Myasthenia Gravis - Symptoms, Complications and Management During Pregnancy

What Is Myasthenia Gravis and How Does It Affect Pregnancy?

Myasthenia gravis (MG) is an autoimmune disorder responsible for causing weakness in the skeletal muscles (ocular, bulbar, limb, and respiratory muscles) in varying degrees and combinations. It is commonly present in women in their second and third decades of life when they are of reproductive age. Exacerbations of myasthenia gravis are more likely to happen during the first trimester and after delivery. Management of myasthenia gravis during pregnancy necessitates specialized knowledge, as both the condition and its therapy can cause adverse outcomes for the mother and the fetus.

Myasthenia has two clinical forms-

• Ocular Myasthenia Gravis (OMG)- The symptoms of ocular myasthenia gravis (OMG) are limited to the eyelids and extraocular muscles.

• Generalized Myasthenia Gravis- The ocular muscles are typically affected in generalized myasthenia gravis, although it can also affect a variety of bulbar, limb, and respiratory muscles.

Effect on Pregnancy- Females are more commonly affected by myasthenia gravis during their reproductive years. Pregnancy-related difficulties can be worrying, and the course of myasthenia gravis during pregnancy is difficult to anticipate. Patients may experience an exacerbation, a crisis, or, more interestingly, remission. Although the disease course is variable, pregnant patients are at risk of exacerbation, respiratory failure, severe drug responses, crisis, and even death.

What Are the Causes of Exacerbation of Myasthenia Gravis During Pregnancy?

Myasthenia gravis is an autoimmune disorder, its main symptom is muscle weakness. The main causes of exacerbation of myasthenia gravis during pregnancy are as follows-

• Hypoventilation due to elevation of diaphragm and weakness of respiratory muscles during pregnancy.

• Puerperal infections.

• The stress of labor and delivery.

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• Medication.

• Myasthenia gravis does not have a significant impact on pregnancy in general. There is no increased risk of low birth weight, spontaneous abortion, or prematurity in myasthenic women, yet there is an increased chance of early rupture of membranes for unknown reasons.

What Are the Symptoms of Myasthenia Gravis During Pregnancy?

• Myasthenia gravis is characterized by weak muscles. Muscles weaken with activity and recover with rest. Muscles in the eyes, face, jaw, neck, arms, legs, and breathing muscles are commonly affected.

• Pregnant women with myasthenia gravis generally experience increased weakness and fatigue. This is due to the extra weight and effort that comes with pregnancy.

• Myasthenic Crisis- A myasthenic crisis occurs when a pregnant woman becomes extremely weak and weary. They suffer respiratory failure because their breathing muscles are unable to function properly. Increased breathing issues are the most common symptom of myasthenic crisis. The pregnant woman is more prone to experience a myasthenic crisis during labor.

How Is Myasthenia Gravis Diagnosed During Pregnancy?

If myasthenia gravis is suspected, the following tests are available to confirm the diagnosis:

1. Acetylcholine Receptor Antibody Test- The presence of acetylcholine receptor antibodies can be detected using a specific blood test. These antibodies are seen in high concentrations in most myasthenia gravis patients. Antibodies, on the other hand, may not be found in 15 % of myasthenia gravis patients.

2. Repetitive Stimulation of Muscle Fibers- A repeated stimulation test is another way to confirm a diagnosis of myasthenia gravis. Repeated electrical stimuli to a nerve in the arm or face are used in this study. The response from the muscles which are stimulated by that nerve is registered. The reaction of the muscle to that neuron stimulation is recorded. The reaction of the muscle in myasthenia gravis shows signs of fatigue.

3. Edrophonium Test- The chemical edrophonium is injected into the vein to prevent the breakdown of acetylcholine. This increases the amount of acetylcholine available to the acetylcholine receptor, which may temporarily alleviate myasthenia gravis weakness.

4. Imaging- Chest computed tomography (CT) or magnetic resonance imaging (MRI) are used to interpret thymus gland abnormality or the presence of a thymoma (tumor of the thymus gland). The thymus gland is frequently malfunctioning in people with myasthenia gravis as it may instruct the immune system to generate acetylcholine receptor antibodies abnormally. Thymomas can develop in people with myasthenia gravis.

5. Other Tests-

   • Ultrasound.

   • Fetal monitoring: This is done to check for evidence of muscle weakness that could indicate myasthenia gravis in the baby.

   • Another fetal tests: The doppler flow studies are used to watch blood flow in the uterus and umbilical cord.

Getting early prenatal care and working with healthcare providers to manage the disease can have a healthy pregnancy.

What Are the Complications of Myasthenia Gravis?

Even when a person is not pregnant, myasthenia gravis can lead to a myasthenic crisis and respiratory failure. However, there are additional dangers during pregnancy. These pregnancy problems may be more common in people with myasthenia gravis-

• Preterm Labor and Difficult Delivery- A preterm labor occurs before the 37th week of pregnancy. It could be related to the medications used to treat myasthenia gravis. The muscles of the uterus are not affected by myasthenia gravis. However, the muscles required for pushing can be harmed. This may make forceps and vacuum-assisted births more likely.

• Myasthenia Gravis in a Newborn Baby (Neonatal Myasthenia Gravis)- Antibodies pass the placenta and reach the newborn. These babies may be weak, have poor suck, and have breathing difficulties. This is usually a transient condition that lasts only a few weeks.

• Magnesium sulfate should not be used by women who have myasthenia gravis. This medication is commonly used for high blood pressure and preterm labor. It inhibits nerve-muscle communication, which can exacerbate muscle weakness.

How Is Myasthenia Gravis Managed During Pregnancy?

1. Prenatal counseling and good antenatal care should be given to pregnant women.

2. Medications- Myasthenia gravis can be controlled. For symptomatic relief in myasthenia gravis, medications that inhibit the acetylcholinesterase enzyme (Pyridostigmine and Neostigmine) are the mainstay of treatment. Commonly used drugs include:

• Anticholinesterase inhibitors (Pyridostigmine and Neostigmine).

• Steroids.

• Azathioprine.

• Cyclosporine A.

• Mycophenolate, Methotrexate, and Cyclophosphamide.

• Rituximab.

• Plasma exchange or intravenous immunoglobulins.

3. Thymectomy- The surgical excision of the thymus gland is known as thymectomy. Thymectomy helps some individuals with myasthenia gravis symptoms and may even cure them, presumably by rebalancing the immune system.

4. Other Treatments- Plasmapheresis is a blood treatment that eliminates abnormal antibodies. High-dose intravenous immune globulin temporarily changes the immune system and replaces normal body antibodies with donated blood.

Conclusion:

Myasthenia gravis is a difficult autoimmune condition. It causes antibodies to damage the connections between the muscles and neurons. This results in muscle weakening and exhaustion. Myasthenia gravis is particularly dangerous during pregnancy. It can increase the likelihood of complications for both mother and the baby. Most myasthenic women can have a healthy pregnancy with no complications. Myasthenia gravis-affected pregnant women must be properly monitored. They can improve their chances of having a safe pregnancy by seeking early prenatal care and working with their doctors to control their disease.