Myasthenia Gravis

Overview

Myasthenia gravis is a disease-causing fluctuating weakness of muscles like that of the limbs, swallowing and eye movement muscles. Myasthenia gravis (autoimmune type) happens when your body’s immune system mistakenly attacks itself. Myasthenia gravis affects how your nerves communicate with your muscles. It leads to muscle weakness that worsens throughout the day and with activity. Drooping eyelids and/or double vision are often the first sign Researchers aren’t sure why this happens. Studies suggest that certain immune system cells in your thymus gland have trouble identifying what’s a threat to your body (like bacteria or viruses) versus healthy components. A genetic changes causes congenital myasthenia. Antibodies passed from a birthing parent to a fetus during pregnancy cause neonatal myasthenia. Medications and surgery can help relieve the symptoms of this lifelong illness. Treatment includes medications that can reduce your symptoms. Monoclonal antibodies: Doctor will give intravenous (IV) or subcutaneous (SQ) infusions of biologically engineered proteins. These proteins suppress an overactive immune system, Plasma exchange (plasmapheresis): An IV connected to a machine removes harmful antibodies from your blood plasma and replaces them with donor plasma or a plasma solution. Last option is thymectomy surgery is done to remove the thymus gland.

Causes

Myasthenia gravis (autoimmune type) happens when your body’s immune system mistakenly attacks itself. Researchers aren’t sure why this happens. Studies suggest that certain immune system cells in your thymus gland have trouble identifying what’s a threat to your body (like bacteria or viruses) versus healthy components.

A genetic change causes congenital myasthenia. Antibodies passed from a birth mother to a fetus during pregnancy cause neonatal myasthenia.

Symptoms

Symptoms of myasthenia gravis may include:

Muscle weakness in your arms, hands, fingers, legs and neck.
Fatigue.
Droopy eyelids (ptosis).
Blurry or double vision.
Limited facial expressions.
Difficulty speaking, swallowing or chewing.
Trouble walking.

Initial symptoms of myasthenia gravis happen suddenly. Your muscles usually get weaker when you’re active. Muscle strength returns when you rest. The intensity of muscle weakness often changes from day to day. Most people feel strongest at the start of the day and weakest at the end of the day.

In rare instances, myasthenia gravis affects muscles in your respiratory system. You may have shortness of breath or more serious breathing problems. Contact 911 or your local emergency services number if you have trouble breathing. In general, this doesn’t occur suddenly.

Types of myasthenia gravis

The types of myasthenia gravis include:

Autoimmune myasthenia: It’s an autoimmune condition where the cause isn’t well understood but the likely cause is the production of certain types of antibodies (immune system proteins). This is the most common type.
Neonatal myasthenia: A fetus gets certain antibodies from their birth mother who has myasthenia gravis. An infant may have a weak cry or sucking reflex at birth. These temporary symptoms usually go away after three months.
Congenital myasthenia: It isn’t an autoimmune condition, and a genetic change causes this type.

There are two subtypes of autoimmune myasthenia:

Ocular: The muscles that move your eyes and eyelids weaken. Your eyelids may droop, or you may not be able to keep your eyes open. Some people have double vision. Eye weakness is often the first sign of myasthenia. Ocular myasthenia gravis may evolve into the generalized form for nearly half of all people diagnosed with this type.
Generalized: Muscle weakness affects your eye muscles and others in your face, neck, arms, legs and throat. You may find it difficult to speak or swallow, lift your arms over your head, stand up from a seated position, walk long distances and climb stairs.

Risk factors for myasthenia gravis include:

Myasthenia gravis is most common among females around age 40 and males after age 60. The condition can affect anyone at any age.

You may be more at risk of developing myasthenia gravis if you:

Have a history of other autoimmune conditions, such as rheumatoid arthritis and lupus.
Have thyroid disease.

If you have myasthenia gravis, your symptoms could trigger (start) if you:

Take medications for malaria and heart arrhythmias.
Underwent surgery.
Had an infection.

Diagnosis and Tests

Testing confirms a diagnosis. It may include:

Blood antibody tests: About 85% of people with myasthenia gravis have unusually high levels of acetylcholine receptor antibodies in their blood. Approximately 6% of people diagnosed have muscle-specific kinase (MuSK) antibodies.
Imaging scans: An MRI or CT scan can check for thymus gland problems like tumors.
Electromyography (EMG): An EMG measures the electrical activity of muscles and nerves. This test detects communication problems between nerves and muscles.