Myasthenia Gravis Glossary

Understanding the Myasthenia Gravis Terms You Need to Know

Like many rare autoimmune diseases, Myasthenia Gravis (MG) has a unique language that can be overwhelming at first. Familiarizing yourself with these terms will not only help you better understand your condition, but will you to confidently communicate with your healthcare team.

Below is a comprehensive glossary of common words, medications, and treatments associated with MG, along with easy to understand meanings.

A

Acetylcholine (ACh)
A chemical messenger naturally produced in the body. Nerves release ACh to signal muscles to contract and move. (Cleveland Clinic)

AChR Antibody
AChR stands for acetylcholine receptor. These are the most common antibodies found in MG patients, interfering with the communication between nerves and muscles and causing weakness. (NINDS)

Acetylcholine Receptor Binding
Binding antibodies attach to the acetylcholine receptor, preventing proper nerve-muscle communication. (Mayo Clinic)

Acetylcholine Receptor Blocking
Blocking antibodies obstruct acetylcholine from binding to its receptor, impairing muscle activation. (NINDS)

Acetylcholine Modulating
Modulating antibodies alter receptor behavior, leading to degradation of the acetylcholine receptor. (Johns Hopkins Medicine)

Antibody
Proteins produced by the immune system to fight infection. In autoimmune diseases like MG, antibodies mistakenly attack healthy tissues. (Johns Hopkins Medicine)

Autoimmune Disease
A condition where the immune system attacks the body’s own healthy cells. MG is an autoimmune disease targeting the neuromuscular junction. (Mayo Clinic)

B

Bulbar Symptoms
Symptoms related to the bulbar muscles, including difficulty speaking, swallowing, and chewing, common in MG patients. (Cleveland Clinic)

C

CBC Differential
A detailed blood test that counts and categorizes different types of blood cells. Useful in monitoring MG-related health issues. (Mayo Clinic)

Central Line (Non-Tunneled)
A temporary catheter placed in a large vein to provide access for treatments like plasmapheresis or IVIG. (Johns Hopkins Medicine)

Central Line (Tunneled)
A more permanent catheter placed under the skin and into a large vein, often used for long-term treatments. (Mayo Clinic)

Cholinergic Crisis
A life-threatening condition caused by excessive doses of acetylcholinesterase inhibitors, leading to severe weakness, including in the breathing muscles. (NIH)

Clinical Trial
A research study designed to evaluate new treatments, drugs, or approaches for MG. (ClinicalTrials.gov)

Cortisol
A hormone that may be measured to assess stress and immune system function in MG patients. (NIH)

D

Diplopia
Double vision, often caused by weakness in the muscles that control eye movement. (American Academy of Ophthalmology)

Dysphonia
Difficulty speaking or changes in voice quality, such as sounding nasal or breathy, often seen in MG. (NIDCD)

Dysarthria
Slurred speech caused by weakness in the muscles involved in speaking. (Cleveland Clinic)

Dysphagia
Difficulty swallowing, a common symptom in MG due to weakness in throat muscles. (Johns Hopkins Medicine)

E

Exacerbation
A flare-up or worsening of MG symptoms, often requiring medical intervention. (NINDS)

F

Ferritin
A blood protein that stores iron, often measured to monitor health in MG patients. (Mayo Clinic)

FFP (Fresh Frozen Plasma)
A plasma product used in plasmapheresis to replace removed plasma. (Johns Hopkins Medicine)

Fibrinogen
A protein involved in blood clotting, which may be monitored during plasmapheresis or other treatments. (NIH)

G

Generalized MG (GMG)
The most common form of MG, involving weakness in multiple muscle groups, including the eyes, face, throat, arms, and legs. (Mayo Clinic)

I

IGA, IGG, IGM (Immunoglobulins)
Types of antibodies measured to assess immune function in MG patients. (NINDS)

IVIG (Intravenous Immunoglobulin)
A treatment where immunoglobulins are infused to neutralize harmful antibodies. (Mayo Clinic)

L

LRP4 Antibody
Antibodies targeting low-density lipoprotein receptor-related protein 4, which play a role in nerve-muscle communication. Found in some patients with seronegative MG. (NINDS)

Lymphocyte Subset Panel 7
A specialized test to measure immune cell subsets, providing insight into immune function. (Mayo Clinic)

M

MuSK Antibody
Antibodies targeting muscle-specific kinase, disrupting nerve-muscle communication. Often associated with a more severe form of MG. (Mayo Clinic)

Magnesium
A mineral that can affect muscle function and should be monitored in MG patients. (NIH)

Myasthenic Crisis
A life-threatening emergency where breathing muscles become severely weak, requiring immediate medical care. (Cleveland Clinic)

Myasthenia Gravis
An autoimmune disease where the body attacks the neuromuscular junction, leading to muscle weakness. (NINDS)

Magnesium
A mineral that may interact with neuromuscular function and is often avoided in excessive doses in MG patients. (NIH)

Vitamin D
A nutrient essential for bone and immune health, often monitored in MG patients due to its role in overall well-being. (Mayo Clinic)

N

Neonatal Myasthenia gravs (mG)
A temporary form of MG in newborns born to mothers with MG, resolving within weeks. (Johns Hopkins Medicine)

Neuromuscular Doctor
A neurologist specializing in disorders affecting the nerve-muscle connection, such as MG. (American Academy of Neurology)

Neuromuscular Junction
The site where nerves communicate with muscles to control movement, often targeted in MG. (NINDS)

P

Plasmapheresis (Plex)
A medical procedure that removes harmful antibodies and other immune system components from the blood, helping to reduce symptoms in autoimmune diseases like Myasthenia Gravis. During plasmapheresis, blood is drawn from the patient, plasma (the liquid part of the blood) is separated from the blood cells, and the harmful substances are filtered out. The filtered blood cells are then combined with replacement plasma or a plasma substitute, such as saline or albumin, and returned to the body. Plasmapheresis is typically used for severe MG symptoms or during a myasthenic crisis. It is often performed in a hospital or specialized outpatient facility (Mayo Clinic).

PLEX

commonly used as shorthand for plasmapheresis, originates from the phrase Plasma Exchange. It reflects the primary function of the procedure, where plasma (the liquid component of the blood) is "exchanged" by removing harmful substances, such as antibodies, and replacing the plasma with a substitute like fresh frozen plasma or saline/albumin. The abbreviation "PLEX" combines the first letters of "plasma" and "exchange" to provide a concise, easily recognizable term in medical communication.

Plasmapheresis and plasma exchange (PLEX) are often used interchangeably because they describe the same medical procedure. Both terms refer to the process of removing a patient’s blood, separating the plasma to filter out harmful substances (such as antibodies), and returning the blood cells mixed with a replacement fluid (like saline, albumin, or fresh frozen plasma).

• "Plasmapheresis" emphasizes the removal and processing of plasma.

• "Plasma exchange" highlights the exchange of the removed plasma with a substitute.

Clinically, both terms are synonymous and used based on preference or context, but "PLEX" is a shorthand term commonly used by healthcare professionals (Mayo Clinic)

Ptosis
Drooping eyelids due to weakness in the muscles that lift the eyelids. (American Academy of Ophthalmology)

Prednisone (Steroids)
A corticosteroid used to suppress the immune system and reduce symptoms in MG. (Johns Hopkins Medicine)

Port Access (For Plasmapheresis)
A specialized access point used for repeated plasmapheresis treatments. (Cleveland Clinic)

R

Refractory MG
A severe form of MG that does not respond to standard treatments. (NINDS)

Remission
A period when MG symptoms completely disappear, either with or without treatment. (Cleveland Clinic)

Robotic Thymectomy
A minimally invasive surgery to remove the thymus gland using robotic technology. (Mayo Clinic)

S

Seronegative MG
A subtype of MG where no detectable antibodies (AChR, MuSK, or LRP4) are found. (AANEM)

Spontaneous Remission

Spontaneous remission in Myasthenia Gravis (MG) refers to the unexpected and unexplained improvement or complete resolution of symptoms without the use of treatments or therapeutic interventions. This phenomenon is rare and is more commonly reported in certain subsets of patients, such as those with early or mild disease.The exact mechanism of spontaneous remission is not fully understood. It may involve the following: A natural decrease in autoantibody production, a Restoration of immune system balance, or a Reduction in thymus-related autoimmunity, particularly if the thymus undergoes age-related changes.(Myasthenia Gravis.com)

Thymus
A gland involved in the immune system, often dysfunctional in MG patients. (Johns Hopkins Medicine)

Thymectomy
Surgical removal of the thymus gland, a common treatment for some MG patients. (Mayo Clinic)

Thymoma
A tumor of the thymus gland, which can be benign or cancerous, often associated with MG. (Cleveland Clinic)

References and additional reading

1. Gilhus, N. E. (2016). Myasthenia Gravis. The New England Journal of Medicine, 375(25), 2570–2581. https://doi.org/10.1056/NEJMra1602678

2. Myasthenia Gravis Foundation of America. (n.d.). Common terms. Retrieved January 13, 2025, from https://myasthenia.org/What-is-MG/-Common-Terms

3. Myasthenia Gravis Foundation of America. (n.d.). Effects of MG on voice, speech, and swallowing. Retrieved January 13, 2025, from https://myasthenia.org/Community-Resources/MG-Materials-Webinars/Learn-More-About-MG/effects-of-mg-on-voice-speech-and-swallowing

4. Goldenberg, W. D. (2023). How is a cholinergic crisis differentiated from a myasthenic crisis in myasthenia gravis? Medscape. Retrieved January 13, 2025, from https://www.medscape.com/answers/793136-158060/how-is-a-cholinergic-crisis-differentiated-from-a-myasthenic-crisis-in-myasthenia-gravis

5. Jowkar, A. (2023). Myasthenia gravis. Medscape. Retrieved January 13, 2025, from https://emedicine.medscape.com/article/1171206-overview

6. HU Medical Review Board. (2021). Glossary of myasthenia gravis terms. Retrieved January 13, 2025, from https://myasthenia-gravis.com/glossary

7. Dresser, L., Wlodarski, R., Rezania, K., & Soliven, B. (2021). Myasthenia gravis: Epidemiology, pathophysiology, and clinical manifestations. Journal of Clinical Medicine, 10(11), 2235. https://doi.org/10.3390/jcm10112235