Diseases of the muscles and the neuromuscular junction have a common symptom, namely loss of strength. Atrophy and cramps are other features. Many muscular diseases have a genetic cause and are often difficult to treat, but this is why it is very important to recognize acquired diseases, as a good deal can usually be done about them therapeutically. When classifying muscular diseases a distinction needs to be made between proximal and distal myopathies, and between diseases with and without myotonia. Myasthenia is a special case: unlike many other disorders discussed in this chapter, it often causes diplopia, and the severity of the symptoms fluctuates. Myasthenias are usually autoimmune diseases and as such respond well to treatment, but incorrect treatment can cause life-threatening situations. In cases of muscular disease, consideration needs to be given to cardiopulmonary involvement, care should be taken with anaesthesia, and good genetic advice must be given.
