Introduction to Myasthenia Gravis
Myasthenia graves is an autoimmune disease which causes certain muscles to become weak.
What is Myasthenia Gravis?
Myasthenia graves is an autoimmune disease which causes certain muscles to become weak. Muscles involved in voluntary movement are usually affected, especially those controlling eye and eyelid movement, chewing, fascial expression, speaking and swallowing. 1 in 10, 000 people are affected but most commonly women under 40 are be affected. The disease can also temporarily be passed to babies of affected mothers but this clears after a few months so is not something to be too worried about.
What are the causes for Myasthenia Gravis?
The body’s own immune system produces antibodies which block receptors in the muscle. The body sends nerve signals to muscles to initiate activity. The blocking of these receptors prevents this neural transmission to the muscle and so the muscle does not work.
What are the symptoms of Myasthenia Gravis?
The main symptom is muscle weakness. Symptoms can come on quite suddenly but sometimes takes time to be diagnosed as muscle weakness is a symptom of many diseases. The severity of muscle weakness differs between people. The eye muscles are often the first to be affected. People can experience drooping eyelids or double vision and usually at the end of the day the muscles are more tired. The condition isn’t painful but following exertion, muscles can feel achey, particularly after periods of physical activity. If muscles of swallowing or muscles around the mouth or tongue are affected, it might be difficult swallowing and breathing. These problems may require urgent admission to A&E. If muscles in the arms and legs are affected, there may be problems with walking and performing physical tasks such as lifting.
How is Myasthenia Gravis treated?
If symptoms are mild, people find that getting plenty of rest is sufficient to improve symptoms without the need for medication. Severe symptoms can be treated with medication. Pyridostigmine is an inhibitor of an enzyme which breaks down the chemical transmitter used in neural transmission. This increases the level of transmitter so muscle contraction is improved. This is effective treatment but in most people is not suitable in the long-term. Steroid tablets such as prednisolone are then used at a low dose. In cases when steroid tablets aren’t sufficient, immunosuppressant medication may be prescribed, either azathioprine, mycophenola or methotrexate.
In some cases, a gland called the thymus is removed to improve symptoms and is recommended for people under 45 years in certain situations.
In severe cases, plasmapheresis and immunoglobulin therapy may be needed, especially when a person’s muscle weakness is affecting their swallowing or breathing. Plasmapheresis is when blood is filtered through a machine to remove the antibodies causing you harm. Immunoglobulin therapy is injection of immunolgoblulin from a healthy person which changes the way your immune system works. The benefits of these treatments only last a few weeks and aren’t suitable in the long term, only for people who are seriously ill.