Though myasthenia gravis (MG) and multiple sclerosis (MS) share some similarities, they have different causes, symptoms, and treatments.

MG is an autoimmune condition of the neuromuscular system that’s characterized by impaired communication between the nerves and muscles. This condition leads to weakness in the skeletal muscles.

On the other hand, MS is a chronic neurological condition characterized by progressive nerve damage. The condition leads to decreased central nervous system communication and neurological symptoms.

In this article, we take a look at the similarities and differences between MG and MS.

The following chart summarizes the main differences between MG and MS. The subsequent sections go into these differences in more detail.

Causesautoimmune condition in which the neuromuscular junction is attackedimmune-mediated condition in which the nerves within the central nervous system are attacked
Symptomsprimarily involves the skeletal musclescan involve any system within the body, including the skeletal muscles
Demographicsoften diagnosed from ages 40–60 and is equally prevalent across ethnicities and gendersprimarily diagnosed from ages 20–50 and is more prevalent in people assigned female at birth and those of white European descent
Diagnosisdiagnosed through a physical exam, electromyography (EMG), and antibody testingdiagnosed through a physical exam, lumbar puncture, visual evoked potential (VEP) test, and imaging tests
Treatmentmedication can help reduce immune response, while surgeries and procedures can help reduce chronic symptomsdisease-modifying therapies and other medications can help reduce chronic symptoms and relapses

MG causes

MG is an autoimmune disorder. This is a disorder that occurs when the immune system mistakenly attacks the body.

In people with MG, the immune system attacks the neuromuscular junction, which is responsible for sending signals from the nerves to the muscle fibers.

When this junction is damaged, it prevents the neurotransmitter acetylcholine from being able to transmit these signals, and the muscles can no longer contract properly.

MS causes

MS is an immune-mediated condition with autoimmune features that, like MG, is caused by the body attacking itself.

In people with MS, the immune system attacks the central nervous system, including the:

  • protective myelin around the nerves
  • myelin-producing cells
  • nerves

When these nerves become damaged, they’re no longer able to effectively send or receive signals from the rest of the body, resulting in a variety of neurological symptoms.

MG symptoms

MG primarily causes muscle weakness that is often made worse by periods of exertion or activity. Sometimes, these symptoms can appear without warning and may be confused with other neurological conditions.

The symptoms can vary from person to person and may include:

  • blurry or double vision
  • drooping eyelids
  • eye muscle weakness
  • facial paralysis
  • shortness of breath
  • speech impairment
  • trouble swallowing or chewing
  • weakness in the limbs or neck

In severe cases, weakness of the respiratory muscles can lead to complications such as respiratory failure.

MS symptoms

MS primarily causes neurological symptoms that can range in severity based on whether a person is in relapse or remission. Most of these differences depend on which stage of MS the person is in.

More common symptoms of MS include:

  • bladder dysfunction
  • bowel problems
  • cognitive disturbances
  • chronic pain sensations
  • depression
  • dizziness or vertigo
  • emotional disturbances
  • fatigue
  • itching
  • muscle spasticity or weakness
  • numbness or tingling
  • sexual dysfunction
  • trouble walking
  • vision disturbances

Other uncommon symptoms of MS may also include:

  • speech problems
  • loss of taste
  • swallowing problems
  • tremors
  • seizures
  • breathing problems
  • hearing loss

MG demographics

MG can affect anyone. According to data from 2021, the estimated number of individuals in the United States with MG is 37 per 100,000 people, with an incidence rate of 3.1 per 100,000 people.

The prevalence and incidence rates tend to increase with age for both males and females. However, there is a higher occurrence of MG among females under age 50 compared to males of the same age, as well as among males over 65 compared to females in the same age range.

[the terms “male” and “female”]

In this article, we use “male and female” to refer to someone’s sex as determined by their chromosomes and “men and women” when referring to their gender (unless quoting from sources using nonspecific language).

Sex is determined by chromosomes, and gender is a social construct that can vary between time periods and cultures. Both of these aspects are acknowledged to exist on a spectrum both historically and by modern scientific consensus.

Was this helpful?

MS demographics

MS also affects people of all races and ethnicities. However, it is most common in people who are white and of European descent.

Most cases are diagnosed between the ages of 20 and 50, but children, teenagers, and older adults can also be diagnosed with the condition. MS is three times as common in females as it is in males.

Diagnosing MG

MG is often misdiagnosed as a different neurological condition with similar symptoms, such as MS or Amyotrophic lateral sclerosis (ALS). With this in mind, the following tests may be used to determine if symptoms are due to MG or another condition:

  • Physical exam: A physical examination generally includes reviewing someone’s medical history and a full-body examination. A neurological exam can also be performed to look for abnormalities in muscle strength, muscle tone, and coordination.
  • Specialized tests: An edrophonium test checks temporary muscle improvements in people with MG. Generally, this test is most beneficial for ocular myasthenia. Single-fiber electromyography (EMG) is the most sensitive test for MG because it measures if there is an impairment between the nerves and muscles.
  • Blood tests: A blood test can be used to check for either acetylcholine receptor antibodies or anti-MuSK antibodies, both of which can be present in MG.
  • Imaging tests: Both computer tomography (CT) scans and magnetic resonance imaging (MRI) scans may be used to check for the presence of any tumors that can be linked to MG.

Diagnosing MS

MS is also a difficult disorder to diagnose because there’s no specific test for the condition. Instead, it is more likely to be diagnosed after other conditions have been ruled out using tests such as:

  • Specialized tests: A lumbar puncture can be used to remove cerebrospinal fluid (CFS) from the spine, which can then be tested for certain antibodies, proteins, or other immune system cells. A visual evoked potential (VEP) test can be used to measure the electrical activity along the optic nerve pathway, which is often one of the first pathways affected in people with MS.
  • Blood tests: A blood test can be used to help rule out any other conditions that may be causing the symptoms, such as human immunodeficiency virus (HIV) or AIDS, Lyme disease, or syphilis. In some cases, genetic testing can help determine if an underlying hereditary disorder is present.
  • Imaging tests: An MRI can help look for other underlying conditions or indications of MS, including demyelination of the nerves or other scarring and inflammation consistent with MS.

Treating MG

Although there’s no cure for MG, treatment can help manage the long-term symptoms. Treatment options for this condition include:

  • Medication: Certain medications, such as immunosuppressants and corticosteroids, can help suppress the immune system response that’s present in MG. Other medications, such as cholinesterase inhibitors, can help the nerves and muscles communicate better.
  • Procedures and surgeries: Plasmapheresis, or plasma exchange, can help remove autoimmune antibodies from the blood and decrease muscle weakness. Intravenous immune globulin (IVIG) can also change the levels of antibodies in the blood. In some people with MG, removing the thymus gland — which helps produce antibodies — can help improve muscle strength.

Treating MS

Like MG, there’s no current cure for MS, but certain medications and other treatment options can help improve symptoms and reduce relapses. Treatment options for this condition include:

  • Medication: Disease-modifying therapies (DMTs) are medications designed to help improve MS outcomes by reducing disease progression, relapses, and new damage. DMTs can be administered orally or via injection, including options such as interferon beta-1a (Avonex), interferon beta-1b (Betaseron), dimethyl fumarate (Tecfidera), and alemtuzumab (Lemtrada). Other medication options are aimed at improving the symptoms of the disease and can include corticosteroids, pain medications, antidepressants, and more.
  • Lifestyle changes: Lifestyle changes can also help people with MS manage or reduce the symptoms of the disease. Getting enough sleep, engaging in gentle exercise, or even undergoing physiotherapy are all examples of activities that can help improve the quality of life for people with MS.

What can mimic MG?

Other than MS, diseases that can mimic MG include:

  • Lambert-Eaton syndrome
  • cavernous sinus thrombosis
  • certain types of cancerous brain tumors
  • botulism
  • tick-borne disease
  • polymyositis and dermatomyositis
  • graves ophthalmopathy

What is the difference between MG and ALS?

MG and ALS can also share symptoms such as difficulty swallowing and muscle weakness. However, they are distinct conditions. MG disrupts the communication between neurons and muscles, while ALS attacks the nerve cells responsible for controlling muscle movement.

What is the life expectancy of someone with MG?

These days, most people living with MG live typical lifespans. In the past, the condition had a high mortality rate of 50-80%, but it has since been reduced to just 4.47%.

MG and MS are both immune-mediated conditions that can cause a wide range of neurological symptoms. While the two conditions may seem similar, there are notable differences that distinguish them from one another.

MG involves the neuromuscular junction, primarily affects the skeletal muscles, and is treated using medications and other procedures to help reduce immune system activation. MS involves the central nervous system, can affect the entire body, and is primarily treated using medications and lifestyle changes to reduce symptoms and relapses.

If you’ve been diagnosed with either of these conditions, receiving the proper diagnosis and getting the right treatment can help improve your overall quality of life.