Myasthenia Gravis vs. MS

Medically Reviewed by Carmelita Swiner, MD on March 02, 2023
Written by Stefani McDade
4 min read

Multiple sclerosis (MS) and myasthenia gravis (MG) are both serious lifelong diseases. MS stems from faulty communication between your brain and the nerves that control your body. MG causes serious muscle weakness that can cause eyelids to drop and extend down to the rest of your face, arms, and legs.

Here are some other ways they’re alike, as well as how they might differ.

MS and MG happen when your immune system turns against your own healthy organs, tissues, and cells. That in turn disrupts the complex network of connections between your brain and your nerves and muscles.

With MS, the damage is in the myelin sheath that covers and protects your nerve fibers. With MG, your antibodies destroy the junction between your nerve and muscle cells.

Similarities. There’s no single proven factor that causes either MS or MG. Both conditions also:

  • Often affect those under age 40
  • Are more common in females. For MS, women outnumber men three to one. MG is much more common in younger women than in men
  • May be triggered by viral infections or other environmental risk factors

Differences. Some key contrasts include the fact that:

  • MS can run in families. But MG is generally not considered a hereditary condition. Most cases of MG might be caused by too much of certain antibodies produced by the thymus gland. In rare cases, newborns may have MG temporarily after their birth.
  • Whites are more likely to get MS than are Blacks or Asian Americans. But Black women are more likely to get MG compared with Black men and white men and women.
  • MS is more prevalent in areas such as North America with moderate climate, compared with warmer regions. A pair of recent studies found higher rates of MG cases in urban areas than in rural ones.

MS and MG often mimic each other because they involve similar issues in your body. The main one is inflammation.

The key symptoms of MS may include:

  • Feeling exhausted all over
  • Vision problems (optic neuritis, a condition that can decrease vision and cause eye pain) 
  • Trouble with balance and coordination
  • Tingling or prickling sensation
  • Difficulty with concentration or memory

Symptoms of MG may include:

  • Muscle weakness
  • Fatigue that affects specific areas of your body
  • Trouble moving your eyes or eyelids
  • Vision problems (double vision)
  • Difficulty swallowing, speaking, or making facial expressions due to muscle weakness

Many MG symptoms get worse with activity but may improve with rest.

Both MS and MG tend to worsen over time. And each can have periods when symptoms go away for a while and then return, often called temporary remission.

MS is often diagnosed after your doctor has ruled out all other possible causes. They’ll check your muscle reflexes, your vision and other senses, and ask about your symptoms. Other tests for MS may include:

  • MRI 
  • Eye exam
  • Blood screening
  • Spinal fluid check
  • Nerve test to check how quickly your brains responds to electrical stimuli

Tests for MG include:

  • Blood test to check for specific antibodies common in people with MG
  • Muscle reflex and strength
  • Nerve stimulation
  • Electromyogram to measure electrical activity in your muscles and nerves

There is no cure for MS or MG. Treatments for both may include certain prescription drugs or forms of physical therapy.

The main treatment goals with MS are to ease symptoms such as weakness and immobility, and to prevent or lessen the severity of relapses. Therapies for MG focus on strengthening your muscles to improve the message connection between your nerves and muscles.

Common therapies for MS include:

  • Disease-modifying treatments to slow disease progression. The FDA has approved more than a dozen of this type of drugs
  • Steroids to help with your attacks
  • Relaxants to calm muscle spasms
  • Medications to treat different side effects, including pain, itching, depression, tremors, and bladder problems

Treatments for MG may include:

  • Acetylcholinesterase inhibitor, a drug for MG that helps prevent enzymes that block nerve impulses
  • Glucocorticoids and nonsteroidal immunosuppressant drugs to tamp down your faulty immune response
  • Monoclonal antibodies, IV drugs that help fight attacks on your immune system
  • Surgery (thymectomy) to remove your thymus gland
  • IVIG, an infusion therapy that neutralizes and destroys damaging antibodies

Recent studies have found that in rare cases, people can have both MS and MG. Usually, a person may start with symptoms of MG but later show signs that mimic MS. Or it can happen the other way. If your doctor suspects this may be the case for you, they can use several different tests to find out for sure.