Myasthenia Gravis Flashcards
what is Myasthenia Gravis
disorder of transmission @ neromuscular junction that affects communication between motor neuron & innervated muscle cell
Myasthenia gravis is a ___________ disorder characterized by
Autoimmune disorder characterized by varying degrees of weakness of the voluntary muscles
who is more frequently affected by myasthenia gravis? and at what age
Women
20-30yrs
after History and Physical exam what are the three primary tests to diagnose myasthenia gravis
anticholinterase test
nerve stimulation studies
blood test
anticholinterase test for diagnosing myasthenia gravis
anticholinesterase is an enzyme that destroys acetylcholine, to complete acnticholinesterase test, short term anticholinesterase inhibitor usually edrophonium (Tensilon) will be administered. If pt has MG there should be dramatic improvement of muscle functioning while on edrophonium
nerve stimulation studies for diagnosing myasthenia gravis
stimulates motor nerves with low frequency electrical energy in order to gauge muscular response. when impulse is generated, assessments will be made regarding delayed or failed transmission in nerve fibers & aid in diagnosis of MG.
blood test for diagnosing myasthenia gravis
in search of acetylcholine antibodies. These antibodies should not exist within our bodies and therefore can aid in a definitive diagnosis of MG
Patho for myasthenia gravis
antibodies directed at the acetylcholine receptor sites impair of impulses across myonerual junction. therefore fewer receptors are available for stimulation, resulting in voluntary muscle weakness that that escelates with continue
2 types of management for myasthenia gravis
- pharmacological immunosuppresion
- plasmapheresis
pharmacoligical immunosupression for management for myasthenia gravis
mainly reducing activity of immune system due to its autoimmune dysfunctions
ex corticosteriods or other immunosuppresants such as
plasmapheresis for management for myasthenia gravis
process that removes antibodies from bodys circulation. provides short term relief until new antiboides are created. Plasmapherisis will aid in managing MG as it will remove the harmful acetylcholine receptor antibodies thus allowing more precise neurotransmission. Plasmaphereisis also utilized in myasthenic crisis in order to stabilize patient,
what is myasthenic crisis
occurs when muscle weakness becomes so severe ventilation is compromised. respiratory muscle & bulbar weakness does not support inhalation nor airway clearance, resulting in respiratory compromise
what is myasthenic crisis caused by
may be caused by MG worsening or by a sepecific event such as respiratory infection, medication change, surgery or pregnancy
what interventions may need to be done for myasthenic crisis
endotracheal intubation & mechanical ventilation may be required to maintain patencey of the airway. In less serious cases positive pressure ventilation may suffice. Plasmapheresis & changes to patients drug regime will need to occur.
what normally happens at neuromuscular junction
normally chemical impulse precipitates the release of acetylcholine from vesicles on nerve terminal neuromuscluar junction. The acetylcholine attaches to receptor sites on the motor endplate & stimulates muscle contraction. continuous binding of acetlycholine to receptor site is required for muscular contraction to be sustained
