Myasthenia gravis Flashcards
What is MG?
Symptoms are characterised by muscle weakness, but muscles are fatigable, unlike in MND, suggesting dysfunction at the NMJ.
Autoimmune disorder - antibodies are produced against nACh receptors at the NMJ or against the MuSK protein, a RTK involved in NMJ development.
Treatable with ACEIs and immunomodulation.
Mechanism of disease
β-cells produce immunoglobulins against nAChRs, MuSK, and other proteins at the NMJ.
Prevents ACh release and muscle fibre depolarisation → reduced EPPs.
mEPPs also decrease → reduced storage of ACh in vesicles.
Degradation of neurojunctional folds.
Treatment
Edrophonium - cholinesterase inhibitor used in the diagnosis → does little in MND but causes temporary dramatic improvement in MG patients.
Neostigmine - cholinesterase inhibitor used as treatment
Immunosuppressants - corticosterone and prednisone - improve symptoms by suppressing antibody production.
Plasmapheresis removes antibodies from the circulation.
Removing the thymus gland rebalances the immune system.
Monoclonal antibody treatments target immune cells to reduce the production of autoantibodies - could be against the Fc receptor involved in the binding of autoantibodies to immune cells
