Myasthenia Gravis

Originally my main association with this condition was that I remembered Jackie Kennedy's second husband, Aristotle Onassis, had it. I had a vague recollection of reading that he had to have his eyes taped open so that he could see, so I knew it had something to do with your eyelids drooping, but I had never really studied it.

About three years ago I started to notice that in pictures my right eye seemed smaller than my left eye. And I started to realize that my right eyelid had started to droop. Now I always had rather heavy eyelids - "bedroom eyes" as my mother used to tell me they were called, when she was trying to make me feel better about them. But this was something new. I looked at old pictures, trying to decide if it had always been that way. I didn't see evidence of it going back to my younger days.

I knew it was an actual problem when a friend of mine at work pointed it out, asking if I realized my eyelid was drooping. This was serious; not only was it drooping, and I didn't know why, but it was also - horrors - a cosmetic issue! People could notice it! It wasn't just me being paranoid!

I started Googling myasthenia gravis. Naturally I found it could be a serious illness; it wasn't necessarily just droopy eyelids. It could lead to generalized weakness and could even be fatal. Ah, a perfect disease for a hypochondriac. Hypochondriacs need to not only fear that they have a disease, but that that disease is serious, and preferably life-threatening. (Actually, nowadays treatments are very effective, so MG is not all that dangerous anymore).

Some people would have gone to the eye doctor first. Not me. I called up the neurologist that we'd taken my father to when he started to develop dementia. I made an appointment and went to see him. He agreed my right eyelid was kind of droopy and scheduled me for a special test that they do in the hospital (on an outpatient basis). Basically MG is caused by a lack of a certain chemical, and the way the test works, they give you an infusion of something else that increases the level of this chemical and see if your eyelid springs open suddenly. I sat there waiting as they injected the IV. I felt a slight twitch of my eyelid but no change was seen. Apparently I didn't have Myasthenia Gravis.

So then I went to the eye doctor, who told me that many times as people age (I hate that, why is it everything going wrong with me is from "aging"?) the muscles holding up the eyelids often loosen up and need to be tightened up surgically. Since it wasn't bothering me that much I didn't pursue it, but now three years later I'm noticing that it's harder to see out of the right eye and I think I may address the problem this year.

In the meantime, I will share with you all the knowledge I have learned about myasthenia gravis in the course of my experience with the possibility of having it.

What is Myasthenia Gravis?

Literally, taken from both Greek and Latin, it means "grave muscle weakness" - a pretty descriptive title.

Myasthenia gravis is a "chronic autoimmune neuromuscular disease characterized by varying degrees of weakness of the skeletal (voluntary) muscles of the body." (taken from this website:
http://www.ninds.nih.gov/disorders/myasthenia_gravis/detail_myasthenia_gravis.htm

What this means in plain English is, the body actually starts attacking its own cells and causes muscle weakness. This weakness increases during activity and improves after rest. The muscles that control eye and eyelid movement, facial expression, chewing, talking, and swallowing are often affected. The muscles that control breathing and neck and movements of the arms and legs can also be involved.

The way the muscles usually work is, nerve impulses stimulate the muscles by releasing a chemical called acetylcholine, a "neurotransmitter." Acetylcholine then binds to receptors that then cause the muscle to contract. In myasthenia gravis, the body's own immune system starts making antibodies that attack the receptor cells and disrupt the signal from the nerves to the muscles. As a result, the muscles aren't able to contract as they usually would.

It is believed that the thymus gland plays a role in myasthenia gravis. This gland, which is found in the upper chest area, is part of the body's immune system. The gland is larger when you are a baby; it shrinks when you become an adult. But, in some adults with myasthenia gravis, the thymus is abnormally large and has an overgrowth of certain cells. Some people also have tumors of the thymus, called "thymomas." Usually, thymus gland tumors are noncancerous. Scientists are still unsure of the exact role that the thymus plays in the condition.

Some factors can make myasthenia gravis worse, including fatigue, illness, stress, extreme heat, and some medications, such as beta blockers, calcium channel blockers, quinine and some antibiotics.

What are the symptoms?

In many cases, the first sign of the disease is, as I correctly remembered, weakness of the eyelids, making them droop (called "ptosis"). In some cases, the condition is limited to the eyelids alone, which is called "ocular myasthenia gravis." However, in other cases, MG causes a general effect over the body, and other symptoms can include:

-Facial muscle weakness causing change in facial expression;
-Double vision;
-Difficulty in breathing, talking, chewing or swallowing;
-Muscle weakness in your arms or legs;
-Fatigue brought on by repetitive motions (the more times you use a muscle the weaker it gets).

Not all days will be the same; some days a myasthenia gravis patient will feel better, other days he or she will feel worse. Temporary remissions may occur.

How is it diagnosed?

There are a number of ways to find out whether or not you have myasthenia gravis. The first would be a simple neurological examination, where the doctor tests your reflexes, muscle strength, ability to walk, your balance and coordination.

Another test is a blood test that looks for special antibodies that are the culprits attacking the acetylcholine receptors. However, not all cases can be diagnosed this way since these antibodies don't alway show up in the ocular type of myasthenia gravis.

Another test is called the "edrophonium test." Although I had also had the neurological exam and the blood test, this was the test that my doctor decided ruled out MG in my case. As I mentioned above, the doctor gives an intravenous dose of a chemical called edrophonium chloride or Tensilon(r), which temporarily increases the levels of acetylcholine at the junction between the nerves and the muscles. If the person has myasthenia gravis affecting the eye muscles, the Tensilon(r) will briefly relieve weakness and cause the eyelids to raise.

Doctors also do a study which tests for specific muscle "fatigue" by repetitive nerve stimulation.

Another common test for myasthenia gravis is single fiber electromyography (called EMG), in which single muscle fibers are stimulated by electrical impulses. Muscle fibers in myasthenia gravis do not respond as well to repeated electrical stimulation compared to muscles of normal individuals.

The doctor may also do a CT scan to see whether the patient has an abnormal thymus gland or a tumor of the thymus.

Pulmonary function testing may also be used to test the breathing strength.

How is it treated?

The good news is, there are a number of effective treatments for myasthenia gravis.

Medications include the cholinesterase inhibitors, such as pyridostigmine (Mestinon) and neostigmine (Prostigmin. These drugs help communication between the nerves and muscles, improving muscle contraction and strength.

Drugs such as prednisone, cyclosporine, and azathioprine, which suppress the immune system, can also help. These medications improve muscle strength by suppressing the production of abnormal antibodies. They may cause major side effects such as bone thinning, weight gain, diabetes, increased risk of some infections and a redistribution of body fat. Anyone who has ever temporarily taken prednisone for a bad case of poison ivy or some more serious ailment knows the "moon face" look that they get from these drugs. Longer term, fat can be deposited in other places as well.

In some cases, the doctor may surgically remove the thymus gland. Removal of the gland reduces symptoms in many cases and can be curative. This treatment is usually recommended for younger patients under 60.

Some patients who are severely affected by MG are given a treatment called plasmapheresis, where the blood is filtered and the antibodies affecting the acetylcholine receptors are removed. This is not a permanent cure since antibodies re-form, but it can help temporarily.

Intravenous immune globulin, which temporarily provides the body with normal antibodies from donated blood, is sometimes given during periods of weakness.

Sometimes a life-threatening situation, called a myasthenic crisis, occurs when the muscles that control breathing weaken severely, requiring a respirator for assisted breathing. These crises may be triggered by infection, fever, or a reaction to medication.

Generally the prognosis is good for myasthenia gravis sufferers. With all of the treatments available, they can expect to live a normal lifespan with good quality of life.

Research continues and it is likely that more new treatments will be developed as understanding of this condition continues to increase.

Will you get it?

Probably not; lifetime risk is 500 in a million, or about 0.1%, if my math serves me. Annually, between 2.5 and 20 people per million get this disease.

Myasthenia gravis more commonly affects young adult women (under 40) and older men (over 60), but it can occur at any age. Any ethnic group can get it.

In neonatal myasthenia, the fetus may acquire antibodies from a mother affected with myasthenia gravis. Generally, cases of neonatal myasthenia gravis are temporary, and the child's symptoms usually disappear within 2-3 months after birth. Other children develop myasthenia gravis indistinguishable from adults.

Myasthenia gravis is not directly inherited and is not contagious, so you don't have to worry about catching it from anybody. However, the disease may occasionally occur in more than one member of the same family.

This post is based on information from the website posted above, plus the following links:
http://www.neuro.wustl.edu/neuromuscular/mtime/mghxpe.html
http://www.mayoclinic.com/health/myasthenia-gravis/DS00375/DSECTION=3