A few neuromuscular diseases affect facial muscles, and these too are 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 in large part on the pattern of muscle involvement detected during the clinical examination. Knowledge of other cases in the family can help to confirm a diagnosis.
Diseased muscle has an electrical activity characteristically different from normal muscle.
The EMG can also provide information on whether the nerve controlling muscle activity is functioning normally. 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 can be important aids in the diagnosis of neuromuscular diseases.