Myasthenia gravis (MG) is a long-term autoimmune disorder that leads to muscle weakness and tiredness. In autoimmune disorders, the immune system mistakenly targets healthy cells. In MG, it produces antibodies that interfere with nerve-muscle connections.
This condition can affect any muscle, but it usually impacts skeletal muscles, which are responsible for movements like breathing and using your arms and legs. To diagnose MG, healthcare professionals use a combination of tests such as blood, nerve, muscle, and imaging exams. Although there’s no cure at the moment, treatments are available to help manage symptoms and reduce medication side effects.
MG causes weakness in skeletal muscles, which worsens with activity and improves after resting. While any muscle can be affected, it commonly impacts muscles that control important functions. The onset of MG can happen suddenly, and people might experience varying degrees of muscle weakness along with other symptoms.
Muscle weakness from MG can target specific areas or affect multiple muscles. MG is categorized as either generalized or ocular. Transient neonatal MG is a temporary form impacting newborns. Generalized MG affects multiple muscle groups, and ocular MG only impacts eye muscles—it can be confused with conditions like stroke. Newborns with transient neonatal MG might show symptoms including muscle weakness shortly after birth, which usually subsides in a few days or weeks.
MG is an autoimmune issue targeting the junction where nerves meet muscles. The immune system produces antibodies that block nerve signals to muscles, leading to reduced muscle functionality and weakness.
In a healthy immune response, antibodies attack harmful invaders like bacteria or viruses. In MG, however, the immune system generates antibodies that disrupt the receptors for acetylcholine, a chemical used for nerve communication. As more receptors are destroyed, communication between nerves and muscles deteriorates, leading to weaker muscle contractions.
Some individuals might have additional antibodies targeting a different protein called muscle-specific kinase (MuSK), which further decreases acetylcholine receptors. While the exact cause of MG is still being studied, research shows a strong connection between MG and an enlarged thymus gland in about 75% of cases, which might send wrong signals to the immune system.
Diagnosing MG can be challenging due to its similarity to other health issues. Besides taking a medical history, healthcare providers may request various tests to confirm the diagnosis. This process can sometimes be lengthy. Patients are encouraged to advocate for their care, especially if muscle weakness symptoms are mild since diagnosis might be delayed by up to two years.
A myasthenic crisis is an acute episode of severe muscle weakness, often affecting breathing, and requires immediate medical attention. It can be triggered by stress, surgery, or infections and occurs in about 10% of people with MG.
Though there is no cure, MG is treatable. The focus of treatment is to lessen symptoms and manage medication side effects. Treatment plans are tailored based on symptom severity, affected muscles, and medical history. Options might include cholinesterase inhibitors like Mestinon, which aid in reducing muscle weakness symptoms, and immunosuppressive drugs if further intervention is needed.
For individuals who don’t respond to initial treatments, therapies like intravenous immunoglobulins (IVIG) and plasmapheresis provide short-term relief. IVIG helps temporarily protect the nerve-muscle junction from further damage, while plasmapheresis involves filtering harmful antibodies from the blood.
In some cases, MG might be linked to a thymus tumor. Removing the tumor and thymus can improve symptoms, except in ocular MG, where thymectomy is usually not recommended.
With effective treatment, most people with MG can lead normal lives. Advances in treatment and diagnosis have significantly reduced mortality rates related to myasthenic crises. Those living with MG can take steps to enhance daily life, including being aware of triggers like infections which can activate symptoms or a myasthenic crisis. Although more research is needed, studies indicate that vitamin D supplements might help reduce MG-related fatigue.
