(MENAFN- The Conversation) Former tennis star Monica Seles recently revealed she is living with the rare disease myasthenia gravis, which affects 12 in 100,000 people globally.

Seles explained her first symptoms appeared suddenly around three years ago. She began experiencing double vision and weakness in her arms and legs. This made everyday activities, such as drying her hair, a challenge.

So what is this condition?

Myasthenia gravis is a chronic autoimmune disorder, where your own immune system disrupts the communication between nerves and skeletal muscle.

In healthy people, nerve cells send a chemical messenger called acetylcholine. This tells muscles to contract by binding to its receptor.

In myasthenia gravis, antibodies block or destroy these receptors, so the signal is weakened or lost.

The result is muscle weakness that worsens with activity and improves with rest. This is called“fatigueability”.

What are the symptoms?

Muscle weakness can affect everyday functions such as walking, speaking, breathing and swallowing.

Symptoms, which can appear suddenly, may also affect the eyes, causing drooping eyelids and double vision.

In some cases, weakness of the muscles makes it difficult to breathe or can result in choking on food or water. This is called a“myasthenic crisis” and requires hospitalisation and sometimes life support.

In our research interviews, a young woman in her 30s living with myasthenia gravis described what it feels like to experience a crisis:

Another man in his 70s explained just how suddenly the disease can appear:

What causes it and who does it affect?

It's unclear what causes the disease but it's not thought to be hereditary.

There is some evidence it is more likely to occur with other autoimmune conditions such as autoimmune thyroid disease, lupus and rheumatoid arthritis but the evidence remains incomplete.

Myasthenia gravis can appear at any age. Early onset is more common in women (often before 40), while men are more likely to develop myasthenia gravis later in life.

How is it diagnosed?

Despite its serious impact, myasthenia gravis remains under-recognised and is difficult to diagnose. The diagnosis is“clinical”, which requires a doctor with experience in myasthenia gravis to make a judgement, based on the information available.

A handful of tests are available to support the diagnosis: blood tests for antibodies, nerve conduction studies and needle electromyography, which record the electrical activity of nerves and muscles. But these are far from perfect in establishing the diagnosis.

How is it treated?

There is currently no cure for myasthenia gravis, but a range of treatments can help manage symptoms. These include:

• oral medicines called anticholinesterase inhibitors, which temporarily improve communication between nerves and muscles

• immunosuppressant medications, which are generally taken by mouth. These dampen the immune system and reduce its attack

• plasma exchange and intravenous immunoglobulin (IVIg), which is a blood product. These are resource-intensive therapies that remove or block the harmful antibodies. These treatments require hospital admission for at least half a day to administer via an intravenous drip

• in some patients, surgery is performed to remove the thymus gland, which is located in the chest between the lungs. This plays a key role in the abnormal immune response in people with myasthenia gravis.

While most treatments are subsidised through the health system, access remains a challenge for some people. Plasma exchange and IVIg are not available in all hospitals, for example, meaning patients in regional areas may face long travel distances or delays in receiving urgent care.

What is the long-term outlook?

While myasthenic crises are life-threatening, the evidence so far suggests the disease won't have a significant impact on life expectancy for most people. Treatments aim to reduce disease activity rather than offering a complete cure.

People with myasthenia gravis can have very different journeys with their disease. Some may need frequent hospital admissions, and around 10% have a form of disease which is difficult to treat.

Others may experience minimal symptoms requiring little to no treatment.

Many find their symptoms are unpredictable. As a woman in her 60s, who has had myasthenia gravis for ten years, told us:

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