Congenital Muscular Myopathy Symptoms

Congenital myopathy is a condition that causes muscles to take an abnormally long time to relax. In people with congenital myopathy, muscle membranes contain an abnormality that makes muscles overly sensitive to any stimuli. The muscles are unable to relax quickly and remain stiff and contracted.

Muscle weakness, as well as many other symptoms, result. There are many forms of congenital myopathy. All are rare, and a few are sometimes fatal. Forms of this disease include:

• Becker Disease
• central core disease
• centronuclear myopathy
• mitochondrial myopathy
• myotonia congenital
• nemaline myopathy
• paramyotonia congenita
• Thompsen Disease.

Causes of Myopathy

Congenital myopathy is caused by a genetic defect involving a protein needed for muscles to function properly. Since it is an inherited condition, those with a family history are most at risk. Some forms of congenital myopathy are carried in dominant genes. This means that a child will be born with the disease if even just one parent has it.

Other forms of this condition are inherited recessively. If the condition is carried on a recessive gene, both parents must carry that gene for the child to be born with the disease.

With most forms of congenital myopathy, the risk of inheriting the condition is equal in males and females. There are, however, a few forms of myopathy that mostly occur in mostly in males. In these cases, mothers can carry the defective gene without having any congenital myopathy symptoms and then pass it on to their sons.

Signs and Symptoms

There are many signs and symptoms of congenital myopathy. In small children, delays can be expected in developmental milestones, and they often have problems with activities such as climbing stairs, jumping and running. Many forms of congenital myopathy also cause facial muscle weakness. Identifying signs include:

• drooping eyelids
• high arched palate
• jaw protruding past the upper portion of the face
• long narrow face.

Classic symptoms of congenital myopathy include:

• chewing and swallowing slowly
• depressed reflexes
• difficulty relaxing muscles
• difficulty releasing grip
• enlarged muscles
• hip displacement
• muscle rigidity (in general and after attempting movement)
• muscle stiffness
• muscle weakness
• overdevelopment of muscles
• strong muscle definition
• talking slowly
• walking slowly.

Diagnosing Congenital Myopathy

To diagnose congenital myopathy, the patient's family history is evaluated and a number of tests may be performed. These include:

• complete neurological exam - including testing of reflexes and strength.
• electrocardiogram (ECG)
• EMG (electromyelogram) - performed to record the electrical activity in the muscles. Thin-needle electrodes are inserted into the muscle to allow electrical activity to be either seen on a screen or heard through a speaker.
• exercise test - to see how muscles respond to exertion.
• blood tests - to measure potassium levels.
• muscle ultrasound
• nerve conduction studies (NCS electroneurograph) - to measure electrical nerve impulses. Two electrodes are taped to the skin and a mild shock is sent between them.
• provocative tests - expose patients to carbohydrates, cold, potassium and other suspected "triggers".
• serum CK (creatinine kinase) analysis
• thyroid-stimulating hormone (THS) - done to rule out other forms of myopathy.

While these tests help to determine if a patient has congenital myopathy, for a truly definitive diagnosis, genetic testing and/or muscle biopsy are usually necessary.

Resources

Adiware Pty Ltd. (2007). Symptoms of Congenital Myopathy. Retrieved January 8, 2008, from the Wrongdiagnosis.com Web site: http://www.wrongdiagnosis.com/c/congenital_myopathy/symptoms.htm#symptom_list.

Answers Corporation (2007). Congenital Myopathies. Retrieved January 8, 2008, from the Answers.com Web site: http://www.answers.com/topic/congenital-myopathies?cat=health.

Mayo Foundation for Medical Education and Research (2007). Congenital Myopathies. Diagnosis. Retrieved January 8, 2008, from the Mayoclinic.com Web site: http://www.mayoclinic.org/congenital-myopathies/diagnosis.html.

Penn State Milton S. Hershey Medical Center (2004). Congenital Myopathies. Retrieved January 8, 2008, from the Milton S. Hershey Medical Center Web site: http://www.hmc.psu.edu/healthinfo/c/congenitalmyopathies.htm.