Congenital myopathy
- Article
- 2021-03-07
Myopathy is a muscle condition that usually results in weakness. Congenital myopathy refers to a group of muscle disorders that occur at birth or in childhood. Typically, a baby with congenital myopathy will be "floppy", have difficulty breathing or eating, and lag other babies in achieving normal developmental milestones, such as turning around or sitting up.
Muscle weakness can occur for many reasons, including a problem with the muscle, a problem with the nerve that stimulates the muscle, or a problem with the brain. Therefore, to diagnose congenital myopathy, a neurologist will perform a detailed physical exam and run tests to determine the cause of weakness. If a myopathy is suspected, possible tests include a blood test for a muscle enzyme called creatine kinase, an electromyogram (EMG) to evaluate the electrical activity of the muscle, a muscle biopsy, and genetic testing.
There are currently seven different types of congenital myopathy, with some variation in symptoms, complications, treatment options, and outlook.
Nemaline myopathy is the most common congenital myopathy. Babies usually have problems breathing and eating. Skeletal problems can develop later, such as scoliosis (curvature of the spine). In general, the weakness does not worsen during life.
Myotubular myopathy is rare and only affects boys. Weakness and flaccidity are so severe that a mother may notice decreased movements of the baby in her womb during pregnancy. There are usually significant breathing and swallowing problems; many children do not survive childhood. Osteopenia (weakening of the bones) has also been associated with this condition.
Centronuclear myopathy is rare and starts in childhood or early childhood with weakness of the arms and legs, drooping eyelids and problems with eye movement. Weakness often gets worse with time.
Central core disease varies among children in the severity of the problems and the degree of their worsening over time. There is usually mild flaccidity in childhood, delayed milestones and moderate limb weakness, which do not get much worse over time. Children with central core disease can have life-threatening reactions to general anesthesia. Treatment with the drug salbutamol has been shown to significantly reduce weakness, although it does not cure the condition.
Multi-minicore disease has several subtypes. Most of them have severe limb weakness and scoliosis. Breathing difficulties also often occur. Some children have weakened eye movements.
Fiber-type congenital myopathy is a rare condition that starts with flaccidity, weakness of limbs and face, and difficulty breathing.
Hyaline body myopathy is a condition characterized by the specific appearance under the microscope of a muscle tissue sample. It probably has several causes. As a result, the symptoms are quite variable.
Therapy
Currently, only central core disease has an effective treatment (see above). There are no known treatments for these conditions. Supportive treatment can include orthopedic treatments as well as physical, occupational or speech therapy.
Prognosis
If the breathing difficulties are severe, and especially if there are also problems with eating and swallowing, babies can die from respiratory failure or complications such as pneumonia. Sometimes muscle weakness can lead to skeletal problems such as scoliosis, decreased joint mobility or hip problems. The heart muscle is rarely involved.
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