Background: Muscle biopsy is performed to confirm the diagnosis of neuromuscular disease and guide therapy. The purpose of our study was to determine if muscle biopsy changed patient diagnosis or treatment, which patients were most likely to benefit from muscle biopsy, and complications resulting from muscle biopsy.
Materials and methods: An IRB-approved retrospective chart review of all patients less than 18 years old undergoing muscle biopsy between January 2010 and August 2016 was performed. Demographics, patient presentation, diagnosis, treatment, hospital course, and follow-up were evaluated. Descriptive and comparative (student's t test, Mann-Whitney U, and Fisher's exact test) statistical analysis was performed. Medians were reported with interquartile range (IQR).
Results: 90 patients underwent a muscle biopsy. The median age at biopsy was 5 years (2, 10). 37% (n = 34) had a definitive diagnosis. 39% (n = 35) had a change in their diagnosis. 37% (n = 34) had a change in their treatment course. In the 34 patients who had a change in their treatment, the most common diagnosis was inflammatory disease at 44% (n = 15). In the 56 patients who did not have a change in treatment, the most common diagnosis was hypotonia at 30% (n = 17). There was no difference in patients who had a change in treatment based on pathology versus those that did not. The median length of follow-up was 3 years (1, 5).
Conclusions: Muscle biopsy should be considered to diagnose patients with symptoms consistent with inflammatory or dystrophic muscular disease. The likelihood of this altering the patient's treatment course is around 40%.
Keywords: Hypotonia; Muscle biopsy; Muscular dystrophy; Myopathy; Myositis.