Following clinical examination and analysis of the laboratory tests, many neuromuscular diseases can be quickly and accurately diagnosed. Some neuromuscular diseases, however, can be more difficult to diagnose. In these cases, the physician will make what is called a differential diagnosis listing two or more diseases that have similar symptoms. A definitive diagnosis may require waiting until the disease has progressed to a stage that is unique to that disease. With the majority of neuromuscular diseases, the first noticeable symptom is usually a persistent weakness in one or more muscles.
Muscles can become weak for many reasons.
The following describes the most common diagnostic and laboratory procedures used to determine why muscle function is abnormal and to arrive at a definitive diagnosis. The clinical examination of someone suspected of having a neuromuscular disease focuses on muscle strength. Muscles are examined with special attention given to those of the arms, legs, shoulders and hips. 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.