Longitudinal Study on Diaframmatic Ultrasound in FSHD Patients

The goal of this prospective, longitudinal, single-center study is to describe respiratory function in patients affected by FSHD at baseline and after one year using both diaphragmatic ultrasound and pulmonary function test. The primary questions this study aims to answer are:

1. How does respiratory function assessed by diaphragmatic ultrasound and pulmonary function tests change over 12 months in FSHD patients?
2. How accurate is diaphragmatic ultrasound in detecting respiratory abnormalities in these patients compared to pulmonary function tests?
3. What is the relationship between ultrasound and functional indices, and how do these indices correlate with demographic, clinical, and genetic data?

To achieve this, we will enroll a cohort of 34 patients affected by FSHD, and each of them will undergo a comprehensive neurological examination, body plethysmography, measurement of maximal inspiratory pressure (MIP) and maximal espiratory pressure (MEP) and nocturnal oximetry at baseline and after 12 months.

Respiratory disorders are reported to be present in 38-48% of patients with Facioscapulohumeral Muscular Dystrophy (FSHD) and are caused mainly by the weakness of the diaphragm muscle, abdominal muscles, and possible chest deformities. Pulmonary assessment is an integral part of managing these patients; however, spirometric parameters may underestimate mild inspiratory abnormalities. Diaphragmatic ultrasound is a promising technique used to evaluate diaphragm trophism and kinetics: only one study has assessed respiratory function using diaphragmatic ultrasound in a small cohort of FSHD patients, demonstrating a significant reduction in some ultrasound parameters. Currently, no data are available in the literature regarding the long-term follow-up use of diaphragmatic ultrasound in FSHD patients.

The primary objective of this prospective, single-center, longitudinal study is to assess respiratory function indices derived from diaphragmatic ultrasound in FSHD patients at baseline and after one year.

The secondary objectives are as follows:

* Describe the differences in respiratory function parameters of a cohort of FSHD patients using both diaphragmatic ultrasound and pulmonary function tests at baseline and after 12 months
* Evaluate the diagnostic accuracy of ultrasound parameters in detecting respiratory abnormalities.
* Assess the relationship between ultrasound and functional pulmonary test parameters at baseline and after 12 months and the relationship between these indices and clinical, demographic, and genetic data

We will recruit 34 patients with genetically confirmed FSHD who are regularly monitored at the Neurology and Pneumology Unit of Fondazione Policlinico Universitario Agostino Gemelli IRCCS as part of their routine follow-up for this condition.

Inclusion criteria are as follows:

* Age 18 years or older.
* Genetically confirmed diagnosis of FSHD.
* Signed written informed consent to participate in the study.

Exclusion criteria are:

* Age under 18 years.
* History of trauma and/or surgical interventions and/or radiotherapy in the neck and mediastinum (e.g., total thyroidectomy, mastectomy) with evidence of phrenic nerve injury.
* Refusal to sign the written informed consent to participate in the study.

All patients will undergo the following examinations at baseline (T0) and at 12 months + 3 months (T1):

* Neurological examination (as per routine clinical practice). Demographic and clinical data will be collected, including age, gender, BMI, EcoRI fragment length, disease duration, Clinical Severity Score (CSS), FSHD Comprehensive Clinical Evaluation Form (CCEF), Medical Research Council Score for manual muscle testing (MRC), scoliosis or other spine deformities.
* Pneumology examination (as per routine clinical practice), including medical history and pulmonary assessment (presence of pulmonary comorbidities or other conditions that may affect respiratory function, e.g., smoking, COPD, etc.).
* Diaphragmatic ultrasound, using the MyLab TM 50 Gold Cardiovascular ultrasound machine (Esaote Spa, Rome, Italy), in both semi-supine (where possible) and sitting positions. Bilateral diaphragm thickness (DT) and diaphragm kinetics (change in diaphragm thickness) will be evaluated. Diaphragmatic excursion amplitude will also be calculated to assess cranio-caudal diaphragm movements.
* Body plethysmography (as per routine clinical practice), including FRC (functional residual capacity: static volume of air remaining in the lungs after a normal expiration) and TLC (total lung capacity: static volume of air in the lungs at the end of maximal inspiration).
* Measurement of Maximal Inspiratory Pressure (MIP) and Maximal Expiratory Pressure (MEP) (as per routine clinical practice).
* Nocturnal oximetry (as per routine clinical practice).

Eligibility Criteria:
Inclusion Criteria:

* Diagnosis of FSHD, genetically confirmed.
* Adult patients (18 years or older)
* Signature from the patient on the written informed consent document

Exclusion Criteria:

- Medical history of neck and mediastinal trauma and/or surgery and/or radiation therapy (e.g. total thyroidectomy, mastectomy) with evidence of phrenic nerve injury.