalities, limiting their sensitivity for clinical monitoring. Diaphragmatic ultrasound has recently emerged as a promising tool to assess both trophism and contractility of the diaphragm. To date, only one small cross-sectional study has applied this technique in FSHD, showing reduced diaphragmatic parameters compared to controls, and no longitudinal data are currently available.

This study aims to provide the first prospective evaluation of diaphragmatic ultrasound in a cohort of genetically confirmed FSHD patients, with assessments performed at baseline and after one year of follow-up. By combining diaphragmatic ultrasound with standardized pulmonary function tests, body plethysmography, and respiratory muscle strength measurements, the study will comprehensively characterize respiratory involvement in FSHD and evaluate the potential role of ultrasound-derived indices as sensitive biomarkers.

The study design allows for the correlation of ultrasound findings with clinical and demographic characteristics, including disease duration, genetic features, and severity scores, as well as with conventional pulmonary outcomes. The longitudinal approach will clarify the ability of ultrasound to detect early or progressive respiratory impairment and its potential to complement or surpass routine respiratory function tests.

Ultimately, this project seeks to establish diaphragmatic ultrasound as a feasible and reproducible tool for the monitoring of respiratory function in FSHD. The expected results may inform the development of improved clinical guidelines for respiratory surveillance and contribute to early identification of patients who may benefit from targeted interventions, such as respiratory physiotherapy or non-invasive ventilation.