Myasthenia Gravis (MG)

     Myasthenia Gravis (MG) is a neuromuscular junction disorder caused by an autoimmune process, leading to severe muscle weakness. The weakness increases with exertion and improves with rest.

Mechanism

     The brain sends commands via nerves to the neuromuscular junction. At this junction, the nerve releases the neurotransmitter 'Acetylcholine' into the gap to trigger muscle contraction.

Cause of Myasthenia Gravis

     MG is caused by the thymus gland mistakenly producing Acetylcholine Antibodies. These antibodies destroy or block the Acetylcholine receptors on the muscle cell membrane. The resulting shortage of functional receptors means the muscles cannot receive enough Acetylcholine to contract properly, leading to weakness.

Who is Affected?

     MG can affect people of any age or race, including newborns. It is more common in young women and older men.

Symptoms of Myasthenia Gravis

Patients typically present with:

• Droopy eyelids (ptosis) and double vision (diplopia).
• Weakness in limb muscles and chewing muscles.
• Difficulty swallowing (dysphagia).
• Speech difficulties (nasal voice) due to muscle weakness.
• Shallow breathing and difficulty taking a deep breath.
• Trouble coughing.

Diagnosis

Doctors start with a patient history and physical exam. If MG is suspected, additional tests may include:

• Electromyography (EMG) and Nerve Conduction Studies.
• Blood tests for Acetylcholine receptor antibodies or other related antibodies.

Treatment

Treatment is customized to the patient's symptoms and may involve several methods:

• Medication: such as immunosuppressants and corticosteroids.
• Plasmapheresis (Plasma Exchange): to rapidly filter antibodies from the blood plasma. This is highly effective for severe, acute weakness.
• Thymectomy: can alleviate symptom severity, though the full effect may take 1-2 years to be noticeable.