Myasthenia gravis vs. MS: What’s the difference?

Myasthenia gravis (MG) and multiple sclerosis (MS) are both autoimmune disorders that can cause movement problems, fatigue, eye issues, and other symptoms.

Because several symptoms overlap, MG can be mistaken for MS. However, they are distinct conditions with different underlying causes, treatment needs, and long-term outlooks. Understanding how MG is different from MS will help patients know what to expect with their diagnosis and ensure they receive appropriate care.

Key differences at a glance

MG is like MS in several ways, but it also has several key differences. Both are autoimmune diseases in which the immune system mistakenly attacks a healthy part of the body, but the specific parts affected in MG vs. MS differ:

• MG: The immune system produces self-reactive antibodies that attack neuromuscular junction proteins important for nerve-muscle communication. This leads to symptoms of muscle weakness and fatigue.
• MS: The immune system attacks myelin, a substance that surrounds and protects nerve cells in the brain, spinal cord, and optic nerve at the back of the eye. This can lead to a wide range of possible symptoms, including muscle weakness.

A key difference between MS and MG is the disease course. MG symptoms fluctuate, getting worse with activity and easing with rest. While they are commonly most severe in the first few years, symptoms often stabilize or ease long-term.

At disease onset, MS usually involves unpredictable periods of symptom worsening (relapses) interspersed with symptom easing (remission). However, it is inherently a progressive disease, ultimately leading to the accumulation of disability over time.

Both MS and MG commonly affect young women in their 20s and 30s.

With modern treatments, MG life expectancy is relatively normal, while on average, MS life expectancy is about five to 10 years shorter than that of the general population.

Symptoms: How they overlap and differ

Some symptoms overlap between MG and MS, including:

• blurred or double vision
• muscle weakness and trouble walking
• speech and swallowing issues
• breathing difficulties
• fatigue

However, these symptoms often have different patterns or severities.

MG symptoms are characterized by muscle weakness that worsens with activity and improves with rest. Depending on the MG type, weakness may be restricted to the eyes (ocular MG) or be more generalized. Symptoms that are more common in MG than in MS include:

• eyelid drooping (ptosis)
• problems with chewing and swallowing
• slurred speech or other speech issues
• shortness of breath or other breathing issues

MS symptoms vary more widely than MG symptoms because several parts of the nervous system might be affected. Symptoms more common in MS than in MG include:

• numbness or abnormal sensations
• dizziness
• cognitive difficulties
• loss of bowel or bladder control
• sexual dysfunction
• mood problems
• walking, balance, and coordination problems
• muscle spasms

MS vs. MG muscle weakness differences can help differentiate the two diseases. While MG muscle weakness fluctuates, that in MS may progressively get worse over time. The muscles around the eyes, face, and throat are less commonly affected in MS, although issues with eating, speech, and breathing can occur in more advanced disease stages.

How doctors tell them apart

Diagnosing MG or MS relies heavily on a comprehensive medical history and symptom review, along with a neurological and physical exam. This will help doctors identify risk factors and symptom patterns unique to each disease.

Reaching an MG vs. MS diagnosis may thereafter require different diagnostic tests:

• MG: Blood tests to look for MG-causing antibodies are the most definitive way to diagnose the disease. Imaging tests to visualize abnormalities in the thymus gland — often linked to MG — and tests of nerve and muscle activity may support a diagnosis.
• MS: Doctors look at the collective results from MRI scans, blood and spinal fluid lab tests, and nerve signaling tests to identify hallmark patterns of inflammation and damage.

Treatment approaches

The treatment for MG and MS is distinct. There is no cure for either disease, but treatments can help slow progression, ease symptoms, and improve quality of life.

• MG: There are several treatment options for MG. They generally work to boost nerve-muscle signaling, suppress the immune system, or reduce the levels of self-reactive antibodies. In some cases, surgery to remove the thymus gland (thymectomy) may be of benefit.
• MS: Disease-modifying therapies work in different ways to prevent relapses and slow MS progression, usually by suppressing the immune system. Other medications, along with physical, occupational, and speech therapies, can also help ease specific symptoms, depending on the individual situation.

Regardless of the diagnosis, people with MG or MS require consistent follow-up with a neurologist and multidisciplinary care team. Supportive care approaches, like physical therapy, psychological support, and healthy lifestyle changes, are important for both conditions.

Daily life impact

Living with MG vs. MS can look different, but both conditions have a substantial daily life impact:

• MG: Because muscle weakness gets worse with use, people with MG may have a harder time doing daily activities like eating, driving, or household chores without needing rest. They may also worry about serious symptom exacerbations, like myasthenic crises that affect breathing.
• MS: Symptoms can have various daily life impacts. For example, movement problems may make performing daily activities independently more difficult, while cognitive problems can make it harder to concentrate at work. Individuals may worry about long-term progression and permanent disability.

People with both conditions may need to make lifestyle changes to conserve energy and make daily activities manageable. It may also require avoiding triggers that worsen symptoms.

Both conditions can strongly affect emotional well-being and social relationships. Living well with MG or MS relies on strong support systems and communication with the care team.