Monroe Carell Jr. Children's Hospital at Vanderbilt
Monroe Carell Jr. Children's Hospital at Vanderbilt
Monroe Carell Jr. Children's Hospital at Vanderbilt
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Monroe Carell Jr.
Children's Hospital
at Vanderbilt
2200 Children's Way
Nashville, TN 37232

(615) 936-1000

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Diagnostic Services


Clinical examination

The clinical examination focuses on muscle strength. Special attention is given to muscles in the arms, legs, shoulders, and hips. Facial muscles are also examined. Determining which muscles are not weak is as important as determining which muscles are weak. Each neuromuscular disease typically shows a specific pattern of muscle involvement. A final diagnosis is based on the pattern of muscle involvement detected during the clinical examination.

Family history

Many neuromuscular diseases, including all of the muscular dystrophies, are genetic diseases. Knowledge of other cases in the family can help to confirm a diagnosis.


Diseased muscle has an electrical activity characteristically different from normal muscle. An electromyogram (EMG) measures electrical activity of muscle. The EMG can also provide information on whether the nerve controlling muscle activity is functioning normally. Electrodiagnosis in small children usually requires sedation. This procedure is scheduled separately and is not performed in the clinic. 

Serum enzyme tests

Serum enzyme tests measure the amount of muscle proteins present in the blood. Where muscle tissue is healthy, these proteins remain in muscle and the amount present in blood is relatively low. Many, but not all, neuromuscular diseases that cause muscle destruction lead to a significant increase in the muscle protein levels found in the blood. Thus, serum enzyme tests are important to the diagnosis process. Creatine Kinase (CK) is a protein that is confined almost exclusively to muscle. A higher than normal CK level in blood serum indicates a leakage from muscle tissue. Determination of the serum CK level is an important laboratory test in the diagnosis of Duchenne muscular dystrophy. CK testing of younger siblings (usually male) of those with Duchenne muscular dystrophy enables physicians to detect preclinical cases.

Genetic tests

A small amount of blood can be used to provide DNA. This is extremely valuable for diagnosing genetic defects that cause specific neuromuscular diseases. One of the strengths of these tests is that they reveal the same abnormality regardless of disease stage.

Muscle biopsy

Muscle tissue is surgically removed (a muscle biopsy) for microscopic and/or biochemical analysis. For some neuromuscular diseases, a final diagnosis depends on the analysis of a muscle biopsy. The amount of muscle removed is roughly equivalent in size to the tip of a little finger. The muscle tissue can be analyzed for abnormalities in the protein dystrophin within muscle cells. Dystrophin is absent or greatly diminished in concentration in the muscle cells of those with Duchenne muscular dystrophy. It is present in an abnormally low amount or altered form in the muscle cells of those with Becker muscular dystrophy.

Last Edited: June 30, 2016
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