From the Guidelines
Myasthenia Gravis (MG) is the disorder in which acetylcholine (ACh) receptor antibodies are produced against acetylcholine (ACh) receptors. In this autoimmune condition, the body's immune system mistakenly creates antibodies that attack and destroy the acetylcholine receptors at the neuromuscular junction, as described in the study by 1. These antibodies bind to the receptors, blocking acetylcholine from attaching to muscle cells or causing the receptors to be broken down more rapidly than normal. This interference with neuromuscular transmission results in the characteristic muscle weakness and fatigue seen in myasthenia gravis.
Key Characteristics of Myasthenia Gravis
- The antibodies specifically target the nicotinic acetylcholine receptors found at the postsynaptic membrane of the neuromuscular junction.
- About 85-90% of patients with generalized myasthenia gravis have these detectable antibodies, making their presence an important diagnostic marker for the condition, as noted in 1 and 1.
- Treatment typically involves medications that increase acetylcholine levels (like pyridostigmine), immunosuppressants, thymectomy, or therapies that reduce circulating antibodies such as plasmapheresis or intravenous immunoglobulin, as discussed in 1.
Management and Treatment
- Pyridostigmine bromide administered orally two to four times a day is the first line of treatment for myasthenia gravis, but about half of patients with strabismus-associated myasthenia show minimal response, according to 1.
- Corticosteroids have shown a positive response in about 66% to 85% of patients.
- Thymectomy is indicated in some cases, always in the presence of thymoma, and may substantially reduce symptoms for certain subpopulations with myasthenia gravis, as mentioned in 1 and 1.
From the Research
Myasthenia Gravis (MG) and Acetylcholine (ACh) Receptor Antibodies
- Myasthenia Gravis (MG) is a chronic disease causing muscle weakness, characterized by the production of antibodies against the acetylcholine receptor (AChR) 2, 3, 4, 5.
- Approximately 85% of patients with generalized MG and 50% of patients with purely ocular MG have anti-AChR antibodies 3.
- The presence of autoantibodies directed against the muscle nicotinic acetylcholine receptor (AChR) is the most common cause of myasthenia gravis (MG) 5.
- Autoimmune MG with AChR autoantibodies encompasses several disease subtypes defined by clinical presentation and thymic pathology 3.
Treatment of Myasthenia Gravis (MG)
- Treatment options for MG include thymectomy, cholinesterase inhibitors, immunosuppressive drugs, and plasma exchange or intravenous immunoglobulin 2, 3, 5.
- Pyridostigmine represents the first-line symptomatic treatment, while ambenonium and beta adrenergic agonists are second-line options 2.
- Combining corticosteroids at the lowest possible dose with azathioprine is recommended, rituximab being an alternative first-line option 2.
- Novel complement inhibitors and FcRn blockers are effective and fast-acting treatments with promising safety profiles 2.
- Acetylcholinesterase inhibitors (AChEIs) can provide symptomatic relief in AChR-antibody seropositive MG 6.