How are congenital myopathies diagnosed?

Updated: Mar 11, 2019
  • Author: Matthew Harmelink, MD; Chief Editor: Amy Kao, MD  more...
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Answer

In the evaluation of a patient with possible congenital myopathy, consideration of the pattern of clinical phenotype, laboratory examination, and electrodiagnostic studies are the first line of evaluations to ensure that patients clinically fit. 

However, phenotypic correlation with a genetically congruent mutations is the gold standard for diagnosis. At times, however, a definitive gene is not able to be identified. In these cases, returning to muscle biopsy findings can help confirm the diagnosis based upon the known histopathologic features.

Initially, as with any child or person with weakness, localization by history and examination to a peripheral cause is prudent. Subsequently, biochemical evaluation with a creatine kinase can rapidly help narrow the differential. Significantly elelvated creatine kinase levels (>5 times the upper range of normal) is unlikely to be a congenital myopathy and other diseases such as the muscular dystrophies should be considered. However, in infants, be catious that early testing after birth (within a few days to a week) can demonstrate a falsely elevated level from baseline and may need to be rechecked.

Subsequently, electrodiagnostic evaluation can be helpful in determining neurogenci from myopathic disease in an infant and further narrow the differential. This allows the provider to proceed with genetic testing and/or muscle biopsy for further evaluation.

In previously diagnosed patients, a multidisciplinary approach is warranted given the complex care of these patients.


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