“Myasthenia” means “muscular weakness”. According to a recent article in The Star, studies in Asia indicate that there are approximately five new cases of myasthenia gravis (MG) reported each year out of every one million people. The incidents of MG among older men appear to be on the rise.
MG is an antibody-mediated autoimmune disease. Normal communication between muscles and nerves is affected. In other words, there is an “error” in the nerve impulse transmission to the muscle.
This “error” occurs when antibodies, produced by the immune system, mistakenly prevent the neurotransmitter acetylcholine from working with its receptors. This, in turn, prevents muscle contractions and eventually leads to muscle weakness. There is currently no cure for MG.
Additional information about MG is available here.
About the Thymoma Tumor
The thymus is located behind the breastbone. It is part of the immune system. It can trigger or maintain the production of harmful antibodies.
The thymus gland is sometimes larger than normal in many MG patients. A tumor called thymoma is found in one of every ten MG patients. In the event a tumor is found, a patient is advised to have it removed. The thymoma tumors carry a high risk of invading surrounding structures.
Symptoms
The onset of MG may happen at any age. However, it most frequently affects young women between ages twenty and thirty and men between age fifty and sixty. It appears to be on the rise in older men.
Although there is no cure at present, certain currently available treatments may relieve the most common symptoms. These symptoms include weakness of limbs, double vision, and difficulty chewing, speaking, breathing and swallowing.
One of the first symptoms and one that is most indicative of MG is drooping eyelids. There are specific tests that physicians use to confirm MG.
Two Types of MG
One type of MG is called ocular myasthenia, a localized form. The second is a generalized form.
The ocular form of MG is primarily in the muscles surrounding the eyes. It is not known to spread to other muscles.
But in the generalized form, MG can spread to muscles in the shoulders, hips and to muscles that control swallowing, breathing, and speech.
Several Tests for MG
- Abnormal antibodies can be detected with a blood test searching for muscle-specific kinase antibodies and acetylcholine receptors.
- Applying ice to an upper eyelid that is abnormally lowered (drooping) for two minutes. An improvement in the lid is a sign of MG.
- Neurophysiological testing consists of recording nerve responses and electromyography which records the electrical activity of muscle tissue.
- SFEMG is the most sensitive test used to identify nerve transmission failure. It involves using a small needle around the eye area recording signals sent out by contraction of the eye muscles.
- A computed tomography (CT scan) may be recommended to check for enlargement in the thymus gland.
Medications
- Pyridostigmine tablets assist in making acetylcholine available to receptors on muscle cells.
- Steroids such as prednisolone may be recommended to improve weakness and muscle fatigue. After desired results, a lower dose is generally recommended. Caution is advised as steroids administered over a long period may cause weight gain, diabetes, acne, problems with wound healing and reduction in bone density.
Immunosuppressants may be recommended later in treatment as a substitute for steroids to avoid side effects.
Another option might be surgery which has been proven to be effective in controlling symptoms.
Thymus: Open Surgery and Keyhole Surgery
Either keyhole surgery or open surgery may be performed to remove the Thymus.
With open surgery, the breastbone is split to remove the thymus.
In order to remove the thymus using keyhole surgery, small incisions are made in the chest and neck allowing instruments and a miniature camera to be inserted for removal of the thymus.
Immunoglobulin may be administered before surgery to preclude MG from worsening.
Surgery is one of several events that can cause the MG patient to fall into a crisis mode. The other issues are infection, stress or sudden change in the patient’s treatment regimen.
Either immunoglobulin or a plasma exchange which filters blood to remove harmful antibodies are used in MG emergency situations.
Contraindications
About thirty drugs may aggravate symptoms of myasthenia gravis such as commonly prescribed antibiotics ciprofloxacin and azithromycin. Also, high blood pressure medication (beta-blockers) is on the list.
Doctors recommend patients attempt simple lifestyle changes in nutrition and sleep habits that appear to ease some of the MG symptoms. Relaxation therapy, as well as mindfulness exercises, are also beneficial.
