What are the main signs of muscle disease?

The primary signs of muscle disease often involve structural or functional changes within the muscle tissue. The most common indications include:

• Muscle Weakness and Atrophy: Progressive weakness and atrophy (wasting) are hallmark signs of many muscle disorders, such as muscular dystrophy. While weakness and wasting often occur together, the degree of weakness is not always proportional to the amount of muscle loss.12
• Muscle Enlargement: Abnormal muscle size, or hypertrophy, can occur. This may be true muscle growth, as seen in myotonia congenita, or pseudohypertrophy, where muscle tissue is replaced by fat, a common feature in Duchenne muscular dystrophy.1
• Involuntary Contractions: Conditions such as tetany involve intermittent spasms, while fasciculation refers to the visible twitching of muscle fibers.1
• Pain and Stiffness: While pain is relatively rare, it can result from inflammation, injury, or metabolic defects like those found in McArdle disease, which also causes stiffness and weakness upon exertion.1
• Fatigue: Persistent weakness that worsens with exercise is a primary characteristic of myasthenia gravis.12