Open muscle biopsy in suspected myopathy: Diagnostic yield and clinical utility

Background: The purpose of the study was to investigate the diagnostic yield and clinical utility of open muscle biopsy and to identify pre-biopsy factors that might predict useful clinical results for suspected myopathy. Methods: Two-hundred fifty-eight muscle biopsies, performed for investigation of suspected myopathy, were evaluated. Results: A specific clinical diagnosis following muscle biopsy was made in 43% of cases. As a result of the biopsy, clinical diagnosis was changed in 47% and treatment was changed in 33% of cases. Results either led to a specific clinical diagnosis or changed the diagnosis/treatment in 74% of patients. Positive family history of myopathy and findings of myopathic irritability on electromyography had a negative predictive value for diagnosis change. Conclusions: Open muscle biopsy is useful in myopathy evaluation in the modern genetic era.