Pediatric Myasthenia Gravis
Myasthenia gravis causes weakness and rapid fatigue of the muscles over which a person normally has control.
Myasthenia gravis is an autoimmune disease that affects some nerve signals to the muscles, making them weaker. Although it can happen at any age, myasthenia gravis is extremely rare in children. Symptoms are the same in children and adults. In most cases, the neonatal form of the condition is due to an affected mother's abnormal antibodies interfering with her unborn baby's nerve impulses. Symptoms of myasthenia gravis in infants usually disappear within two to three months after birth.
In addition to muscle weakness, children with myasthenia gravis can experience:
- Change in speaking voice
- Difficulty chewing
- Difficulty swallowing or frequent choking while eating or drinking
- Double vision (diplopia)
- Drooping of one or both eyelids (ptosis)
- Reduced facial expressions
Tests and Diagnosis
The thymus gland plays a significant role in the development of a child's immune system. Although researchers don't fully understand the connection, it's generally believed that myasthenia gravis is the result of the thymus gland providing incorrect instructions to developing immune cells.
Symptoms of myasthenia gravis usually include drooping eyelids and double vision from eye misalignment. Other symptoms may include facial weakness, trouble chewing and swallowing or respiratory and/or limb fatigue. Symptoms, which vary depending on the severity of the condition, tend to improve with rest and worsen with activity.
Because muscle weakness is a symptom of several conditions, myasthenia gravis can be hard to diagnose. If a doctor suspects the condition, there are several tests available to confirm a diagnosis. They include:
- Blood tests (to detect immune molecules or acetylcholine receptor antibodies)
- Diagnostic imaging (a CT Scan or an MRI can identify problems with the thymus)
- Edrophonium test (uses edrophonium chloride to briefly relieve muscle weakness in a patient)
- Nerve conduction (repetitive nerve stimulation tests for "fatigue" in specific muscles)
- Pulmonary function testing (measures breathing strength)
- Single fiber electromyography (detects impaired nerve-to-muscle transmission)
Treatments for myasthenia gravis include medications that:
- Prevent the body from making too many abnormal antibodies, or
- Improve connections between the nerves and muscles
Other treatments may filter out abnormal antibodies or rely on donated blood to introduce healthy ones. With the right treatment, symptoms usually improve significantly or disappear completely. Myasthenia gravis may also go into remission for some children.