Myasthenia Gravis: Symptoms & Treatment

Myasthenia gravis is a chronic autoimmune neuromuscular illness that produces weakening in the skeletal muscles, which worsens during periods of activity and improves when in rest. 

• These muscles are responsible for the functions of breathing and moving bodily parts, including the arms and legs.
• Myasthenia gravis is of Latin and Greek origin, and its term means "grave or severe muscle weakness." 
• The majority of cases of myasthenia gravis are not as extremely critical, despite the fact that there is no known cure. 
• Symptoms can typically be managed with the help of available medicines, allowing patients to enjoy a high quality of life. 
• The life expectancy of the majority of affected persons is average.

Read More: Tumor

Key terms: Autoimmune Diseases, Nicotinic Acetylcholine Receptors, Myasthenia gravis, Muscles, Neuromuscular, Thymus

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Myasthenia Gravis Definition

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Myasthenia Gravis can be defined:

• It is a rare chronic autoimmune disease marked by muscular weakness.
• It includes the circulation of antibodies which causes nicotinic acetylcholine receptors to be blocked at the postsynaptic neuromuscular joint.

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Types of Myasthenia Gravis

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There are basically several types of Myasthenia Gravis and few of them are as given below:

Congenital Myasthenia Gravis

Congenital Myasthenia Gravis can be stated as a condition in which muscle weakness gets worsened with physical exertion.

• It is basically inherited. It can be inherited from both the parents that are involved in nerve- muscle communication.
•  It is estimated to occur in 2-12 people per million.

Ocular Myasthenia Gravis

Ocular Myasthenia Gravis is explained as a condition in which the muscles that move eyes and eyelids get affected. It is estimated to occur in 1/5000.

Generalized Myasthenia Gravis

Generalized Myasthenia Gravis is defined as a condition in which multiple muscle groups are affected throughout the body

• It is also called Generalized Myasthenia Gravis.
• It is estimated to occur in 14-40 per million.

Transient Neonatal Myasthenia Gravis

Transient Neonatal Myasthenia Gravis can be defined as a postsynaptic neuromuscular transmission defect. It is found in study that 21% of the infants born are acquired with Transient Neonatal Myasthenia Gravis.

Juvenile Myasthenia Gravis

Juvenile Myasthenia Gravis is stated as a situation in which an autoimmune disorder of the neuromuscular junction results in ocular manifestations or generalized weakness, with onset before 18 years of age. It is estimated to occur in 1 per million or 2 per million.

Read Also: Genetic Disorders

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Symptoms of Myasthenia Gravis

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Muscle weakness caused by Myasthenia Gravis worsens as the affected muscle is used. The symptoms of this condition also improve with rest. Moreover, the symptoms progresses with respect to time since the onset of the disease.

• The primary symptom of Myasthenia Gravis is the weakening of voluntary skeletal muscles which control muscles in specific areas.
• The muscles so weakened fail to contract as they become unresponsive to impulse.

The most common myasthenia gravis signs and symptoms that can be seen are:

Eye muscles

More than 50% of the people who suffer from Myasthenia Gravis first see the eye muscle symptom.

• In this one or both the eyelids droop. This is called Ptosis.
• The person faces double vision or diplopia and this can be horizontal or vertical.
• Diplopia can be improved or resolved by closing one eye.

  Drooping of eyelids due to Myasthenia Gravis

Read Also: Saliva: Roles, Importance & Digestion of Food 

Face and Throat Muscles

The face and throat muscle symptom is faced by almost 15% of the people suffering from Myasthenia Gravis.

• In this the speaking is impaired. Your speech may sound nasal.
• One can face difficulty in swallowing. You might get choked and cannot drink properly.
• Trouble during chewing. The muscle used for chewing gets tired half a way.
• Change in facial expression. This condition also affects simple facial movements such as, smiling.

  Facial expression due to Myasthenia Gravis

Neck and Limb muscles

Myasthenia Gravis causes weakness in the neck, arms, and legs.

• Weakening in leg muscles impairs walking.
• Weak neck muscles make it hard to hold the head in proper position.

  Weak neck muscle due to Myasthenia Gravis

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Causes of Myasthenia Gravis

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The primary cause for Myasthenia Gravis is when there is improper communication between nerves and a muscle which is interrupted by a neuromuscular joint.

• The other leading myasthenia gravis cause is that the neuromuscular joint is affected with acetylcholine which causes muscle contraction that no longer produces contractions required in muscle movement.
• Antibodies too can block the function of a protein called muscle-specific receptor tyrosine kinase, sometimes referred to as Musk.
• The thymus gland which is situated in the upper chest and beneath the breastbone triggers or maintains the production of the antibodies that block acetylcholine.

Myasthenia Gravis Complications

Some of the Complications of Myasthenia Gravis include:

1. a) Myasthenic crisis:

• Myasthenic crisis is a life threatening condition in which the muscles controlling respiration become too weak to work.
• In such cases emergency breathing treatment is assisted to the patient.

1. b) Thymus gland tumors:

• Some people get tumors in the thymus gland, a gland which is involved in a healthy immune system.
• Most of the tumors called thymomas are not cancerous but can lead to low immune system.

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Myasthenia Gravis Diagnosis

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As we have understood the myasthenia gravis meaning, we should understand how such a condition can be diagnosed.

• This is a long term auto immune condition which results in muscular weakness. And may get worse on improper treatment.
• The first test for diagnosis is a blood test which tests for antibodies, which acts as a barrier for communication between muscles and nerve cells. High antibodies indicate the condition is present.
• The second test is a nerve test and done after a blood test is found negative. The test consists of needles inserted in the eyes or forehead and the test is known as electromyography. The electrical recordings indicate whether the condition is present or not.
• A CT scan or MRI scan of the chest helps to assess the size of the thymus. An edrophonium test may also be done.

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Treatment Of Myasthenia Gravis

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There is no particular cure for Myasthenia Gravis, but treatment can help relieve signs and symptoms. Though this disease can affect people of any age, it's more common in women younger than 40 and in men older than 60. But it does have treatments like medication and therapy.

• As it is caused by the malfunction of the immune system and attacks body tissues and hence is a non-curable disease.
• The treatment is to deal with symptoms and control activity of the immune system.
• Medications include cholinesterase inhibitors, corticosteroids and immunosuppression that help to control the symptoms of the condition and bring them into manageable proportions.
• Intravenous therapy helps in treating the condition in the short term or before conducting surgery or any therapy.
• Another treatment is surgery of a tumor in the thymus gland. A thymectomy is done through open surgery and minimally invasive therapy.

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Things to Remember

• Myasthenia gravis was first recognized by Thomas Willis, a 17th century Oxford physician.
• Myasthenia Gravis is a form of autoimmune disease.
• In Myasthenia Gravis, there is low activity or even over activity of the immune system which leads the body to attack and damage its tissues.
• Myasthenia Gravis occurs at any age but can be seen often at the age of 20-40 in women and 50-80 in men.
• The Myasthenia Gravis symptoms include drooping of eyelids, neck is not held in position due to weak neck muscles, and impaired walking etc.
• In myasthenia gravis, your immune system attacks a receptor in your muscles and the signals to move the muscle can’t get through.

Read More: Immunity

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Previous Year Questions

1. Stimulation of a muscle fiber by a motor neuron occurs at….[NEET 2014]
2. In human body which one of the following is an atomically correct ?...[NEET 2007]
3. A deltoid ridge occurs in...[NEET 1990]
4. Number of cervical vertebrae in camel is...[NEET 1990]
5. Calcium is important in skeletal muscle contraction because it...[NEET 2018]
6. Colle's fracture is associated with...[BHU UET 2009]
7. Which one of the following items gives its correct total number?...[NEET 2008]
8. ATPase enzyme needed for muscle contraction is located in -[NEET 2004]
9. Inter-articulated disc is found in...[BHU UET 2005]