Facioscapulohumeral muscular dystrophy

Updated June 20, 2024

What's new

Updated 2023 ACCP and 2022 HRS guidelines for the diagnosis and management of facioscapulohumeral muscular dystrophy.

Background

Overview

Definition

Facioscapulohumeral muscular dystrophy is an autosomal dominant inherited disorder characterized by asymmetric and progressive weakness of the muscles of the face, scapular, and humeral muscles, followed by weakness of distal lower extremities and pelvic girdle.

Pathophysiology

Facioscapulohumeral muscular dystrophy is caused by a genetic abnormality with contraction of a part of a repeated sequence in the D4Z4 region on chromosome 4q35 and mutations in gene SMCHD1.

Disease course

Clinical manifestations of facioscapulohumeral muscular dystrophy include progressive weakness of the facial, shoulder arm muscles, foot drop, asymmetrical abdominal weakness (Beevor's sign), paraspinal muscle weakness, bent-spine, limb-girdle patterns, asymptomatic atrial arrhythmias, hearing loss, retinal vascular changes, and respiratory involvement that leads to patients wheelchair-bound.

Prognosis and risk of recurrence

Facioscapulohumeral muscular dystrophy is not associated with increased mortality.

Guidelines

Key sources

The following summarized guidelines for the evaluation and management of facioscapulohumeral muscular dystrophy are prepared by our editorial team based on guidelines from the American College of Chest Physicians (ACCP 2023), the Heart Rhythm Society (HRS 2022), the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM/AAN 2015), and the European Federation of Neurological Societies (EFNS 2011).

Classification and risk stratification

Severity prediction: as per AAN/AANEM 2015 guidelines, recognize that patients with large D4Z4 deletion sizes (contracted D4Z4 allele of 10-20 kb) are more likely to develop a more significant disability, and at an earlier age, and symptomatic extramuscular manifestations.

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Diagnostic investigations

Genetic testing: as per AAN/AANEM 2015 guidelines, obtain genetic confirmation of facioscapulohumeral muscular dystrophy type 1 in patients with atypical presentations and no first-degree relatives with genetic confirmation of the disease.

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Respiratory support

Airway clearance: as per ACCP 2023 guidelines, consider offering glossopharyngeal breathing for lung volume recruitment and airway clearance in patients with hypoventilation.

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Medical management

Management of strength: as per AAN/AANEM 2015 guidelines, avoid using albuterol, corticosteroids, or diltiazem to improve strength in patients with facioscapulohumeral muscular dystrophy.

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Nonpharmacologic interventions

Aerobic exercises: as per AAN/AANEM 2015 guidelines, consider encouraging patients with facioscapulohumeral muscular dystrophy to engage in low-intensity aerobic exercise programs, guided by experienced physical therapists.

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Surgical interventions

Scapular fixation: as per AAN/AANEM 2015 guidelines, consider performing surgical scapular fixation cautiously in selected patients after careful consideration of the overall muscle impairment in the involved arm, assessment of potential gain in the ROM by manual fixation of the scapula, the patient's rate of disease progression, and the potential adverse consequences of surgery and prolonged post-surgical bracing.

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