How is Myasthenia Gravis diagnosed? 5 Methods You Should Know
Experiencing symptoms of myasthenia gravis for the first time can be frightening. Muscle weakness and fatigue characterise other neuromuscular disorders as well and not knowing which one you’re dealing with can make you feel even more powerless and lost.
It doesn’t help that many people go undiagnosed for years precisely because the early symptoms of MG can be misleading. Muscle weakness is in many cases too inconsistent to constitute an immediate diagnosis and atypical signs are not uncommon. What happens, however, if you are experiencing symptoms consistent with MG, how is the autoimmune disease diagnosed? And even if you’re not, what kinds of tests need to be done so you can receive a diagnosis and begin your treatment?
These are the questions that we were asked under one of our Facebook posts. We take your health concerns and inquiries very seriously, so today on the FindMeCure blog we’re going to answer these questions and give you some tips and recommendations along the way.
Blood test
The most common way to diagnose MG is to test for antibodies the immune system produces to disrupt the signals between the nerves and the muscles. This is good news because it means that in some cases the disease can be quickly detected and treatment can start as soon as possible and you already know – the sooner, the better. A blood test is one of the less invasive diagnostic methods, however, if the antibodies are at low-level but symptoms persist additional tests will be needed. Sometimes, a low level of antibodies simply means that you have a case of ocular myasthenia, so you’re not out of the woods yet.
Ice pack test
If your doctor has suspicions about ocular myasthenia – especially if symptoms point that way and the blood test results show a low level of antibodies – an ice pack test can give some answers.
An ice pack is placed on the eye affected by ptosis (drooping eyelid) to see if the symptom will improve. It’s hypothesised that the cold can improve neuromuscular transmission, so an improvement of 2 mm or more means that the test is positive. Keep in mind that some medical professionals question this assertion and state instead that rest, not the cold, improve ptosis.
Edrophonium test
Another way to diagnose MG is by injecting edrophonium chloride – a chemical that blocks an enzyme stopping acetylcholine from transmitting signals. By blocking this enzyme edrophonium chloride allows the nerves to properly ‘communicate’ with the muscles but only if you do have myasthenia gravis – improvement is sudden and only lasts a few minutes and is a sign that the cause of fatigue is indeed MG. No improvement, on the other hand, means it’s time to look for the cause of symptoms elsewhere.
This test, however, is rarely administered and only if other methods don’t come up with conclusive results but symptoms of MG persist, especially if other possible causes are ruled out. Edrophonium chloride can have serious side effects such as slow heartbeat and difficulty breathing, so it should be only done as a last resort and in a hospital environment where the side effects can be dealt with right away.
Electromyography
If needles scare you single fibre electromyography is not the test you want to get done but in certain cases it can help your doctor arrive at a diagnosis or rule out other causes if symptoms are misleading or the blood test results are negative but MG is still suspected.
A more invasive method, electromyography involves inserting needle electrodes into your muscles – typically around the eyes, forehead and/or arms – to assess if the signals sent from the nerves to the muscles are disrupted.
CT or MRI scan
Your doctor might be looking for signs of thymoma (an abnormal growth of your thymus gland which can be linked to MG) if they suggest a CT scan. Some recent research shows that people who fight myasthenia gravis can actually benefit from a thymectomy even if no thymomas are found. The procedure itself is well-tolerated in adulthood because the gland is mostly needed through adolescence.
An MRI scan of the brain, on the other hand, is looking to rule out abnormal processes in the brain as a cause of the symptoms. Since MG early signs can be so misleading, don’t be frightened if your doctor suggests an MRI – they’re most likely just trying to get a better picture of what is going on, especially if other test results are inconclusive.
Ask for tests
We’re sharing this information with you, so you can know the various diagnostic methods that exist for myasthenia gravis. Having this knowledge is important – if you have noticed some of the early signs of myasthenia or other disorders have already been ruled out but muscle weakness and fatigue persist, you should be aware of MG and prepared to ask your doctor to run tests.
In some cases, if results are unsatisfactory or if you feel like your concerns are not taken seriously, you should know which additional tests and scans to request. Not only that but you can and should seek a second opinion if symptoms persist with no diagnosis in sight.
Your doctor might also need to test you for other conditions that can sometimes interfere with diagnosis or treatment. Thyroid disease, glaucoma, high blood pressure or another autoimmune disease are some potential causes for concern and you can ask your healthcare provider to be tested for each of them as they may pose their own unique set of challenges when it comes to your MG treatment.
Early diagnosis is the first right step in the treatment of any disease but that’s especially true when it comes to chronic illnesses. The University Hospital of Zurich is currently recruiting participants for a diagnostic clinical trial for ocular myasthenia – such trials are not uncommon. In fact, a great deal of clinical research aims at observation, screening, prevention or testing innovative healthcare programs and approaches (like this trial testing an educational intervention).
If you want to access treatments in development or donate your time to research so that medical professionals can gain a better understanding of myasthenia gravis, give clinical trials a chance. Search for a trial near you on FindMeCure to begin your journey.