Myasthenia gravis (MG) is an autoimmune neuromuscular disease that affects the muscles in the body. It is a chronic disease that causes certain muscles to become very weak when they are being used for a period of time, but return to normal strength after being rested.
The first signs of MG are usually slurred speech, problems swallowing, and weakness of the muscles around the eyes (ocular MG). Weakness in facial muscles can cause loss of eye control and eyelid movement, drooping of one eye, double vision, decreased ability to make facial expressions, and problems talking and chewing properly. Muscle weakness in the neck and chest can result in difficulty swallowing, breathing, speaking, and neck weakness. Other parts of the body that usually experience weakness include arms, hands, fingers, and legs.
In some instances, those with MG can experience "myasthenic crisis." This occurs when the respiratory muscles become paralyzed, requiring individuals to be put on breathing machines.
Myasthenia can be fairly mild and controlled with medication, or it can progress quickly to a disabling state. When myasthenia gravis begins to affect your muscles so much that you can no longer work, there are two ways you may be able to be approved for Social Security Disability (SSD) or SSI benefits: you meet the requirements of the disability listing for myasthenia gravis, for automatic approval, or Social Security agrees that MG is affecting your muscle function so much that you can no longer do "substantial gainful activity," or "SGA." (SGA generally means work that earns you more than about $1,200 per month.)
Myasthenia gravis has its own disability listing in the Social Security listing of impairments that may qualify for disability, called the blue book. To prove you meet the requirements of the MG listing, you must prove that you have myasthenia gravis and one of the following:
Marked means seriously limiting; it's worse than moderate, but less than extreme.
Proving MG can be difficult because muscles at rest do not generally have significant noted weakness. For this reason, it's important that your doctor brings your muscles to fatigue during testing and records the progressive weakness of your muscles. In addition, some patients with MG have lengthy periods of remission followed by exacerbations. However, Social Security is aware that MG can be episodic, so it will consider the frequency and duration of exacerbations and how long periods of remission last.
Medical evidence that may be used to fulfill the requirements of this listing includes electrical impulse machines to stimulate muscles to show weakness, pulmonary function tests to measure breathing, muscle biopsies, and physical examinations using physical endurance tests, leg raises, and/or grip strength tests.
Some patients with MG will not meet the criteria in the above MG listing because they don't have problems talking, swallowing, or the doctor hasn't recorded weakness in their arms or legs that Social Security considers significant enough. These patients may nevertheless have limitations that prevent them from successfully returning to work and being able to work enough to earn at least $1,200 per month.
Social Security will review your medical record for limitations that your doctor has documented and will gather them into a Residual Functional Capacity (RFC) assessment. Your RFC shows which work activities and jobs you have the ability to do, if any.
Due to muscle fatigue in the legs and/or arms, MG can limit any type physical activity. Specifically, if you have weakness in your legs, it makes walking or standing for long periods of time difficult, which would limit you to sedentary work. Weakness in your arms, hands, or fingers make completing tasks using your fingers difficult, which could rule out any sedentary work or at least light or medium work requiring lifting or carrying items.
If MG has affected your eyesight or your speech, this rules out many jobs that require good vision or communication, such as working with machinery, driving, working with others, and so on.
With MG, patients can often do some work, but need frequent rest breaks due to their easy fatigability. If you can complete some tasks required by a job, but your productivity is decreased by 20% or more due to your MG, Social Security is supposed to grant you disability benefits. You should record how easily your muscles are fatigued by keeping an activity diary, where you take notes on how many minutes of an activity, including speaking, weakens you muscles, and submit it to Social Security with your application or appeal. (For more information, see our article on qualifying for disability due to reduced productivity.)
After your RFC assessment, Social Security decides whether, given the work activities that your RFC says you are limited to doing, there are any jobs you can be expected to do, also taking into account your job experience, education, and age. For information on how the agency makes this decision, see our article on how Social Security uses the RFC to decide if you can work.