Myasthenia gravis is a rare, long-term condition that causes muscle weakness. The name comes from Latin and Greek, meaning “grave muscular weakness.” For people living with the condition, everyday tasks such as lifting objects, chewing food, or simply keeping their eyes open can become genuinely difficult.
In this article, we explain what myasthenia gravis is, what causes it, how it is diagnosed, and what treatment options are available. We also look at how clinical trials are helping to develop new treatments for this condition.
What Is Myasthenia Gravis?
Myasthenia gravis (MG) is an autoimmune condition. This means the body’s immune system, which normally fights off infections, mistakenly attacks healthy parts of the body instead. In MG, the immune system interferes with the signals sent between the nerves and the muscles, making the muscles weaker than normal.
The muscles most commonly affected are those that control the eyes, eyelids, face, swallowing, and speech. Over time, the weakness can spread to the arms, legs, and the muscles involved in breathing.
MG can affect people of any age, but it most often appears in women under 40 and men over 60. It is estimated to affect around one in every 10,000 people in the UK. Whilst MG is not curable, it can be managed effectively with the right treatment, and most people with the condition are able to live a largely normal life.
For a detailed overview from a trusted medical source, visit the NHS page on myasthenia gravis.
What Causes Myasthenia Gravis?
In a healthy body, nerve signals travel to the muscles and tell them to move. At the point where the nerve meets the muscle (called the neuromuscular junction), chemicals called neurotransmitters carry the signal across the gap. In people with MG, antibodies produced by the immune system block or destroy the receptors that pick up these signals, so the muscles do not respond properly.
In most cases, the antibodies target a receptor called the acetylcholine receptor (AChR). In a smaller number of cases, they target a protein called MuSK (muscle-specific kinase). The exact reason why the immune system begins producing these antibodies is not fully understood.
The thymus gland, a small organ in the chest, is thought to play a role. In some people with MG, the thymus is unusually large or contains abnormal tissue. It is believed that the thymus may send incorrect signals to the immune system, triggering it to attack the neuromuscular junction.
Symptoms of Myasthenia Gravis
The most common early symptoms of MG affect the eyes and eyelids. These can include:
- Drooping of one or both eyelids (ptosis)
- Double vision
- Difficulty focusing
As the condition progresses, symptoms may spread to other parts of the body. Common symptoms include difficulty swallowing or chewing, slurred speech, weakness in the arms or legs, and shortness of breath during physical activity.
One important feature of MG is that symptoms tend to worsen when the person is tired and improve after rest. Many people find symptoms are worst towards the end of the day. This pattern of fluctuating weakness is one of the key signs that doctors look for when diagnosing the condition.
In rare but serious cases, MG can cause a myasthenic crisis, where the muscles involved in breathing become so weak that the person needs emergency medical support.
Common Symptoms at a Glance
The table below gives a quick summary of the main symptom areas and how they can affect daily life.
| Area Affected | Typical Symptoms | Impact on Daily Life |
| Eyes and eyelids | Drooping eyelids, double vision | Difficulty reading, driving, focusing |
| Face and mouth | Weak facial muscles, difficulty chewing or speaking | Trouble eating, changes in voice |
| Throat and neck | Difficulty swallowing, head drop | Risk of choking, fatigue when holding head upright |
| Arms and legs | Generalised weakness, especially after activity | Trouble climbing stairs, carrying objects |
| Breathing | Shortness of breath during exertion | Reduced physical activity, risk of myasthenic crisis |
How Is Myasthenia Gravis Diagnosed?
Because MG symptoms can look similar to those of other conditions, it can sometimes take time to reach a diagnosis. A GP who suspects MG will usually refer the person to a neurologist (a specialist in brain and nerve conditions) for further tests.
Common diagnostic tests include:
Blood tests to look for the antibodies that are associated with MG, particularly AChR and MuSK antibodies.
Electromyography (EMG) to measure the electrical activity in muscles and assess how well the nerves are communicating with them.
CT or MRI scans to check for abnormalities in the thymus gland.
Ice pack test in which a bag of ice is applied to a drooping eyelid. In people with MG, the cold temporarily improves muscle function, causing the eyelid to lift slightly.
Not everyone with MG will test positive for antibodies on the first test, so repeat testing or a combination of tests may be needed.
How Is Myasthenia Gravis Treated?
There is currently no cure for MG, but several treatments are available that help to manage symptoms and reduce the activity of the immune system.
Acetylcholinesterase inhibitors such as pyridostigmine are usually the first treatment tried. These medicines work by slowing down the breakdown of acetylcholine at the neuromuscular junction, which helps improve the signal between nerves and muscles.
Immunosuppressants such as steroids or azathioprine are used to reduce the activity of the immune system and lower the production of the harmful antibodies.
Thymectomy is surgery to remove the thymus gland. For some people, particularly those who are younger or have a thymoma (a tumour of the thymus), this can improve or even resolve MG symptoms over time, although this can take months or years.
Plasma exchange and intravenous immunoglobulin (IVIg) are short-term treatments used during flare-ups or to prepare someone for surgery. They work by removing or blocking the harmful antibodies in the blood.
For many people, finding the right combination of treatments takes time, and symptoms can still vary even when treatment is in place. This is one reason why research into new and better treatments for MG is so important.
Myasthenia Gravis and Clinical Trials
Clinical trials play a vital role in developing new treatments for rare conditions like MG. Because MG affects a relatively small number of people, clinical research is essential to understand the condition better and to find therapies that are safer, more effective, and easier to use.
Several newer treatments for MG, including FcRn inhibitors and complement inhibitors, have shown real promise in recent clinical trials. These approaches work in different ways to reduce the harmful antibodies that cause muscle weakness in MG. They represent a new generation of targeted therapies that could offer better results for people whose symptoms are not well controlled by existing medicines.
At 4MCS, we are currently running a myasthenia gravis clinical trial at our research facilities in London and Manchester. If you have been diagnosed with generalised myasthenia gravis (gMB), you may be eligible to take part.
What Does Taking Part in a Trial Involve?
Taking part in a clinical trial is always a personal choice and one that should feel right for you. At 4MCS, every participant goes through a detailed screening process before joining a study, to make sure the trial is safe and appropriate for them.
During a trial, participants attend regular visits to our facility. At each visit, the research team will carry out health checks, monitor for any changes in symptoms, and provide the study treatment. Participants are supported by a dedicated team throughout the process.
Trials at 4MCS are unpaid, but reasonable travel expenses are covered. If you have questions about what to expect, our frequently asked questions page covers many of the things people want to know before getting involved.
Could You Take Part?
If you or someone you know has been diagnosed with myasthenia gravis, taking part in a clinical trial could be a way to access new treatments and contribute to research that may help others in the future.
4MCS has over 130 years of combined experience in clinical research across Phase 1b to Phase 4 trials. Our team is MHRA-approved and operates from two research sites in Ilford (London) and Swinton (Manchester). To find out more about how to take part in clinical research in the UK, visit our information hub.
