Myasthenia gravis (MG) is an autoimmune neuromuscular condition, characterised by weakness and fatiguability of the skeletal muscles. Skeletal muscles are muscles that allow voluntary movement, such as muscles controlling the eye and eyelid, facial expressions, talking, chewing, swallowing and the arms and legs.¹ MG is caused by disruption in the transmission of signals from nerve cells (neurons) to those muscles at the neuromuscular junction (NMJ). Weakness tends to increase during periods of activity and improve temporarily after rest.^1,2 It may also be exacerbated by heat and stress.² MG can be life-threatening in instances where respiratory muscles are affected and result in difficulty in breathing (myasthenia crisis).^2,4

MG can occur at any age, with the adult onset (ORPHA:391490 Adult-onset myasthenia gravis) most common in females before age of 40 years and males after 50 years, whilst juvenile myasthenia gravis (ORPHA:391497 Juvenile myasthenia gravis) refers to onset before 18 years of age.³ There is also a transient neonatal form of MG (ORPHA:391504 Transient neonatal myasthenia gravis) that can occur in some (but not all) newborns born to mothers with MG – this is due to transfer of maternal autoantibodies through the placenta during pregnancy, resulting in poor muscle strength (hypotonia) and feeding difficulties in some newborns, but symptoms are not permanent.^2,3

There are other myasthenic (muscular weakness) disorders, such as congenital myasthenic syndrome (CMS) which is a genetic condition; and Lambert-Eaton myasthenic syndrome (LEMS) which is an autoimmune disorder that affects skeletal muscles and the autonomic nervous system.

Synonyms: acquired myasthenia; autoimmune myasthenia gravis.¹

Universal rare disease classifications provide a common language for recording, reporting and monitoring diseases. Please visit the Rare Disease Classifications page for more information about these internationally recognised classifications.

ORPHA:589 Myasthenia Gravis

ICD-11: 8C60 Myasthenia gravis

MG is characterised by fatiguable weakness (weakness that worsens with physical activity and may improve temporarily with rest).^1,2 MG can be restricted to the muscles of the eyes (ocular MG) or affect multiple skeletal muscle groups (generalised MG), such as muscles of the face, neck, throat, eyes and limbs. Symptoms may include drooping eyelid (ptosis), blurred or double vision, slurred speech, difficulties in chewing and swallowing, weakness in arms and legs and in lifting head, and difficulties in breathing.^1-5 These symptoms can be highly variable between individuals as well as across an individual’s lifetime.

Some individuals with MG may have a tumour in their thymus (thymoma).^1,2,6 An increased likelihood of developing other autoimmune diseases, particularly thyroid-related autoimmune conditions, has also been observed in people living with MG.^2,6

Please speak to your medical team to learn more about the symptoms and complications of MG.

Rare diseases are often serious and progressive, exhibiting a high degree of symptom complexity, leading to significant disability. Majority of the estimated two million Australians living with a rare disease meet the Australian Government’s definition for disability (in accordance to the Australian Public Service Commission and Australian Bureau of Statistics), and many experience severe and permanent disability impacts. If you or someone you care for is experiencing disability-related impacts from a rare condition, please speak with a health or disability professional for advice. Information about relevant disability support can be found at the RARE Portal’s Disability Support Information page.

MG is an autoimmune condition. In MG, there is a defect in the post-synaptic neuromuscular junction, which affects the transmission of signals from neurons (nerve cells) to muscles.^2,3 This defect is usually caused by one’s own body producing auto-antibodies that attack components of the neuromuscular junction, such as anti-AChr antibodies targeting the acetylcholine receptors on muscle cells and anti-MuSK antibodies targeting muscle-specific receptor tyrosine kinase.^1,3,6

Anti-LRP4 (low density lipoprotein receptor-related protein 4) antibodies have also been associated with MG.⁶ There are also individuals who are seronegative, in that they have been diagnosed with MG due to clinical symptoms, but auto-antibodies have not been detected. In addition, some cases of MG have also been linked to tumours in the thymus gland.¹

MG is not a genetic condition, but a predisposition to developing autoimmune conditions may sometimes be present in families.^2,6

MG may be diagnosed using a blood test to detect for the presence of auto-antibodies that have been associated with MG.^2,4,6 Not all individuals with MG may have these auto-antibodies.^1,2

Other diagnostic methods for MG may include:²

• electromyography (EMG) or single fibre electromyography (SFEMG) to assess nerve-to-muscle signal transmission
• a chest computed tomography (CT) scan to detect for a tumour in the thymus (thymoma) or an enlarged thymus gland

A differential diagnosis can rule out other conditions that have similar symptoms, such as Lambert-Eaton myasthenic syndrome (LEMS), cavernous sinus thrombosis, brainstem gliomas, multiple sclerosis, botulism, tick-borne disease, polymyositis, dermatomyositis, and graves ophthalmopathy.⁷

Please speak to your medical team to learn more about the available diagnostic pathways for MG.

There is currently no curative treatment for MG. MG is generally a long-term condition that requires continual treatment; however, some individuals may achieve remission where they do not experience any symptoms.²

Treatment of MG is targeted at controlling the condition and managing symptoms. Treatment involves a multidisciplinary care team and may include:^2,4,6

• medication containing anti-acetylcholinesterase agents; this treatment is fast-acting, but short-lived (works quickly but effects do not last long)
• medication that suppresses the immune system, such as corticosteroids and steroid-sparing agents
• plasmapheresis – where the liquid portion of blood that contains the auto-antibodies (plasma) are removed and replaced with treated or new plasma
• intravenous immunoglobulin (IVIg) – infusion of plasma solution from healthy donors

A thymectomy (removal of the thymus gland) may also be recommended for some individuals living with MG.^4,5

Please speak to your medical team to learn more about the possible treatment or management options for your condition. Treatment will depend on an individual’s specific condition and symptoms. It is also important to stay connected to your medical team so that you can be made aware of any upcoming clinical trial opportunities.

Clinical care for rare diseases often involves a multidisciplinary team of medical, care and support professionals. Please note that the information provided here is as a guide and that RVA does not necessarily monitor or endorse specific clinics or health experts.

Healthcare professionals involved in the treatment of MG may include general practitioners (GP), neurologists, ophthalmologists, occupational therapists, speech pathologists, physiotherapists, and exercise physiologists. The need for different healthcare professionals may change over a person’s lifetime and extend beyond those listed here.

Clinics:

Neurosciences Department, Concord Repatriation General Hospital (NSW)
Website: https://www.slhd.nsw.gov.au/concord/department-neurosciences-services.html

The neuroimmunology clinic at Concord Hospital provides services for patients with neurological disorders with an immunologic basis including myasthenia gravis and multiple sclerosis and includes clinical research and access to clinical trials.

Neurology Clinic, Princess Alexandra Hospital (QLD)
Website: https://www.metrosouth.health.qld.gov.au/services/neurology/neurology-princess-alexandra-hospital

Myasthenia gravis is one of the conditions treated at the Princess Alexandra Hospital neurology clinics. The neurology team includes doctors, nurses, occupational therapists, physiotherapists and speech pathologists.

The Neuroimmunology Centre, Royal Melbourne Hospital (VIC)
Website:https://www.thermh.org.au/services/neurology-stroke/neurology-stroke-services/multiple-sclerosis-neuroimmunology

The Neuroimmunology clinics at Royal Melbourne Hospital are dedicated to the assessment and long-term management of people with a possible or definite diagnosis of MS and other neuroimmunological conditions, including neuromyelitis optica, neurosarcoidosis, autoimmune encephalitis, cerebral vasculitis and myasthenia gravis.

We are not aware of any current clinical care guidelines for MG in Australia. If you know of any relevant care guidelines, please let us know via the Contribute page.

The following guidance is available from international experts outside Australia; however, there may be information that is not relevant or applicable to the Australian context, and may not be up to date:

• International Consensus Guidance for Management of Myasthenia Gravis – developed by a panel of 15 international experts from 10 different countries; please note this was last updated in 2020.
• Guidance for the management of myasthenia gravis (MG) and Lambert-Eaton myasthenic syndrome (LEMS) during the COVID-19 pandemic prepared by an international working group of MG experts and endorsed by American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM); please note that this was prepared in 2020.

Individuals living with rare diseases may have complex medical issues and disabilities, which are not always visible. It is often useful to refer to their medical history as well as personal information such as a medical card, doctor’s letter, or if available, a rare disease passport, for relevant information.

It may be important to consider the following when managing individuals living with RD at emergency departments/services:

• MG can affect respiratory muscles and result in breathing difficulties (myasthenia crisis), which can be life threatening and is a medical emergency.^2,4

International Consensus Guidance for Management of Myasthenia Gravis: 2020 Update (Table 1) lists drugs to avoid or use with caution when treating individuals with MG.⁵

OrphanAnesthesia has Anaesthesia recommendations for Myasthenia Gravis; please note this was last updated in 2019.

Information about myasthenia research in Australia can be found at:

• Myasthenia Alliance Australia: Research updates
• Myasthenia Alliance Australia: Latest research

There are specific considerations around participating in rare disease research, including clinical trials. It is important to be mindful of issues such as data privacy, research ethics, consent and differences in research regulations between Australia and other countries.

If you are interested in finding clinical trials for your condition, please visit the following websites; however, there may not be any clinical trials available:

• Australian Clinical Trials
• ClinicalTrials.gov

It is best to discuss your interest in any clinical trials with your medical team to determine suitability and eligibility.

Please note that RVA does not necessarily monitor or endorse each group/organisation’s operational governance and activities.

Australian Organisations:

Myasthenia Alliance Australia (MAA)
Website: https://myastheniaalliance.org.au/

Below are the organisations that make up MAA; both organisations provide support for all Australians living with myasthenia, including their families and carers, regardless of location:

Myasthenia Gravis Association of Queensland Inc.
Website: https://www.mgaq.org.au/

The Australian Myasthenic Association in NSW Inc.
Website: https://www.myasthenia.au/

Please note that RVA does not monitor or endorse each group/organisation’s operational governance and activities. When engaging with a group, please consider the information on the RARE Portal’s Finding Helpful Peer and Community Supports page.

MG varies between individuals, and each person’s experience is unique.

Personal story shared with RVA: Sophie’s Story

If you would like to share your personal story with RVA, please visit the Rare Voices Australia: Share Your Story page. RVA will consider your story for publishing on our website and inclusion on the RARE Portal.

Myasthenia Alliance Australia and its state organisations provide support resources relevant for individuals living with MG:

• Myasthenia Alliance Australia: Peer Support
• Myasthenia Gravis Association of Queensland Inc.: Resources
• Australian Myasthenic Association in NSW: Patient Support

The Loop – Your Neuromuscular Resource Hub: Funding provides information on available social services that are relevant to the neuromuscular community.

For information on available government and social services that provide support for individuals with a rare disease, please visit the National and State Services pages.

People living with a rare disease, including families and carers, often face unique challenges such as diagnostic delays, misdiagnoses, limited treatment options, and limited access to rare disease specialists and support. These challenges may impact people’s emotional wellbeing and quality of life. Many people find it helpful to seek mental health and wellbeing support to cope with ongoing stress and uncertainty. Connecting with people who have shared experiences through a support group may also be helpful. Information about relevant mental health and wellbeing support can be found at:

• Mental Health and Wellbeing Support for Australians Living with a Rare Disease
• The National and State Services pages underneath the ‘Mental Health’ sections listed

Further information on MG or neuromuscular conditions in general, can be found at:

• healthdirect: Myasthenia gravis
• Better Health Channel: Myasthenia gravis
• Genetic and Rare Diseases (GARD) Information Center: Myasthenia Gravis
• National Organization for Rare Diseases (NORD): Myasthenia Gravis
• RARE Portal: Neuromuscular Conditions
• The Loop – Your Neuromuscular Resource Hub

• Myasthenia Alliance Australia: Health Professionals
• Healthed: Myasthenia gravis is on the rise (podcast)
• Clinical features, treatments, their impact, and quality of life for Myasthenia Gravis patients in Australia
• Royal College of Pathologists of Australasia (RCPA): Acetylcholine receptor Ab
• Online Mendelian Inheritance in Man, OMIM^®: #254200 Myasthenia Gravis; MG
• Orphanet: Myasthenia Gravis
• Human Phenotype Ontology (HPO): Myasthenia Gravis

This page has been co-developed by Rare Voices Australia (RVA)’s RARE Portal team in consultation with Myasthenia Alliance Australia, which represents Myasthenia Gravis Association of Queensland and Australian Myasthenia Association of New South Wales.

If you are aware of any additional information that may benefit stakeholders with an interest in this page, or if you notice any broken links or inaccurate information, please let us know via the Contribute page.