Myasthenia Gravis

Myasthenia gravis is an autoimmune disease that causes the muscles, especially in the eyes, mouth, throat, and limbs, to weaken after periods of activity. The weakness usually improves after a period of rest. When this condition occurs in children, it’s called juvenile myasthenia gravis (JMG).

Most children with JMG have symptoms that come and go throughout their lives. The degree of muscle weakness and the muscles that are affected vary from person to person. In some cases, JMG may be a life-threatening condition. However, with treatment, most children with the disease improve over time and some children go into remission (symptom-free periods) for long periods of time.

The most common symptom of myasthenia gravis is muscle weakness that gets worse later in the day or after a period of activity.

Other common symptoms can include:

• Drooping eyelids or double vision
• Difficulty speaking
• Difficulty swallowing
• Fatigue
• Weak neck muscles
• Problems walking
• Lopsided facial expressions

Every person with myasthenia gravis doesn’t have all of these symptoms, and the symptoms can change over time.

The symptoms of myasthenia gravis can get worse from:

• Alcohol use
• Fatigue or lack of sleep
• Taking certain medications, including penicillamine, interferons, certain antibiotics, and cardiovascular drugs

It is not known why certain people develop myasthenia gravis. It is not a condition that is passed down in families.

The first step in diagnosing this condition is a physical exam, during which your child's clinician will take your child’s complete medical history and may ask about your family history.

The clinician may also order one or more of the following tests:

• Antibody titer tests to see if antibodies are attacking your child’s neuromuscular system. If these tests are positive, it is likely that your child has myasthenia gravis.
• Repetitive nerve stimulation is another way of diagnosing the condition. It is performed during an electromyography study (EMG) and involves stimulating specific nerves and examining abnormal muscle movements.
• Tensilon tests are sometimes used to confirm a diagnosis of myasthenia gravis. During this test, your child will get an injection of a small amount of a medicine called Tensilon. If your child has myasthenia gravis, there will be an immediate, brief increase in muscle tone.
• Stimulated single fiber EMG (SSFEMG) is a specialized test that is also performed in the EMG laboratory. It is sometimes used when other tests are negative or inconclusive.

Although myasthenia gravis can't be cured, there are several treatment options that can help strengthen muscles, manage symptoms, and prolong symptom-free periods.

Depending on your child’s specific needs, he or she may receive one or more types of treatment.

Medications

Several types of medications are used to help reduce the symptoms of myasthenia gravis.

• Acetylcholinesterase inhibitors: These medications work well for some children with mild symptoms.
• Immunomodulatory therapy: These medications help reduce the quantity of harmful antibodies in the body. They may include plasmapheresis, intravenous immunoglobin (IVIG), and steroids.

Surgery

Children whose symptoms don’t improve with medication, or those who are heavily dependent on medication, may benefit from a surgery called thymectomy. This is the removal of the thymus, a gland in the chest that has been linked with production of the harmful antibodies.

This procedure can work very well in some, though not all, cases. Some children who have this surgery do have significant improvement.

Our staff at the Boston Children's Hospital Neuromuscular Center is dedicated to treating children with myasthenia gravis and developing the best treatment plans to manage this condition. Our team of world-renowned experts in child neurology, orthopedics, genetics, and ophthalmology treat a wide range of rare disorders, including myasthenia gravis.

We use the most advanced diagnostic and treatment methods available and incorporate minimally invasive techniques whenever possible. Our teams will work together with your family to develop treatment plans that meet your child's unique needs.