Differentials
Polymyositis
SIGNS / SYMPTOMS
Polymyositis can occur at 4-7 years of age, and muscle contractures and weakness can become as severe as those of DMD. Muscle weakness usually occurs in the proximal muscles, especially those of the shoulder and pelvic girdles.
INVESTIGATIONS
Diagnosis is established by characteristic muscle biopsy findings of inflammation, including mononuclear invasion of nonnecrotic muscle, CD8+ cytotoxic/suppressor T cells, macrophages, and absence of perifascicular atrophy of dermatomyositis.
Static encephalopathies (cerebral palsy)
SIGNS / SYMPTOMS
The great majority of children who walk on their toes have static encephalopathies and at least mild spasticity. In many cases the children are asymmetrically affected.
Children with DMD are hypotonic and tend to be symmetrically affected.
INVESTIGATIONS
Cerebral palsy is diagnosed clinically by the finding of central nervous system involvement marked by spasticity (not seen in neuromuscular diseases) as well as cognitive, motor, and sensory involvement.
Brain MRI is abnormal in around 80% of patients with cerebral palsy.[27]
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