Myasthenia Gravis

Causes #

Myasthenia-gravis is an autoimmune disease. For unknown reasons, the body’s immune system attacks itself.

In someone with a healthy immune system, nerves and muscles communicate a bit like a tiny baseball game:

• Nerves (the pitcher) send signals to muscles (the catcher) across a synapse (connection) called the neuromuscular junction. To communicate, nerves release a molecule called acetylcholine (the baseball).

• Muscles have sites called acetylcholine receptors (the catcher’s glove). The acetylcholine binds to the receptors in the muscle tissue, like a ball landing in a glove.

• When the acetylcholine binds to the receptor, it triggers the muscle fiber to contract.

Types #

Ocular #

The muscles that move the 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 MG. Nearly half of people with ocular MG evolve into the generalized form within two years of the first symptom.

Generalized #

Muscle weakness affects the eye and other body parts such as the 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.

Symptoms #

• Double vision.

• Drooping eyelids (ptosis).

• Difficulty speaking, chewing or swallowing.

• Difficulty moving their neck up or holding up their head.

• Limb weakness.

• Trouble walking.

Diagnosis #

Ice pack test #

If you have severely drooping eyelids, your provider may place ice packs on your eyes or have you rest with your eyes shut in a dark room for a few minutes. If the drooping improves after the ice application or rest, you may have MG.

Antibody tests #

About 85% of people with MG have unusually high levels of acetylcholine receptor antibodies in their blood. Approximately 6% patients have muscle-specific kinase (MuSK) antibodies. Antibodies may not be detected in less than 10% of MG patients.

Imaging scans #

An MRI or CT scan can check for thymus gland problems like tumors.

Electromyogram (EMG) #

An EMG measures the electrical activity of muscles and nerves. This test detects communication problems between nerves and muscles.

Complications #

• Weakness and fatigue from MG can keep you from participating in activities you enjoy.

• This may lead to depression.

• Up to one in five people with MG experience a myasthenic crisis or severe respiratory muscle weakness.

• They may need a respirator or other treatments to help them breathe.

• This is a life-threatening medical emergency. Weak muscles, infections, fevers and reactions to medications can cause a crisis.

Treatment #

Medications #

Cholinesterase inhibitors (anticholinesterase) boost signals between nerves and muscles to improve muscle strength. Immunosuppressants, including corticosteroids, decrease inflammation and reduce your body’s production of abnormal antibodies.

Monoclonal antibodies #

You receive intravenous (IV) infusions of biologically engineered proteins. These proteins suppress an overactive immune system.

IV immunoglobulin (IVIG) #

You receive IV infusions of donor antibodies over a period of two to five days. IVIG can treat myasthenia crisis as well as generalized MG.

Plasma exchange (plasmapheresis) #

An IV line removes abnormal antibodies from your blood.

Surgery #

A thymectomy is surgery to remove the thymus gland. Even if tests don’t show a problem with your thymus gland, surgical removal sometimes improves symptoms.