Acquired skeletal muscle disease

Acquired skeletal muscle disease (Orphanet code 206638) is a broad classification encompassing a group of disorders affecting skeletal muscle that are not inherited but rather develop during a person's lifetime due to external or secondary causes. These conditions are distinguished from hereditary myopathies in that they arise from identifiable triggers such as autoimmune processes, infections, toxic exposures, endocrine disorders, or other systemic conditions. The skeletal muscles — the voluntary muscles responsible for movement and posture — are the primary body system affected, though secondary effects on the respiratory, cardiac, and other systems may occur depending on the specific underlying cause. Key clinical features common across acquired skeletal muscle diseases include progressive or episodic muscle weakness, muscle pain (myalgia), fatigue, exercise intolerance, and in some cases muscle wasting (atrophy). The distribution of weakness can vary, often affecting proximal muscles (those closest to the trunk, such as the hips and shoulders), which may lead to difficulty climbing stairs, rising from a seated position, or lifting objects overhead. Some forms may also involve dysphagia (difficulty swallowing) or respiratory muscle weakness. Treatment depends on the specific underlying etiology. For inflammatory and autoimmune forms (such as polymyositis or dermatomyositis), immunosuppressive therapies including corticosteroids and steroid-sparing agents are commonly used. For toxic or drug-induced myopathies, removal of the offending agent is the primary intervention. Endocrine myopathies are managed by correcting the underlying hormonal imbalance. Supportive care including physical therapy and rehabilitation plays an important role across all subtypes. Prognosis varies widely depending on the specific cause, severity, and timeliness of treatment.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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