Congenital Myopathies
Primary manifestation: delayed motor milestones.
Congenital Muscular Dystrophies
Congenital myotonic dystrophy, congenital muscular dystrophies: muscle destruction, replacement by fat and connective tissue on muscle biopsy.
Congenital muscular dystrophies vs. congenital myopathies: previously distinguished by progressive vs. static course. Distinction obsolete, as both groups include static and progressive disorders.
Specific disorders listed in Table 128.1.
Congenital Myopathies
General Features
Classification: historically defined by distinctive structural, histochemical features on muscle biopsy (Table 128.2). Often marked by aggregation of defective, mutant proteins, leading to gene- and protein-based nosology (Table 128.3). Most are familial.
Clinical features: delayed motor developmental milestones; child moves less than expected in neonatal period (“floppy baby syndrome”). Symptom onset sometimes delayed until adult years. Weakness may progress slowly or not at all. Heart occasionally affected.
Investigations: serum CK normal or mildly elevated. EMG: normal or mild myopathic features.
Diagnosis: based on muscle pathology. Other congenital syndromes include MG, congenital myotonic dystrophy, spinal muscular atrophy.
Treatment: symptomatic.
Table 128.1 Congenital Muscular Dystrophies | |
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Central Core Disease
Typically autosomal dominant with variable penetrance.
Proximal limb weakness, hypotonia, absent tendon reflexes, delayed motor milestones. Normal examination in up to one third. Less common: dysmorphic features (club feet, scoliosis, hip dislocation, finger contractures). Bulbar muscles spared. Increased risk for malignant hyperthermia.
Table 128.2 Morphologic Classification of Congenital Myopathies | ||||||||||||||
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