Myasthenia gravis is an autoimmune condition affecting muscles, causing muscular weakness. Symptoms are usually worst in the face and throat. It is in this area of the body that the first symptoms are usually noticed.
What causes myasthenia gravis?
Myasthenia gravis is caused by a defect in how nerve signals are conducted from the nerve fibers to muscles. It is a disease that usually strikes men over sixty years of age and young women under forty. Sometimes myasthenia gravis, or an exacerbation of symptoms in existing myasthenia gravis, will result from incorrect drug dosage, surgery or anesthesia, or an infection.
In most myasthenia gravis patients, an abnormality of the thymus gland is found, and occasionally this is an inherited trait. In about a quarter of the patients with thymus irregularity, there is a tumor of the thymus.
What are the symptoms of myasthenia gravis?
A patient with myasthenia gravis will exhibit drooping eyelids and a general weakness of muscles in the face, and they will commonly experience double vision.
This disease does not always progress, instead symptoms usually come and go, but may become worse at times. Other symptoms may include difficulty in swallowing and breathing. The patient may experience excessive sweating, dizziness, loss of appetite, nausea, muscle spasms, extreme blurring of vision, vomiting and diarrhea.
How is myasthenia gravis diagnosed?
Since fatigue is common in so many disorders, myasthenia gravis can be a difficult diagnosis. Besides physical examination, blood tests, pulmonary function tests and imaging are done. In cases when diagnosis is difficult, drug response tests may be given.
What are the treatments for myasthenia gravis?
The myasthenia gravis patient will be given restricted physical activity and bed rest. However, there must be physical therapy to move arms and legs several times a day in order to improve range of motion. Icing can sometimes improve muscle responses.
Immunosuppressants and cholinesterase inhibitors may be given. Prior to eating, the individual is given drugs to stimulate nerve signals. If chewing and swallowing is a problem, the patient’s diet will be changed to cope with these symptoms, while maintaining the proper balance of nutrients.
When an eyelid is affected, a patch may be worn, and eye drops can be given to relieve eye discomfort and improve blurred vision.
In cases where there is a tumor found on the thymus, the thymus gland may be removed.
In extreme cases where breathing is restricted, a patient may need a machine to help them breathe.
How do you handle emergencies of myasthenia gravis?
Occasionally a crisis may arise in a patient suffering from myasthenia gravis. It is vital to know how to respond to these crises.
The patient may suddenly be unable to breathe. Usually this requires having special equipment on hand to force air into the lungs. Sometimes an emergency tracheostomy must be performed. This requires making an incision in the throat so that air can get down into the lungs.
The myasthenia gravis patient may suddenly experience high fever and flulike symptoms such as vomiting and diarrhea. It is important to get the patient to the hospital for emergency treatment as soon as possible in such cases. Sometimes antibodies must be removed from circulation through plasmapheresis, or intravenous immunoglobulin must be given.
What is the prognosis for myasthenia gravis?
Myasthenia gravis does not normally decrease a patient’s lifespan, providing the individual is receiving continuing treatment. There may be times of remission alternated with crises. In some patients, symptoms may decrease after three to five years. Quality of life will thus differ depending on the individual patient.
It is important to remember that it’s rare for the myasthenia gravis patient to get worse as time goes on, and many patients are able to enjoy their lives with supportive family and friends.
Signet/Mosby Medical Encyclopedia