Is There Such A Thing As Bulbar Myasthenia Gravis?
Last updated: April 2023
Myasthenia gravis (MG) can have wide-reaching effects on the body. This can lead to different symptoms and ways of classifying MG.
One term that may be used is bulbar MG. This means MG that impacts the bulbar muscles, or jaw and throat muscles.
However, there is often confusion about whether bulbar MG is its own diagnosis or if it is a type of MG. Learning more about bulbar symptoms can help you understand what you are experiencing and get the right treatment.
What are the types?
Most experts agree that MG comes in 2 major forms: Ocular (related to the eyes) and generalized MG.1-3Ocular MG has symptoms that only affect the muscles that move the eyes and the eyelids. This can cause bulging of the eyes, double vision, drooping eyelids, and slowed eye movements.1-3
In generalized MG, several areas of the body are affected. Like ocular MG, the eye muscles are often involved. However, people with generalized MG may also have weakness of their arms, legs, the muscles that help move the chest during breathing, and more. It is possible for someone who initially only has ocular symptoms to progress to generalized MG.1-3
The weakness associated with both ocular and generalized MG can change over time. It may impact 1 side of the body, both, or switch sides. The weakness may have periods where it gets better and then worse. However, one thing that is unique to generalized MG is bulbar muscle involvement.
What are the bulbar muscles?
The term bulbar muscles refers to a group of muscles in the head and neck. These muscles are involved in speaking, swallowing, chewing, and holding the jaw in place. The nerves that control these muscles are located in a part of the brainstem called the bulbar region.1-4
If generalized MG affects this area of the brain, a person may develop bulbar symptoms. Other things can also affect the bulbar region of the brain and cause bulbar symptoms. This includes strokes, genetic conditions, and other autoimmune issues.1-4
What are the symptoms?
Because the bulbar area of the brain is impacted, symptoms are directly related to the nerves and muscles of this area. A person who has generalized MG that affects the bulbar muscles may notice their jaw muscles get tired, especially while eating.
This may happen in the middle of a meal or even when not eating at all. It is not uncommon for a person with MG with bulbar symptoms to support their jaw with their hands or fingers even when not speaking or talking.1,3
Other aspects of jaw movement are also affected. This includes problems swallowing and speaking. A person with bulbar symptoms may notice the pitch or strength of their voice changing. This can impact a person’s life dramatically.1,3,4
Being unable to swallow food or medicines can be dangerous. It can also lead to choking events called aspirations. This is when something that is swallowed goes into the lungs instead of the stomach. These aspirations can lead to infection or trouble with the lungs.1,4
It is also possible for someone with bulbar symptoms to have their swallowing impacted so much that they have liquids travel up through their nose. This may cause nasal regurgitation (leakage). The muscles of the face, including smiling or facial expressions, may also be affected in MG.
However, the area of the brain that controls these is not the bulbar region, so these are not technically considered bulbar symptoms.1,4
It is possible for a person to have mostly or only bulbar symptoms, especially at the very beginning of their MG. This happens more often in people with later onset MG (diagnosed later in life), though it is not common. However, even if a person starts with bulbar muscle issues only, they can still progress to have other muscle groups affected later on.1,4
Understanding generalized MG
While bulbar symptoms can be a major part of MG and can greatly impact a person’s life, they are part of generalized MG overall. While one person’s generalized MG symptoms can be very different from someone else’s, they all fall under the "generalized" umbrella.
Bulbar weakness outside of MG can have different causes and names. But when it comes to MG, bulbar symptoms are part of the larger generalized MG category and do not lead to a separate bulbar MG diagnosis.1-4
How often do you experience MG exacerbations/flares?