G71.02 Facioscapulohumeral muscular dystrophy

Name of the Condition

• Facioscapulohumeral muscular dystrophy

Summary

Facioscapulohumeral muscular dystrophy (FSHD) is a genetic disorder characterized by progressive muscle weakness and degeneration, primarily affecting the face, shoulder girdle, and upper arms. The condition results from genetic mutations that disrupt muscle protein function, leading to impaired muscle integrity over time. Severity and progression vary among individuals, with symptoms often emerging in adolescence or early adulthood.

Causes

FSHD is caused by genetic mutations involving the D4Z4 repeat region on chromosome 4, which affects the expression of the DUX4 gene. This disruption leads to abnormal production of the DUX4 protein, toxic to muscle cells and resulting in progressive muscle damage. The condition is inherited in an autosomal dominant pattern, meaning a single copy of the mutated gene from one parent can cause the disorder.

Risk Factors

• Family history of FSHD.
• Inheritance of the autosomal dominant mutation.
• Age (symptoms typically appear in late teens to early adulthood, though onset can vary).

Symptoms

• Progressive weakness in facial muscles (e.g., difficulty smiling, whistling).
• Shoulder girdle weakness (e.g., difficulty raising arms, winging scapula).
• Upper arm muscle atrophy.
• Mild lower body involvement in some cases.
• Asymmetric muscle weakness (affecting one side more than the other).
• Potential hearing loss or retinal vascular abnormalities in rare cases.

Diagnosis

Diagnosis involves clinical evaluation of muscle weakness patterns, family history assessment, and genetic testing to confirm the D4Z4 repeat mutation. Additional tests may include electromyography (EMG) to assess muscle electrical activity, muscle biopsy (rarely needed), and imaging to evaluate muscle structure. Blood tests for muscle enzymes (e.g., creatine kinase) may show mild elevations but are not diagnostic.

Treatment Options

Treatment focuses on managing symptoms and maintaining function. Interventions may include physical therapy to preserve mobility, orthopedic devices (e.g., braces) for support, pain management, and respiratory monitoring if weakness affects breathing. Experimental therapies targeting the underlying genetic mechanism are under investigation.

Prognosis and Follow-Up

Prognosis varies; many individuals remain ambulatory throughout life, though some may require assistive devices. Regular follow-up with a neurologist or neuromuscular specialist is recommended to monitor progression, manage complications, and adjust care plans. Lifespan is typically unaffected, but quality of life may decline with advancing weakness.

Complications

• Progressive muscle weakness leading to functional limitations.
• Chronic pain or discomfort.
• Respiratory insufficiency (rare, in advanced cases).
• Hearing loss or visual abnormalities (rare).
• Psychological impact due to physical changes.

Lifestyle & Prevention

While FSHD cannot be prevented, lifestyle measures can support quality of life. Regular low-impact exercise (e.g., swimming) may help maintain muscle function. Avoiding overexertion and using assistive devices (e.g., wheelchairs for long distances) can reduce fatigue. Genetic counseling is recommended for affected individuals and their families.

When to Seek Professional Help

Seek medical attention if you experience unexplained facial or shoulder weakness, difficulty with daily activities (e.g., lifting objects), or notice asymmetric muscle loss. Prompt evaluation is important for early diagnosis and intervention to slow progression.

Tips for Medical Coders

Document the clinical findings supporting FSHD, including muscle weakness patterns, family history, and genetic test results when available. Ensure the code G71.02 is used only when the diagnosis is confirmed as facioscapulohumeral muscular dystrophy, distinguishing it from other muscular dystrophy subtypes. Include details on symptom onset and progression for accurate coding and billing.