From the Guidelines
Myasthenia gravis is a group of B-cell mediated autoimmune disorders that profoundly affect activity at the neuromuscular junction, causing variable weakness exacerbated by fatigue, as described in the most recent study 1.
Definition and Pathophysiology
Myasthenia gravis (MG) is characterized by weakness and rapid fatigue of voluntary muscles, resulting from the immune system's attack on the communication pathway between nerves and muscles, specifically targeting acetylcholine receptors at the neuromuscular junction 1. This disruption prevents nerve impulses from triggering muscle contractions effectively. The term myasthenia gravis refers to a group of B-cell mediated autoimmune disorders that profoundly affect activity at the neuromuscular junction causing variable weakness exacerbated by fatigue.
Clinical Presentation
Common symptoms of myasthenia gravis include:
- Drooping eyelids
- Double vision
- Difficulty swallowing or speaking
- Weakness in the arms and legs that typically worsens with activity and improves with rest It can mimic many types of incomitant strabismus with or without ptosis, as noted in 1.
Treatment Options
Treatment options for myasthenia gravis include:
- Acetylcholinesterase inhibitors like pyridostigmine (Mestinon), which improve neuromuscular transmission by increasing acetylcholine availability
- Immunosuppressive medications such as prednisone, azathioprine, or mycophenolate mofetil to reduce the abnormal immune response
- Thymectomy (surgical removal of the thymus gland) may be beneficial for certain subpopulations with myasthenia gravis, as indicated in 1 Regular monitoring by a neurologist is essential, as medication dosages often need adjustment based on symptom severity and response to treatment.
Management and Referral
Diagnosis and management of myasthenia gravis require the training and clinical judgment of an experienced ophthalmologist typically working in concert with a treating neurologist, as emphasized in 1. Counselling and referral to a neurologist or neuro-ophthalmologist, and sometimes a general surgeon, is often indicated in the management of myasthenia gravis.
From the FDA Drug Label
Myasthenic crisis due to an increase in the severity of the disease is also accompanied by extreme muscle weakness, and thus may be difficult to distinguish from cholinergic crisis on a symptomatic basis
- Myasthenia Gravis (MG) is a disease characterized by increasing muscle weakness.
- The text does not provide a detailed definition of Myasthenia Gravis, but it mentions that myasthenic crisis is accompanied by extreme muscle weakness due to an increase in the severity of the disease 2.
From the Research
Definition and Characteristics of Myasthenia Gravis
- Myasthenia gravis (MG) is a chronic neuromuscular disorder characterized by fluctuating skeletal muscle weakness and fatigue 3
- It is an autoimmune disease that affects the postsynaptic membranes in neuromuscular junctions, presenting as fatigable muscle weakness 4
- MG can be classified based on the presence of serum autoantibodies, with acetylcholine receptor (AChR) antibodies found in 80%-85% of patients 5
Clinical Features and Diagnosis
- The most common symptoms of MG include ptosis, diplopia, facial bulbar weakness, and limb weakness 5
- Recognition of clinical features is a key component of prompt diagnosis, and advanced practice nurses (APNs) should be aware of variations in MG symptoms 3
- Diagnosis can be established with additional tests, including repetitive nerve stimulation, single fiber EMG, and the ice pack test 5
Treatment Options
- Treatment options for MG consist of symptomatic treatment (such as pyridostigmine), immunosuppressive treatment, or thymectomy 5
- Intravenous immunoglobulins (IVIg) and plasmapheresis (PLEX) are used to manage myasthenic crises, with the choice between them guided by individual patient characteristics and institutional resources 4
- Pyridostigmine is a commonly used treatment for MG, and is generally considered safe, but most patients eventually switch to long-term immunosuppressive therapies 6