Myasthenia Gravis (MG) Serum Samples

Also, MG is a neuromuscular disorder that causes weakness in the skeletal muscles, which are the muscles your body uses for movement. 

In fact, myasthenia gravis occurs when communication between nerve cells and muscles becomes impaired.

This impairment prevents crucial muscle contractions from occurring, causing muscle weakness.

According to the Myasthenia Gravis Foundation of America, more than 70,000 people in the United States have received a diagnosis of myasthenia gravis.

Fast Facts on Myasthenia Gravis (MG)

• Myasthenia gravis (MG) is a chronic autoimmune disorder in which antibodies destroy the communication between nerves and muscle.
• Myasthenia gravis affects the voluntary muscles of the body, especially those that control the eyes, mouth, throat and limbs.
• The disease can strike anyone at any age, but is more frequently seen in young women (age 20 and 30) and men aged 50 and older.
• A myasthenia gravis crisis can involve difficulty in swallowing or breathing.
• The cause of myasthenia gravis is unknown and there is no cure, but early detection and prompt medical management can help people live longer, more functional lives.

The causes and risk factors can include:

An Autoimmune Reaction

Autoimmune disorders occur when your immune system mistakenly targets healthy tissue. In MG, these antibodies, which usually target harmful substances in the body, instead damage nerve cells.

The antibodies block or attack acetylcholine receptors, which makes muscles unable to respond to acetylcholine and contract. This results in muscle weakness.

The exact cause of this autoimmune reaction is unclear. The MDA suggests specific viral or bacterial proteins may prompt the body to target acetylcholine.

A family history of autoimmune diseases may increase your risk of developing an autoimmune disorder like MG.

Thymus Gland Irregularities

The thymus gland typically grows until puberty and controls healthy immune functions throughout your life. After puberty, the gland shrinks in size.

In many people with MG, the thymus gland stays large.

Developing benign or cancerous thymus gland tumors is also possible, which may interfere with crucial immune cell production. The enlarged thymus gland also produces antibodies that block acetylcholine.

About 75% of people with MG have thymus gland irregularities (thymic hyperplasia), and another 15% have tumors.

As a result, the thymus gland may give your immune system incorrect instructions, which researchers believe may lead to immune cell destruction that causes MG.

Age

While MG may develop at any age, the NINDS notes that females are more likely to receive a diagnosis before age 40, whereas males are more likely to receive one at 60 or older.

About 10-15% of MG cases develop in childhood.

It’s also possible for newborn babies to have a temporary condition called neonatal myasthenia. This occurs when the mother has MG and passes the antibodies to a fetus. However, neonatal myasthenia is different from MG. It is temporary, lasting about 2-3 months post-delivery.

The main symptom of MG is weakness in the voluntary skeletal muscles, which are muscles under your control.

In fact, muscles typically fail to contract if they can’t respond to nerve impulses. When communication between nerve and muscle is blocked, weakness results.

Although, the degree of weakness can change daily, and symptom severity typically increases over time if left untreated.

Also, weakness associated with MG usually gets worse with activity and improves with rest.

Consequently, patients with MG may experience different symptoms affecting different parts of the body, such as:

Eyes

When affecting the eyes, MG can cause:

• Drooping eyelids (ptosis)
• Blurry or double vision (diplopia)
• Problems with eye and eyelid movement

Face

MG can affect your control of your facial muscles. This can cause:

• Changes in your facial expressions
• Difficulties chewing
• Facial paralysis

Throat

When MG affects the muscles of the throat, the patient may experience:

• Difficulty speaking (dysarthria)
• Issues with swallowing (dysphagia)
• Problems with chewing
• Hoarse voice
• Neck weakness, which can make it difficult to hold up your head

Chest

When MG affects the muscles of the chest area, the patient may experience

• Difficulty breathing
• Shortness of breath
• Weakness in the diaphragm and chest muscles

Also, this can lead to myasthenic crisis and  respiratory failure.

In fact, a myasthenic crisis is life threatening and requires emergency medical treatment.

Arms and legs

MG can also affect muscles in the arms and legs, which may cause:

• Fatigue
• Overall weakness in your legs
• Problems walking up stairs or lifting objects
• Weakness in your fingers, hands, and arms

A doctor typically performs a complete physical exam and takes a detailed history of the patients symptoms. They’ll also do a neurological exam.

As this may consist of the following:

• Checking your reflexes
• Looking for muscle weakness
• Checking for muscle tone
• Seeing how your eyes move
• Testing sensation in different areas of your body
• Evaluating motor functions, like touching your finger to your nose

Also, other tests that can help diagnose the condition include:

• An edrophonium (Tensilon) test
• Blood testing for antibodies associated with MG
• Imaging using CT scans or MRI to rule out a tumor
• Repetitive nerve stimulation and single-fiber EMG tests

You may want to talk with a doctor if you have unusual symptoms affecting your eyes, face, throat, or overall body movements. You should be especially aware of possible MG symptoms if you’re an older adult with a personal or family history of autoimmune disorders.

If you have MG, you may go into remission, or a period where your symptoms may get better or go away. However, since remission may be temporary, it’s important to keep track of your symptoms and talk with a doctor if they return.

Treatment of Myasthenia Gravis (MG)

Currently there is no cure for MG. Treatment involves managing symptoms and controlling the activity of your immune system. Treatment options can include:

Thymus Gland Removal

Doctors may recommend removing the thymus gland (thymectomy) in many people with MG. Doctors also recommend surgery to remove thymus gland tumors, even benign ones, as they may become cancerous.

Once the thymus is removed, patients typically show less muscle weakness. Research from 2017 also shows that thymectomy and  prednisone may be more effective than taking prednisone alone.

The long-term outlook for MG depends on a lot of factors. Some people will only have mild symptoms, while others may have more severe ones. Remission is also possible.

Early and proper treatment can help limit disease progression and improve quality of life.