Myasthenia Gravis Flashcards
Definition of Myasthenia Gravis
Myasthenia gravis is a chronic autoimmune disorder that affects the neuromuscular junction, resulting in muscle weakness and fatigue.
It is caused by antibodies targeting specific proteins, such as the acetylcholine receptors (AChR) or muscle-specific kinase (MuSK), impairing the transmission of nerve signals to the muscles.
Causes of Myasthenia Gravis
Combination of genetic and environmental factors.
The production of autoantibodies, which attack the proteins at the neuromuscular junction, is thought to be triggered by an immune system malfunction.
In some cases, myasthenia gravis is associated with other autoimmune disorders, such as thyroid disease or rheumatoid arthritis.
Symptoms Myasthenia Gravis
Muscle weakness that worsens with activity and improves with rest.
The weakness can affect any voluntary muscle but commonly affects the muscles controlling eye and eyelid movements, facial expression, swallowing, and limb movements.
Symptoms include drooping of one or both eyelids (ptosis), blurred or double vision (diplopia), difficulty speaking, chewing, or swallowing (dysphagia), weak neck muscles, limb weakness, and respiratory muscle weakness in severe cases.
Diagnosis of Myasthenia Gravis
The presence of characteristic symptoms, such as fluctuating muscle weakness, can raise suspicion of the condition.
Blood tests to check for the presence of specific antibodies (AChR or MuSK).
Electromyography (EMG) to assess muscle activity.
Nerve conduction studies to evaluate the transmission of nerve signals to the muscles.
A repetitive nerve stimulation test may also be performed to detect muscle fatigue.
Treatment of Myasthenia Gravis
Cholinesterase inhibitors, such as pyridostigmine, can improve muscle strength by increasing the levels of acetylcholine at the neuromuscular junction. Immunosuppressive drugs, such as prednisone, azathioprine, or mycophenolate, may be prescribed to suppress the abnormal immune response.
Intravenous Immunoglobulin (IVIG): IVIG is a treatment option for severe cases or during exacerbations. It involves receiving high doses of immunoglobulins, which can temporarily modify the immune response and improve muscle strength.
Plasmapheresis: To reduce the levels of circulating autoantibodies and improve muscle function.
Thymectomy: If a thymoma (tumor of the thymus gland) is present or the thymus is abnormal, surgical removal of the thymus gland (thymectomy) may be recommended. This procedure can improve symptoms and reduce the production of autoantibodies.
Supportive therapies: Assistive devices such as eyepatches, glasses with prisms, and speech therapy may be used to manage specific symptoms like diplopia and dysphagia.
