The Main Causes of Myasthenia Gravis You Should Be Aware Of

Thymus Gland

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  • Myasthenia gravis is a neuromuscular autoimmune condition that attacks the nerve-muscular junctions of your voluntary muscles, causing muscle weakness in the affected area
  • It’s estimated that 15 percent of people diagnosed with myasthenia gravis develop thymoma, or a tumor in the thymus gland

Myasthenia gravis is a neuromuscular autoimmune condition that attacks the nerve-muscular junctions of your voluntary muscles, causing muscle weakness in the affected area. Voluntary muscles are those that you can freely control, such as your arms, legs and eyelids.1

For your muscles to move, they need neurotransmitters to receive instructions. In this case, voluntary muscles use acetylcholine, which travels through your nerves and arrives at the receptor sites of the muscles.

When your immune system produces antibodies that target these sites and neurotransmitters, less information is sent, leading to muscle weakness.2

Aside from blocking acetylcholine, myasthenia gravis can be caused by blocking a specific protein called tyrosine kinase. This protein helps form the nerve-muscular junctions, and when your immune system blocks its growth, myasthenia gravis can develop.3

The Role of the Thymus Gland in Myasthenia Gravis

The thymus gland is found in your chest area, underneath the breastbone. It forms before birth and continues to function until you reach puberty, helping build your immune system by producing the necessary antibodies to protect yourself from diseases.

Once it stops functioning, it gets smaller and is slowly replaced by fat. By the time you’re 75 years old, the gland will be nothing more than just a small, fatty tissue.4

In people with myasthenia gravis, the thymus gland continues to remain large. This condition is called thymic hyperplasia, and it’s estimated that 65 percent of myasthenia gravis patients develop it.

In thymic hyperplasia, the immune system has trouble distinguishing disease-causing cells from your normal cells, leading to instances where your own body is attacked.5 Note that thymic hyperplasia is not only caused by myasthenia gravis. It may arise because of other conditions, such as cancer or using steroidal medications.6

On the other hand, it’s estimated that 15 percent of people diagnosed with myasthenia gravis develop thymoma, or a tumor in the thymus gland.7 Most thymomas are benign, but some can become malignant, and therefore will need treatment.8

Risk Factors of Myasthenia Gravis

There are several risk factors involved in myasthenia gravis, such as:9

Age: The disease can appear in all ethnic groups, genders and age groups, but women under the age of 40 and men over the age of 60 are more susceptible to it.

Childbirth: There’s a chance that a mother can pass on a temporary form of myasthenia gravis to her newborn child, if she has the condition during childbirth. This condition is known as neonatal myasthenia gravis.

Family: Myasthenia gravis has a hereditary component, but doctors are not sure how it is passed on. If you have a family history of this condition, this type is known as myasthenic syndrome.10

Lifestyle: If you regularly experience stress, illness and fatigue, your risk of developing myasthenia gravis increases.11

Medication: Taking medications such as beta blockers, certain antibiotics, phenytoin and quinine can increase your risk of developing myasthenia gravis. If you’re taking any of the mentioned medicines for a current health condition, consult with your doctor to find safer alternatives.12

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