Myasthenia Gravis

What is Myasthenia Gravis?

Overview

Myasthenia gravis (MG) is a chronic autoimmune disorder that affects the neuromuscular junction—the connection between nerves and muscles. In MG, the immune system mistakenly produces antibodies that interfere with the action of acetylcholine, the chemical messenger responsible for transmitting signals from nerves to muscles.

Normally, acetylcholine binds to receptors on the muscle surface and triggers a series of chemical and electrical reactions that allow the muscle to contract. When these receptors are blocked or damaged, communication is disrupted, leading to muscle weakness and fatigue.

Symptoms typically worsen with repeated activity and improve with rest, a hallmark feature of the condition. Myasthenia gravis is the most common disorder of the neuromuscular junction, though other rare conditions can also affect this communication.

Who is Affected?

Myasthenia gravis (MG) can affect people of all ages, but it is most commonly diagnosed in young adult women (under 40) and older men (over 60). While rare in children, it can occasionally appear in infants as neonatal myasthenia, usually passed temporarily from mother to child.

Myasthenia Gravis Symptoms & Causes

Symptoms

The symptoms of myasthenia gravis vary depending on which muscles are involved. The hallmark is muscle weakness that worsens with activity and improves with rest.

• Ocular/bulbar symptoms: droopy eyelids (ptosis), double vision (diplopia), difficulty speaking (dysarthria), difficulty swallowing (dysphagia), trouble chewing.
• Generalized weakness: arms, legs, neck, and facial muscles may become weak, especially later in the day or after sustained use.
• Respiratory weakness: in severe cases, breathing muscles can be affected, leading to a myasthenic crisis.

If the condition affects the whole body, it is called generalized myasthenia. If it primarily affects muscles of the eyes, face, and throat, it is called ocular or bulbar myasthenia.

Causes

The primary underlying cause of myasthenia gravis is the production of autoantibodies, specifically antibodies called acetylcholine receptor antibodies (AChR antibodies) or, in some cases, muscle-specific kinase (MuSK) antibodies. These antibodies target and bind to the acetylcholine receptors at the neuromuscular junction, interfering with the normal transmission of nerve impulses to the muscles. As a result, the muscles receive fewer signals, leading to weakness and fatigue.

When to See a Doctor

Seek medical attention if you experience:

• Persistent drooping eyelids or double vision.
• Sudden difficulty swallowing or speaking.
• Unexplained muscle weakness that gets worse with activity.
• Shortness of breath or difficulty breathing (call emergency services immediately, as this may indicate a myasthenic crisis).

Myasthenia Gravis Diagnosis

Diagnosis involves a combination of clinical evaluation, blood tests, and specialized studies:

Myasthenia Gravis Treatment & Outcomes

Treatment Options

One of the most important points in management is to avoid medications that can worsen myasthenia. In individuals with myasthenia, symptoms are usually manageable with a medication called pyridostigmine which increases the amount of acetylcholine available to muscles and helps overcome the fatigue and weakness.

While pyridostigmine can be very effective at reducing symptoms from myasthenia, it does not treat the underlying disorder.

For treatment of the underlying condition in patients who need rapid relief from bothersome symptoms, physicians can order IV gamma globulin infusions or, less commonly, a blood-filtering process (plasmapheresis) which is similar to dialysis.

For long term management, many patients need immunosuppressants (medications that reduce immune activity), such as prednisone, azathioprine, and mycophenolate.

Patient Outcomes

With modern treatments, most patients with myasthenia gravis are able to live active, fulfilling lives. While symptoms often fluctuate, long-term management with medications and supportive care greatly improves outcomes. A small percentage of patients experience severe, treatment-resistant disease, but prognosis overall has improved dramatically in recent decades.

Managing Myasthenia Gravis

Living with myasthenia gravis requires ongoing management and lifestyle adjustments:

Meet our Expert Specialists & Surgeons

William G. Buxton, MD

Adult Neurology

Experience Compassionate, Expert Care

At the Brain Health Center at Pacific Neuroscience Institute, our team is dedicated to providing personalized, multidisciplinary care for patients with myasthenia gravis.

From accurate diagnosis to advanced treatment and supportive therapies, we focus on maximizing independence, safety, and quality of life. We offer convenient access to specialists who provide compassionate, thorough clinical evaluations including electromyogram and nerve conduction studies. Infusion therapies are provided on site at our state-of-the-art neurodiagnostic and infusion suite in Santa Monica, CA.

Learn More About Myasthenia Gravis

Resources