Myasthenia gravis (MG) and multiple sclerosis (MS) are both chronic conditions with quite a bit in common. However, there are some key differences that set them apart. Although it’s very rare, some people do end up with both conditions at the same time. This may not be random — some researchers believe MG and MS likely share certain risk factors.

Here are some of the similarities and differences between these two neurological disorders.

Similarities Between Multiple Sclerosis and Myasthenia Gravis

Myasthenia gravis and multiple sclerosis share several similarities, including some common causes and symptoms, and they may be treated by the same doctors.

1. They’re Both Autoimmune Conditions

The term “autoimmune” means that the immune system mistakenly attacks healthy tissues. Different autoimmune disorders involve different body systems. In both myasthenia gravis and MS, a person’s immune system mistakenly attacks parts of their body.

In myasthenia gravis, the immune response is against neurotransmitter receptors on the surface of muscles. This impairs the communication between nerves and muscles, leading to muscle weakness.

In MS, the immune response is against the myelin sheath (fatty protective lining) of neurons in the central nervous system, which comprises the brain and spinal cord. The myelin sheath is essential for the proper transmission of nerve impulses, and its damage leads to a variety of neurological symptoms.

Health experts are still learning exactly why certain people are more likely to develop autoimmunity. While they haven’t figured it out completely, there are some possible genetic links. If your close relatives have an autoimmune disease, you’re more likely to get one as well.

In addition, autoimmune diseases are triggered by inflammation. High anxiety levels, poor sleep, and other stressors can make the symptoms worse. There’s some evidence that heat is a more common trigger for MS flare-ups, and surgery tends to trigger myasthenia gravis.

2. Younger Women Are More Likely To Develop Both

More women than men develop autoimmune conditions — especially women who haven’t reached menopause. Twice as many females are diagnosed with MS than males, according to NORD, most commonly between the ages of 20 and 50 years old. More women than men are diagnosed with myasthenia gravis, especially in their 20s and 30s, per NORD.

However, it’s possible to get either condition later in life, and men can certainly develop either condition. For men, the symptoms of myasthenia gravis tend to show up around age 50 or 60 versus ages 20 or 30 for women, according to NORD.

3. Impaired Movement and Muscle Dysfunction Are Shared Symptoms

Both MG and MS cause impaired movement and muscle dysfunction. MS can lead to difficulty walking or moving arms, while MG primarily causes muscle weakness affecting walking, lifting, talking, chewing, swallowing, and breathing​​​​.

4. Both Conditions Often Affect Eyes and Vision

Myasthenia gravis and multiple sclerosis affect the muscles, including the ocular muscles that control the eyes. Sometimes, vision problems are one of the first symptoms when developing one of these conditions. Among vision problems associated with myasthenia gravis are ptosis (drooping eyelids) and double vision.

Double vision is also one of the symptoms of MS. In addition, nystagmus (involuntary eye movements) may affect people with MS. Optic neuritis (inflammation of the optic nerve) is another MS-related eye problem that can cause pain and temporary vision loss.

5. Neurologists May Treat Both Conditions With Immunosuppressants

Whether you have myasthenia gravis, multiple sclerosis, or both, you’ll need to see a neurologist for treatment. Neurologists are medical doctors who specialize in treating diseases of the nervous system. Some neurologists have additional training in neuromuscular disorders such as myasthenia gravis. Additional specialists may also be involved in your care, such as an eye doctor (ophthalmologist) if you have eye symptoms and a rheumatologist to help address the autoimmune aspects of the disease.

Since the underlying problem in myasthenia gravis and multiple sclerosis involves problems with the immune system, some treatment options may overlap. Medications that suppress the immune response help tamp down an overactive immune system responsible for nerve damage. While these immunosuppressants can be very effective in slowing down both MS and MG disease progression, one of their main side effects is a greater vulnerability to getting sick. People taking immunosuppressants will need to be vigilant about washing their hands, getting their recommended vaccines, and treating infections right away.

Differences Between Multiple Sclerosis and Myasthenia Gravis

Myasthenia gravis and multiple sclerosis may seem very similar, but they’re distinct conditions with a few key differences.

1. They Affect Different Parts of the Body

In myasthenia gravis, the immune system attacks the neuromuscular junction, which is the connection between the nerves and the muscles. However, in MS, the myelin sheath of the brain and spinal cord neurons is affected.

2. Myasthenia Gravis Affects Only Muscles While MS Can Affect Many Body Parts

Because myasthenia gravis specifically affects the communication between the nerves and muscles only, all symptoms have to do with muscle weakness. However, MS impacts a wider range of body systems, because the affected myelin sheaths are in parts of the brain and spinal cord that control the different parts of the body. As a result, people with MS may have issues with brain function, bladder control, and motor and sensory functions. The disease symptoms vary based on which part of the brain and spinal cord has MS plaques.

3. MG Treatments Focus on Nerve-Muscle Communications

The main goal of MS and MG treatment is suppressing aspects of the immune system responsible for autoimmune attacks. However, additional MG treatments include anticholinesterase medications to boost signals between the nerves and muscles. About 75 percent of people with myasthenia gravis have an abnormal thymus gland, which is an immune system organ. These abnormalities may lead to tumors that can become cancerous. As a result, thymectomy (surgery to remove the thymus) may be a recommended part of treatment.

Disease-modifying treatments (DMTs) for MS are focused on slowing the progression of the disease and reducing the frequency of attacks. People with MS may meet with different specialists to manage their symptoms.

Talk With Others Who Understand

On MGteam, the social network for people with myasthenia gravis and their loved ones, nearly 1,500 members come together to ask questions, give advice, and share their stories with others who understand life myasthenia gravis.

Have you been diagnosed with multiple autoimmune conditions? Or was your myasthenia gravis initially misdiagnosed because it resembled another condition? Share your experience in the comments below, or start a conversation by posting to your Activities page.