Myasthenia gravis or MG is a neuromuscular disorder that makes the skeletal muscles feel weak. The skeletal muscles are those muscles in your body that are used mainly for movement. The condition happens when the communication between the muscles and the nerve cells is impaired. The impairment is what’s preventing the most crucial muscles in the body from developing, thereby causing the muscles to feel weak.
As stated by the Myasthenia Gravis Foundation in America, the Myasthenia Gravis is one of the most common primary disorders in terms of neuromuscular transmission. The condition is relatively rare affecting 14 to 20 in every 100,000 people in the US.
Myasthenia Gravis Symptoms
Weakness in the voluntary skeletal muscles is the main symptom of Myasthenia gravis. These are muscles that are totally under your control and failure of the muscles to contract is mainly because they are not able to respond on nerve impulses. Without the correct transmission of the impulse, communication in between the muscles and the nerve is blocked, which explains the weakness of the muscles.
Weakness associated with Myasthenia gravis could get worse as you become more active and will only improve when you’re at rest. Below are some of the most common symptoms of MG:
- Difficulty in breathing because of the weakness of the muscles
- Difficulty in chewing or swallowing
- Double vision
- Drooping of the eyelids
- Facial paralysis
- Fatigue
- Hoarse voice
- Problems when walking up the stairs or when lifting objects
- Trouble with talking
Not everyone will suffer from every symptom and the level of muscle weakness would vary daily. Moreover, the severity of the symptoms would normally increase over time if it’s left untreated.
What Causes Myasthenia Gravis?
Myasthenia gravis is mainly due to an error in the communication of the nerve impulses towards the muscles. This happens if a normal communication in between the nerves and the muscles is interrupted in the neuromuscular junction, as this is the place where the nerve cells would connect with the muscles that they are controlling.
Neurotransmitters refer to those chemicals, which the brain cells or the neurons would use in sending out information. Normally, once the impulses or electrical signals would travel down into a motor nerve, nerve endings would end up releasing a neurotransmitter known as the acetylcholine. This neurotransmitter would travel from the nerve endings and will combine with the acetylcholine receptors of the muscles. The acetylcholine’s binding to the receptor will trigger the muscle to activate and cause a contraction.
If you have been diagnosed with MG, the antibodies would block, alter, and destroy the receivers of the acetylcholine within the neuromuscular junction. As a result, the muscles will be prevented from contracting. For most individuals suffering from MG, the antibodies of the acetylcholine receptor are causing the condition. However, antibodies to some other proteins, such as the Muscle-Specific Kinase or the MuSK protein may also trigger the impairment of the transmission within the neuromuscular junction.
The immune system of the body would produce these antibodies. Myasthenia gravis is considered an autoimmune disease simply because the immune system will end up mistakenly attacking itself. The immune system is supposed to be the one protecting the body against foreign objects.
The thymus is a gland responsible for controlling the immune function and is also linked to MG. This gland is located at the chest right behind the breastbone. The thymus is usually the largest gland among children and grows gradually until such time that they reach the puberty stage. At this point, the thymus becomes smaller and will be replaced by fats.
All throughout the childhood, thymus plays an important role in the development of the body’s immune system since it’s responsible for producing the T cells, a type of white blood cell that’s capable of protecting the body against infections and viruses.
For most adults suffering from myasthenia gravis, their thymus glands remain large. Those with the condition will normally have clusters of immune cells within their thymus gland, which is similar to the lymphoid hyperplasia. This is a condition that happens in the spleen as well as the lymph nodes during the active immune response.
The thymus gland also plays an important role in MG; however, its function is not yet fully understood. Some researchers believe that the thymus gland is responsible for providing incorrect information to the developing immune cells, which is what’s causing the immune system to trigger an attack in its own tissues and cells, producing the acetylcholine receptor antibodies and then setting the stage for an attack on the neuromuscular transmission.
Who Gets Myasthenia Gravis?
MG is a condition that affects both men and women, regardless of the race and ethnicity. It commonly impacts the young adult women who are less than 40 years old and affects older men who are more than 60 years old. However, the condition could also occur at any age, even during childhood.
Myasthenia gravis is a condition that is not contagious and it’s not inherited as well. There are also instances that the condition could occur in more than one member of a family.
Although MG is rarely seen among infants, the fetus could acquire the antibodies from the affected mother. This condition is known as the neonatal myasthenia. In most cases, the neonatal myasthenia gravis is just temporary and the symptoms will eventually disappear after two to three month since birth. But in rare cases, babies of healthy mothers may also develop the congenital myasthenia.
How is Myasthenia Gravis Diagnosed?
Your physician will ask you to undergo a complete physical exam in order to diagnose MG. A detailed history of the symptoms will also be determined and a neurological exam may be performed. The diagnosis will usually include the following:
- Checking the muscle tone
- Checking your reflexes
- Looking at your muscle closely for weakness
- Making sure that your eyes are able to move properly
- Testing the motor functions, such as touching your finger to your nose
- Testing the sensation of the different areas of your body
Here are some other tests that your doctor may perform in order to diagnose the condition:
- Blood testing for antibodies that are linked to MG
- Edrophonium (Tensilon) test. This makes use of a drug called Tensilon, a placebo that will be administered intravenously. You will then be asked to undergo muscle movements while being observed by your physician.
- Imaging of the chest through MRI or CT scans to check for the presence of a tumor.
- Repetitive nerve stimulation test
What is a Myasthenic Crisis?
The myasthenic crisis is a medical emergency that happens when the muscles that are responsible for controlling your breathing will be weakened to the point that individuals will need to use a ventilator to help them in breathing.
There’s approximately 15 to 20 percent of people who have myasthenia gravis that experiences the myasthenic crisis. This condition requires immediate medical attention, which is usually triggered by stress, infection, surgery, or as an adverse reaction to a medication.
Treatment Options
There is really no treatment for Myasthenia Gravis, but there are treatments that can help to manage the symptoms and control the immune system’s activity.
Medication. Immunosuppressant and Corticosteroids are often used in suppressing the immune system. These medications can help to lessen the abnormal immune response that usually occurs to those with MG.
In addition, the cholinesterase inhibitors, like the Pyridostigmine can also be used in improving the communication in between the muscles and nerves.
Thymus Gland Removal. Removing the thymus gland, which is usually part of the immune system, may be a more appropriate cure for some patients suffering from MG. As soon as the thymus is removed, patients will eventually show less weakness in their muscles.
As stated by the Myasthenia Gravis Foundation, about 10 to 15% of those with MG may have a tumor within their thymus. These tumors, including the benign, must be removed since they could become cancerous.
Plasma Exchange. Also known as the plasma exchange, the Plasmapheresis is a process that takes away the harmful antibodies from blood and could result in the improvement of the muscles’ strength. This treatment is usually short term because the body will continuously produce harmful antibodies and thus, weakness could recur. Plasma exchange is highly recommended before surgery or during those times when the patient would suffer from extreme weakness.
Intravenous Immune Globulin. The IVIG or the Intravenous immune globulin is a blood product given by donors. Although it’s not yet known how this works, it could affect the development and functionality of the antibodies.
Lifestyle Changes
There are certain things that you can do at home in order to alleviate the symptoms of MG:
- Avoid stress and exposure to heat as these could worsen the symptoms.
- Get as much rest as you can to minimize the weakness of your muscles.
- If you are suffering from double vision, discuss this with your doctor and see if you need to wear an eyepatch.
These treatments may not be able to fully treat you of your MG but these should help to lessen the symptoms. Some patients might go into remission, and during which, treatment may no longer be necessary.
Make sure you inform your doctor about any supplements or medications that you are currently taking. There are certain drugs that could make the symptoms of your MG worse. But before you decide to take any new medication, talk to your doctor and make sure that it is safe for you.
What is the Prognosis?
When it comes to treatment, a lot of the patients would show some significant improvement on the weakness of their muscles and could go on with their normal lives. But there are instances when the severe weakness of the MG could lead to the failure of the respiratory and in this case, emergency medical care may be needed.
There are some patients who may go into remission, temporarily or permanently. The muscle weakness could completely disappear, and thus, medications could be possibly discontinued. Stable and long-lasting remission is often the main goal of thymectomy and could occur in 50% of those who have gone through the procedure.
Myasthenia Gravis Complications
The complications as a result of myasthenia gravis can be treated. However, others are also life-threatening:
Thymus Tumors. Almost 15% of those with MG may have some tumor growing in their thymus. This is a gland just below the breastbone and is involved with the body’s immune system. Most of the tumors, known as the thymomas, are not really cancerous.
Myasthenic Crisis. Myasthenic crisis is usually a life-threatening situation, which happens when the muscles responsible for controlling the breathing could become very weak and won’t be able to function well. Emergency treatment may be required to provide mechanical assistance.
Other Disorders
People who have MG could end up suffering from the following:
Autoimmune Conditions. Those who have myasthenia gravis are more likely to develop some other autoimmune conditions, like lupus or rheumatoid arthritis.
Overactive or Underactive thyroid. Thyroid gland would secrete hormones that could normalize your level of metabolism. If your thyroid is not active, you could suffer from the difficulties in dealing with cold, managing your weight, and some other issues. On the other hand, overactive thyroid could also make one to suffer from the difficulties in dealing with weight loss, heat, and some other issues.
What Research is Being Done?
The main goal of the NINDS or the National Institute of Neurological Disorders and Stroke is to search for fundamental knowledge regarding the brain and the nervous system and use such knowledge in minimizing the burden brought about by these neurological diseases.
Although there’s not yet a cure for the Myasthenia Gravis, the manner in which the disorder is managed has greatly improved in the past 30 years. There has been a greater understanding of the overall functionality and the structure of neuromuscular junction, which is the fundamental aspects of the thymus gland and of the autoimmunity, including the disorder itself.
Various technological advances have also led to a more accurate and timely diagnosis of MG and several new and enhanced therapies have greatly improved. Several researchers are currently working to create better medications and are looking for new ways on how the condition can be diagnosed and treated.
Special Concerns for MG Patients
Maintaining a healthy weight is not easy and if you’re weak because of MG, exercising can be such a challenge. Furthermore, if you are taking medications like prednisone, you could expose to gain some extra weight. Yet doing everyday activities with the extra weight could easily drain your strength. So try to keep your weight in check as it’s definitely worth all the effort.
It’s important to prevent osteoporosis, which normally happens with age. As stated by the National Osteoporosis Foundation, those who are below 50 years old should consume 1,000 mg of calcium and as much as 800 IU of vitamin D every day. Drinking up to 8 ounce of milk that has 300 mg of calcium should be enough.
Diet for Myasthenia
The food that you eat will have an impact on the overall functioning of your immune system. If you’re suffering from MG, which is an autoimmune condition, avoiding a certain type of foods can prevent the irritation of your immune system. You should eat foods that could contribute to the better functioning of your immune system. A diet that encourages the proper functioning of your immune system can greatly help to ease the symptoms and may lead to remission.
How to Reduce Immune System Irritation
Health experts recommend cutting back on foods that would trigger inflammation in the body as these foods could promote harmful autoimmune response. Among the foods that could trigger inflammation are animal proteins, and those that contain trans fats, as well as polyunsaturated oils like sunflower oil, and corn oil. Foods made of white flour and those that are rich in table sugar, such as candy and cakes could also irritate your immune system.
How to Ease Inflammation
Since inflammation could trigger an autoimmune response, you should focus on eating only those foods that could help to ease inflammation while avoiding those that could worsen it. Some of the best choices are good fats found in canola oil and olive oil, as well as foods that are rich in Omega 3 fatty acids, such as walnuts, flaxseed, and fatty fish. You should also eat plenty of vegetables and fruits, as these foods are the richest sources of antioxidants. These nutrients can help to prevent cell damage, promote the healthy immune system and ease the inflammation.
Importance of Potassium
Having a low level of potassium can also lead to fatigue, which is a common problem for those suffering from MG. You should eat foods that contain a good amount of potassium in order to make sure that you have an adequate amount of stored potassium in your body. Some of the potassium-rich foods are bananas, lean meats, low-fat dairy, fish, turkey, and some fruits and vegetables.
Eating for Your Condition
The Myasthenic Association of Australia has recommended eating small meals all throughout the day instead of devouring three large meals. Doing so can help to reduce the fatigue that comes with this condition. If possible, avoid eating foods that will require you to chew a lot. Crumbly foods must also be avoided since they could get stuck in your throat and will increase your chances of choking.
Considerations
Since MG is a type of condition that could affect your ability to eat, you could end up with inadequate nutrition. You may want to work with a dietitian and some other qualified healthcare professionals to help you in coming up with an eating plan that could maximize your consumption of vital nutrients. Your dietitian may design a suitable eating plan for you while taking into account your preferences.
Is Myasthenia Gravis a Disability?
Disabling Symptoms of Myasthenia Gravis
Some of the first sights of MG are difficulty swallowing, slurred speech, as well as the weakness of the eye muscles.
The weakness of facial muscles could also trigger a loss of control over the eyelid movement. This can also lead to double vision, drooping of one eye, and a difficulty in making a facial expression. It could also lead to problems in chewing and talking properly. The weakness of the muscles in the chest and neck may also lead to the inability to swallow, difficulty in breathing, and weakness of the neck.
In some cases, those with Myasthenia Gravis may end up in myasthenic crisis, a condition that occurs if the respiratory muscles get paralyzed. When this happens, the patient may need to be attached to breathing machines.
When You Can Get Disability Because of Myasthenia Gravis
Sometimes, MG can be fairly mild and can be possibly controlled with medication. It could also progress quickly to a disabling state. When the condition starts to affect your muscles that you can no longer perform some tasks, there are two ways on how you can be approved with Social Security benefits: First, you have met the requirements for the disability listing of Myasthenia Gravis to get automatic approval and second, the Social Security has agreed that MG is indeed affecting the functioning of your muscles that you are unable to work because of the substantial pain.
Meeting the Myasthenia Gravis Listing
There is a specific disability listing for Myasthenia Gravis in Social Security. It lists down situations that you could qualify for disability benefits. Social Security has changed the listing in 2016. In order to qualify for the disability, you must be able to prove that you did have MG through the following:
- Inability to control the movement of at least two of your extremities, which renders you unable to balance when walking or standing.
- Weakness at the bulbar muscles, which results in your need for parenteral or enteral nutrition or myasthenic crisis that requires mechanical ventilation.
- You will be “marked” as having physical problems with a “limitation” under any of the following: Finishing tasks (inability to concentrate, etc.), Interact with others (social problems), Thinking (ability to understand, remember, and apply information)
Proving that you’re suffering from MG can be difficult since the muscles are often at rest and will not generally have a significantly notable weakness. It is for this reason why it’s important that your doctor will consider your muscles as fatigued during testing and will record your muscles’ progressive weakness.
Moreover, some patients suffering from MG may have long periods of remission followed by exacerbations. However, Social Security is very much away that MG is an episodic condition so they will consider the duration and the frequency of the exacerbation and the length of remission period.
Medical evidence that can be used to satisfy the requirements of the listing is the electrical impulse machine. This machine is used to stimulate muscles in order to evaluate its weakness. The patient may also be asked to undergo pulmonary function tests to measure breathing, as well as physical exams that include leg raises, strength tests, and endurance tests.
Loss of Ability to Do Gainful Work
Some patients suffering from MG may not meet the criteria provided in the listing above since they have no issues with swallowing and talking or that the doctor has not found any weakness in their legs or arms, which the Social Security may consider as being significant enough. Nevertheless, these patients may have certain limitations that could prevent them from returning to work and to earn enough money per month.
Social Security may also need to go through your medical records to check the limitations that your doctor has identified and will include them in your RFC or Residual Functional Capacity assessment. Your RFC will identify the particular work activities and jobs that you’re only capable of doing if there are any.
Epidemiology
Even though the Myasthenia Gravis is a rare condition, the prevalence rate of this condition has greatly increased recently and this may be likely due to the improvement of the diagnosis as well as the treatment. The recent prevalence rates have reached 20/100,000 and a wide range of incidences is reported to an estimated 2 to 10.4 million every year in Virginia, while 21.27 million per year in the city of Barcelona.
The onset of Myasthenia Gravis is often influenced by gender and age through a bimodal fashion. Women predominate among patients who are below 40 years old having a ratio of 7:3. During the 5th decade, several new cases of MG have been distributed evenly among men and women. After they reach the age of 50, new cases of the condition are often more common among men having a ratio of 3:2.
On the other hand, pediatric cases of MG tend to be very rare. Juvenile Myasthenia Gravis is considered an autoimmune disorder and congenital MG is often a result of a genetic mutation that could damage the neuromuscular transmission. The transient neonatal MG is seen as a self-limited disorder that is linked to the placental antibody transfer coming from mothers who are suffering from MG.
Clinical Description
In Myasthenia Gravis, patients often present fatigable and fluctuating weakness of a particular muscle group and not merely a generalized pain or fatigue. The weakness that the patient would feel would vary although it generally gets worse later in the day. Increased body temperature and sustained exercise could increase the level of weakness. The ocular weakness that comes with asymmetric ptosis, as well as binocular diplopia, is often the most common upon initial presentation.
The ocular weakness can be seen as fatigable and fluctuating and would sometimes alternate the binocular and ptosis diplopia that would revolve during the closing and the covering of one eye. Some patients also complain about difficulty in reading, driving, and when watching television. Bright lights tend to be a bit bothersome. In retrospect, so many patients complain of periods of blurry vision before they can even discern dual visual images.
The examination requires demonstrating the asymmetrical weakness of the various extra-ocular muscles, which is not attributed to single cranial neuropathy. The Pupillary function is considered normal and ptosis may be elicited. In Myasthenia Gravis, ptosis is asymmetrical in general and may be due to the contraction of ipsilateral frontalis muscle in order to compensate for the weak muscles. Excessive elevation of the lid, also known as Cogan’s lid, may twitch and sign may be observed if gaze is directed from downwards to upward.
Muscles of the jaw closures may also be affected frequently for patients suffering from Myasthenia Gravis, although strength is just normal during the opening of the jaw muscles. Patients may also be complaining about a difficulty in chewing tough foods and others may choose to alter their diet in order to compensate for such difficulty. Some patients will find a thoughtful resting posture and would place their thumb beneath their chin so as to keep their jaws closed. The closure of the jaw muscles can be possibly examined by exerting a few seconds of a sustained downward pressure at the chin while the patient would attempt to keep the jaws closed.
A lot of patients suffering from Myasthenia Gravis tend to exhibit a depressed state or expression-less facial appearance. Certain actions may also be impaired, including whistling, inflating balloons, and using straws. A condition known as myasthenic snarl may also be observed whenever the patient would attempt to smile. The snarl is then followed by a contraction of the upper lip’s middle portion while the upper mouth corners will fail to contract.
During the examination, some patients tend to exhibit a weak and forced eye closure that can be possibly overcome. Bell’s phenomenon, along with upward and lateral eye rotation in an attempted closure is going to be observed once the examiner defeats the forced eye closure of the patient. Those who have mild lower facial weakness could develop transverse pucker as they attempt to hold the air within their inflated cheeks. Due to a more overt weakness in the lower facial area, the air would be able to readily escape through the lips once the cheeks of the patient are squeezed. For severe weakness of the lower facial area, the lips can’t be opposed voluntarily.
Long-Term Outlook
Long-term outlook of the Myasthenia Gravis will mainly depend on certain factors. Some people may only suffer from mild symptoms while others could eventually be confined in a wheelchair. Discuss with your doctor about the things you can do to lessen the severity of your condition. Early diagnosis and proper treatment can help to minimize the progression of the condition in most people.
