What is the role of biopsy in the workup of congenital myopathies?

Updated: Mar 11, 2019
  • Author: Matthew Harmelink, MD; Chief Editor: Amy Kao, MD  more...
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The utility of muscle biopsy has changed significantly over the past few decades. While traditionally the muscle biopsy would be an early step, and conducted prior to genetic testing, this trend is changing. With the cheaper, more rapid turnaround of genetic testing, looking to genotyping patients as first-line evaluations in patients who are not critically ill can be considered.

In critically ill neonates, a muscle biopsy may provide a category of disease as well as give some indication of severity based upon histopathologic features. However, genetic identification remains the ideal standard to allow for further counseling.

The biopsy should be conducted in a muscle that is weak but that retains bulk and some strength. Typically, the vastus lateralis remains an ideal muscle of choice. The evaluation should be undertaken at a facility skilled with both procuring, processing, and evaluating muscle biopsies given technical aspects can limit interpretation. Additionally, availability of muscle-specific testing and electron microspcopy can be helpful in diagnosis.

Finally, in infants and neonates who have mild symptoms, an early biopsy may be normal and need to be repeated years later after the pathologic features have been able to develop.

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