Congenital myopathy vs muscular dystrophy have similar symptoms in many aspects and are sometimes mistaken for one another. Although both affect the skeletal muscles, their appearance and symptoms vary greatly.
Knowing the differences can help individuals understand these diseases and their impact on the people that suffer from them.
Congenital myopathy usually affects individuals most often in the perinatal period. This is not always the case and myopathies can manifest early in infancy or childhood. People that develop these diseases later tend to suffer less extreme symptoms than those who develop it in the perinatal stage.
Congenital myopathy doesn't present the type of deterioration that muscular dystrophy does, and if there is any progression of the disease, it is minimal and slow. In the mildest cases, myopathy creates a weakness in the limbs. Adults with the disease in its mildest form tend to be intolerant to exercise.
Many people born with congenital myopathy do not have the same muscle tone of a normal newborn and can seem as though they are floppy. Some of the other characteristics of this disease are a lack of normal movement that other newborns and infants exhibit early in life as well as a delay of motor skills and learned movement milestones.
They also develop arthrogryposis or bony deformities that begin to appear after birth. Congenital hip displacement is also a hallmark symptom of congenital myopathy. There are several different types of congenital myopathies including central core disease, nemaline myopathy, centronuclear myopathy, and congenital fiber type disproportion.
Many of the individuals afflicted with muscular dystrophy have merosin-deficient CMD. Doctors and scientists believe that roughly half of the individuals diagnosed with muscular dystrophy fall into this category. In this form, muscular dystrophy is a severe phenotype and presents arthrogryposis and deformities of the joints at birth.
The risk of death from respiratory failure is significant with this form of muscular dystrophy. A ventilator helps weak infants survive the early stages of life once they have received the diagnosis, and it can eventually be removed if the baby responds positively and seems to have enough muscle strength to maintain respiration on their own.
In the long term, babies can eventually learn to sit up by themselves, but other milestones such as standing and walking are usually not possible for people with muscular dystrophy. Neural development is normally on track for those with the disease and although there can be slight developmental delays, these are normally a symptom of the seizures that tend to occur over their lifetime.
Another type of muscular dystrophy is called merosin positive CMD. This particular type tends to be less severe and the brain doesn't appear affected by the disease itself. Unlike merosin-deficient CMD, merosin positive CMD does not prevent the individual from learning how to stand and walk. This form of muscular dystrophy does delay the motor skill function to some degree, but they usually are able to stand and walk by the age of four.
The symptoms are much like those of a myopathy with the exception that some contractures can develop later in life. Some other types of muscular dystrophy include Fukuyama CMD, Muscle-Eye-Brain, and Walker-Warburg Syndrome.
Although there can be many similarities between congenital myopathy and muscular dystrophy, the symptoms of each can depend on what particular type of each disease is present in the patient. Congenital myopathy although somewhat debilitating is not prone to much progression and remains static.
Congenital muscular dystrophy can range from the most severe form, merosin-deficient, to the milder form, merosin-positive, that exhibits many of the same symptoms that myopathy presents. It tends to become less debilitating and present symptoms of weakness more than progressive degeneration. It does, however, create the possibility of arthrogryposis and contractures over time.
While congenital myopathy and muscular dystrophy both have much of the same skeletal muscle weakness, they are, in fact, quite different in terms of progression and long-term prognosis. Knowing the difference can help individuals understand more about the people that suffer from these diseases.