Myopathies are defined as diseases of skeletal muscle and can have many causes. Accordingly, myopathies can present in a variety of ways, but one of the cardinal features is muscle weakness. Weakness can affect muscles of the eyes, face, arms, legs, trunk, swallowing, and breathing. While certain myopathies can present with muscle pains, cramps, and stiffness, these features are non-specific to myopathies and can be seen in many other diseases, including those outside the realm of neuromuscular disorders. The most common myopathies seen in the Neuromuscular Center are inflammatory myopathies, muscular dystrophies, metabolic myopathies, myopathies associated with systemic disorders, and myopathies due to certain medications.
As with peripheral neuropathies and MG, the diagnosis of myopathies requires a neurologic history and examination. Laboratory tests are used to measure enzymes of the muscles and look for associated systemic disorders. While the EDX examination can play a diagnostic role, the ‘gold standard’ for most myopathies requires a muscle biopsy. This procedure is performed on an outpatient basis by an experienced physician. The muscle biopsies are carefully prepared and undergo extensive analysis in the Cleveland Clinic Surgical Pathology laboratory to determine the existence of myopathies. On occasion, muscle specimens may be sent to outside facilities for special stains.
The treatment of myopathies is multidisciplinary and depends on the type of myopathy. Certain types of myopathies can be treated with immune-suppressant agents and IVIG. Most myopathies require the use of supportive services, such as physical and occupational therapy, pulmonary medicine, cardiology, dietary management, and speech/swallowing therapists. Surgical treatment of spine and limb deformities is used in long-standing cases.