Congenital Myopathies

Types of Congenital Myopathy Image

Congenital myopathies are muscle disorders that affect the skeletal muscles from birth. Most types of congenital myopathy occur when both parents carry the genes for the disease, but some are due to a single dominant gene that overrides the health gene.

Congenital myothapthy symptoms range from mild muscular weakness to fatal respiratory distress, depending on which type of myopathy is present.

Types of congenital myopathy number in the hundreds, but five types stand out as the most common:

  • central core disease
  • congenital fiber type disproportion
  • multicore myopathy
  • myotubular myopathy
  • nemaline myopathy.

Central Core Disease

Central core disease can occur when a single parent carries the gene for the disease. Infants may have poor muscle tone and mild leg muscle weakness. Delays in walking occur due to central core disease symptoms, but the condition does not worsen with age.

Congenital Fiber Type Disproportion

Like so many types of congenital myopathy, congenital fiber type disproportion is an inherited condition. Common symptoms include weakness of the face, arm leg, neck and trunk muscles. Children with congenital fiber type disproportion may also have skeletal abnormalities. A small percent of affected infants develop respiratory failure.

Congenital fiber type disproportion symptoms may progress during the first year of life, but then the condition stops progressing. As a general rule, children with congenital fiber type disproportion are small for their age.

Multicore Myopathy

Multicore myopathy usually causes a mild muscle weakness in infants that may or may not be progressive. The condition is sometimes associated with heart conditions and may make nighttime breathing difficult.

Myotubular Myopathy

Congenital myopathy symptoms are often present from birth, but some congenital myopathies become symptomatic later in life. Myotubular myopathy may do both. If present in infants, myotubular myopathy causes muscle weakness, including paralysis of the eye muscles. The condition is progressive and can be severe.

Severe X-linked myotubular myopathy is a subtype of myotubular myopathy. Severe X-linked myotubular myopathy causes severe muscle weakness, resulting in difficulty swallowing and respiratory distress. The condition can be fatal.

A less debilitating form of myotubular mypathy causes symptoms to develop during the teen years or the twenties. This form of the disease is also progressive.

Nemaline Rod Myopathy

Nemaline rod myopathy causes a wide range of congenital myopathy symptoms ranging from mild to severe. Infants with mild cases of nemaline rod myopathy have non-progressive muscle weakness, while the severe form of the disease results in respiratory failure.

Congenital Myopathy Treatment

For most types of congenital myopathy, treatment is supportive, helping the individual minimize symptoms and deal with limitations caused by the disease. Medication may lessen some congenital myopathy symptoms, but cannot cure the condition.

Severe cases of congenital myopathy can cause respiratory failure in infants. Mechanical ventilation may be required to help the child breathe.

Children with congenital myopathies often have developmental delays as their muscles are weaker than normal and take longer to develop. Congenital myopathy treatment may include physical therapy, speech therapy and occupational therapy. These can help children achieve developmental milestones earlier.

The prognosis is worst for types of congenital myopathy that cause respiratory failure. Less severe congenital myopathies do not lessen life expectation significantly.

Resources

Congenital Myopathy Site. (n.d.). Types. Retrieved December 16, 2008, from the Congenital Myopathy Site Web site: http://webpages.charter.net/mccawthon/types.htm.

Merck Manuals Online Medical Library. (n.d.). Congenital myopathies. Retrieved December 15, 2008, from the Merck Manuals Online Medical Library Web site: http://www.merck.com/mmpe/sec19/ch295/ch295c.html.

Milton S. Hershey Medical Center College of Medicine. (updated 21 October, 2006). Congenital myopathies. Retrieved December 15, 2008, from the Milton S. Hersey Medical Center College of Medicine Web site: http://www.hmc.psu.edu/healthinfo/c/congenitalmyopathies.htm.