Myopathy is a type of muscular disease, characterized by improper functioning of the muscle fibers, causing muscular weakness. It is a disease of the muscles, which can be either neuromuscular, or musculoskeletal in nature.
Onset of muscular weakness of the proximal muscles is the classical symptom of myopathy. This is followed by development of muscle cramps and pain. In majority of the cases, myopathy significantly affects the pelvic girdle muscles, than the muscles of the shoulder girdle.
Myopathies, that occur due to inflammatory disease, such as myositis, cause development of weakness in the fingers and quadriceps. Such a type of condition, majorly affects the older population. Affected individuals may also suffer from fever. In addition, other signs and symptoms include the following:
The following tests are employed for diagnosing several types of myopathies:
The prognosis of myopathy is favorable, if the underlying condition can be successfully treated, such as in cases of endocrine myopathies. Congenital myopathy has a poor prognosis rate, and children gradually fall prey to muscular weakness, as they grow up. The myopathies that develop later in life have a much better prognosis, than the congenital type .
Myopathy can be acquired or inherited in nature. The following are the various causative factors, which can cause such a type of muscular disease :
It has also been estimated, that the worldwide prevalence of inheritable myopathy is about 14%. In US, the incidence of Duchenne and Becker MD is about 1 in every 3300 boys. Inflammatory myopathies occur in about 5 to 10 individuals per 100,000 people. This condition is particularly common in women than men.
The mortality and morbidity profile of myopathy, depends on the severity and causative factors. In case of severe weakness, the individual can suffer from respiratory failure, causing death. Polynesians are at an increased risk of contracting the disease condition .
Inherited myopathy, or the congenital form, progresses slowly, over a period of several years. Factors such as infections, genetic abnormalities, inflammation, toxins and electrolyte imbalances, can cause acute or chronic myopathies to set in. These factors cause significant disruption of metabolic processes, along with the structural integrity of the muscle cells. Such sequence of events can cause muscle weakness to develop, which in more advanced and severe cases, can lead to periodic paralysis .
Not all forms of myopathy can be prevented. Only those that have genetic links can be prevented, through counseling imparted in the early stages. Prenatal diagnosis for testing of genetic abnormalities in the fetus, can also prevent the development of congenital myopathies. Inflammatory myopathies that develop as a result of infectious agents cannot be always prevented, as it is almost impossible to predict the onset of such a type of condition .
Muscle weakness sets in as a result of abnormalities, which occur in the cell structure of the muscles and metabolism. Myopathy can be classified under two categories, acquired and inherited. In many circumstances, the condition can also significantly affect the cardiac muscles, as a result of which dilated cardiomyopathy or hypertrophic cardiomyopathy can set in .