Late-onset Becker muscular dystrophy: Refining the clinical features and electrophysiological findings.

Introduction: The aim of this study was to characterize a unique distribution of muscle involvement in sporadic Becker muscle dystrophy (BMD).

Methods: Retrospective chart review, clinical examination, electrophysiological studies, cardiac testing, and genetic testing were performed in 5 patients.

Results: Predominant weakness and atrophy of biceps brachii, hip adduction, and quadriceps muscles was noted along with calf and extensor forearm hypertrophy. Finger flexor muscles were severely weak in 3 of 5 patients, a feature that could lead to a misdiagnosis of inclusion body myositis. Creatinine kinase was only mildly elevated in most patients. Electromyography was abnormal in all patients. Muscle biopsy in 1 patient demonstrated normal immunostaining for dystrophin.

Conclusions: We found a unique and uniform distribution of muscle involvement in 5 sporadic cases of BMD. Recognizing these features is important for differentiating it from other myopathies that may have similar features and avoids unnecessary invasive procedures such as muscle biopsy.