Myasthenia Gravis

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This leaflet is intended to answer some of the questions of patients or carers of patients diagnosed with Myasthenia Gravis under the care of University Hospitals Sussex NHS Foundation Trust.

What is myasthenia gravis (MG)?

MG is a neuromuscular disorder causing weakness of the muscles which control some movements.

It is often affected by fatigue (tiredness) and can cause problems with speech, swallowing, facial expression and eye movements as well as muscles which move the arms and legs.

MG is an autoimmune disorder where the immune system mistakenly attacks healthy tissue. The body produces antibodies which block the messages that pass from the nerve endings to the muscles, meaning that your muscles do not contract well and become weak.

How common is it?

Myasthenia gravis affects about one person in every 10,000 in the UK. It can develop at any age, but is more common in women under the age of 40 and men over the age of 60. However, in recent years, increasing numbers of patients over the age of 60 are developing the condition.

What causes MG?

The exact cause of MG is unknown but sometimes it can be associated with tumours in the thymus gland. MG can affect the whole body or just affect the eyes (Ocular MG). There is no cure but long term remission is possible.

What are the symptoms of MG?

MG is characterised by weakness of the voluntary muscles i.e. those that we would move voluntarily. The weakness gets worse the more the muscle is used. Some general symptoms show as difficulty in:

Breathing.
Swallowing or chewing.
Walking.
Keeping head upright.
Talking.

Eye symptoms include:

Double vision.
Drooping eyelids (ptosis).

How is it diagnosed?

If you present to the orthoptist with double vision or droopy eyelids caused by muscle weakness which gets worse with fatigue or is very variable then MG may be suspected. The ophthalmologist will arrange for you to have blood tests which can determine if MG is the cause.

What is the treatment for MG?

The treatment usually involves taking drugs called Acetylcholinesterase Inhibitors. These work to improve the connections between the nerve endings and the muscles. The doctor who prescribes them can tell you more about how they work.

If there is a tumour of the thymus gland, it is removed and then medical treatment may be required afterwards.

In order to receive these treatments you will need to be referred to a neurologist or endocrinologist.

How are the eye symptoms treated?

Eye symptoms in MG are often very variable. This makes relief challenging. There are several ways to relieve double vision:

If the eyelids are drooping they may cover the eye meaning double vision is not noticed.
It may be possible to use a prism to join up the double vision but it may not be very satisfactory due to the variable nature of MG.
In some cases it may be better to patch one eye for a more constant relief.

If patients are unable to open the eye(s) at all it may be necessary to tape either eyelid open temporarily so that they can see.

When the lids are taped you may need to use a lubricant gel or drops to protect the front surface of the eye.