Myasthenia Gravis Education & Treatment
Myasthenia Gravis is a disease which should be considered anytime someone is suffering from muscle weakness of severe muscle fatigue. The symptoms can be quite varied ranging from eye drooping or double vision all the way to severe weakness of breathing muscle which would necessitate the use of a breathing machine or ventilator in order to survive. The diagnosis of myasthenia can often be very difficult and should be done by a neurologist with expertise in disease of the nerve and muscle. We at Phoenix Neurological Associates have cared for patients with mysthenia for over 25 years. Being sure that the diagnosis is correct is extremely important in myasthenia since it is always a treatable disease but the drugs used to treat myasthenia frequently have unwanted side effects. Therefore before beginning therapy one should be certain of the diagnosis
Myasthenia gravis is a disorder causing weakness and fatigue of voluntary muscles. This weakness fluctuates, with symptoms usually being less severe in the morning and then becoming worse later in the day.
It typically involves muscles closest to the torso such as shoulders and hips. This causes problems going up stairs and reaching above one’s head. It also frequently involves the muscles of the eyes. In some cases only the muscles of the eyes are affected which causes double vision and drooping eyelids. It does not affect the muscles of the heart, gut, or bladder. However the muscles of the mouth and throat can be involved which can cause severe weakness of swallowing. In severe cases the disease can involve the muscles of the diaphragm and respiratory muscles. This can lead to a patient being unable to breath without the support of a mechanical ventilator. This severe presentation of myasthenia is called a myasthenic crisis. The weakness can develop over weeks to months; however, only a minority of patients go on to have a myasthenic crisis.
Myasthenia Gravis is caused by a breakdown in the communication between nerves and muscles, usually because of an immunological problem. When the nerve sends signals to the muscles to contract a chemical called acetylcholine is released by the nerves. This chemical binds to a specific receptor on the muscle fibers called the acetylcholine receptor. In Myasthenia Gravis a person begins making antibodies against the acetylcholine receptor which destroys these receptors. Therefore the signals to move travel down the nerve but the muscle cannot respond to the acetylcholine. Rare cases of myasthenia gravis can begin in childhood or even in newborns and in these cases there is an inherited defect in part of the acetylcholine release by the nerve and the binding and response at the acetylcholine receptor.
In some cases Myasthenia Gravis can be associated with disorders of other glands including the thymus and the thyroid. All patients diagnosed with myasthenia should have tests done to look at the function of these glands.
The disease should be suspected in anyone with muscle weakness, particularly if there is drooping of the eyes or double vision. The disease is diagnosed by doing blood tests to look for antibodies against the acetylcholine receptor. A new antibody has been discovered as well called the MUSK antibody, which causes a disease identical to Myasthenia Gravis. EMG/NCS can also be performed to help confirm the diagnosis.
The treatments of this disease focus on altering one’s immune system so that fewer antibodies are produced and therefore the muscle can rebuild its acetylcholine receptors. Perhaps the most commonly used initial medication is prednisone. In addition many patients will take a medication called mestinon. Mestinon allows the remaining acetylcholine receptor a better chance to react to the acetylcholine released by the muscles. This does not treat the underlying problem but can markedly improve the Myasthenia Gravis symptoms. If prednisone does not completely resolve the muscle weakness then a variety of other drugs are used in Myasthenia Gravis treatments. Cellcept, azathioprine, cyclosporine, and intravenous immunoglobulin all have a marked chance of improving one’s disease. If patients experience a myasthenic crisis and are having difficulty swallowing or breathing, then there is a procedure called plasmaphresis which is very effective in improving one’s weakness. This is a procedure similar to dialysis in which a patient’s blood is removed and washed of their antibodies and then returned to the patient. This is usually repeated five times over a 7-10 day period and is very effective.
All patients with Myasthenia respond differently to different drugs and so the important point is to follow with a neurologist closely who can adjust medications as the symptoms dictate.
Most patients who develop myasthenia will keep the disease for the remainder of their life. There are numerous research trials and basic science research looking at how to reset the immune system and achieve a cure. In some patients if there are abnormalities of the thymus gland, then removal of this gland surgically has been associated with a chance of disease remission.
Related publications by our physicians:
Retrospective review of the safety of Hizentra in neuromuscular patients with renal failure (845k PDF)
Management of myasthenia gravis.