Pathophysiology
This autoimmune disease is caused by antibodies that attack the postsynaptic acetylcholine receptors at the neuromuscular junction.
What is Myasthenia Gravis?
The most common initial symptoms of Myasthenia Gravis are typically related to the weakness of these muscles.
What are the extraocular muscles?
This autoimmune neuromuscular disorder is caused by antibodies attacking presynaptic voltage-gated calcium channels.
What is Lambert-Eaton Myasthenic Syndrome?
A serology report showing a positive result for _______ confirms the diagnosis of Myasthenia Gravis.
What are acetylcholine receptor antibodies?
This class of drugs is the first-line symptomatic treatment for Myasthenia Gravis.
What are acetylcholinesterase inhibitors?
first-line is Pyridostigmine, titrated to symptom relief
The primary target of the autoantibodies in Myasthenia Gravis is this receptor, which is a ligand-gated ion channel.
What is the nicotinic acetylcholine receptor?
In addition to muscle weakness, a key clinical sign is a drooping eyelid, known by this medical term.
What is ptosis?
In contrast to Myasthenia Gravis, this disease presents with muscle weakness that improves with initial exertion.
What is Lambert-Eaton Myasthenic Syndrome?
This electrophysiologic test, performed at a low frequency of 3 Hz, shows a characteristic decrement in a patient with Myasthenia Gravis.
What is a repetitive nerve stimulation study?
A patient presenting in a Myasthenic crisis requires immediate management with this type of treatment.
What are intravenous immunoglobulin (IVIg) or plasmapheresis?
An autoimmune process involving this gland is believed to be the source of the autoantibodies in a majority of patients with Myasthenia Gravis.
What is the thymus?
A patient presenting with a tired jaw while chewing and difficulty swallowing is exhibiting this type of weakness.
What is bulbar weakness?
This disease presents with a descending flaccid paralysis that begins with cranial nerve deficits.
What is botulism?
The absence of these two findings on the physical exam helps differentiate Myasthenia Gravis from a primary myopathy or a lower motor neuron disorder.
What are muscle atrophy and fasciculations?
This surgical procedure is often performed to induce remission in patients with Myasthenia Gravis who have thymic pathology.
What is a thymectomy?
The binding of autoantibodies to their target receptor at the neuromuscular junction ultimately leads to a failure of which physiological process?
What is muscle fiber depolarization?
This physical exam sign is an increase in muscle weakness after repeated or sustained contraction.
What is fatigability?
In a patient with muscle weakness, the presence of normal reflexes and no fasciculations helps to differentiate Myasthenia Gravis from this type of disorder.
What is a lower motor neuron disorder?
This follow-up imaging study is typically ordered when suspecting MG.
What is Chest CT?
-- indicated in all patients with confirmed myasthenia gravis to assess for a thymoma or thymic hyperplasia
What is a rare but life-threatening side effect of a common MG drug?
increased secretions and diarrhea - cholinergic crisis
Pyridostigmine
This phenomenon, characteristic of Myasthenia Gravis, results from the progressive decrease in acetylcholine receptor activation with each successive nerve impulse.
What is fatigability?
A patient reports that their symptoms of diplopia and muscle weakness are more pronounced in the evenings. This is an example of what kind of symptomatic fluctuation?
What is diurnal fluctuation?
Both Myasthenia Gravis and Lambert-Eaton Myasthenic Syndrome are paraneoplastic syndromes. What is the most common associated malignancy for each, respectively?
What are thymoma and small cell lung cancer?
This test is considered the most sensitive test for MG.
Bonus: indication? findings?
What is single-fiber electromyography (SFEMG)
The two primary immunosuppressive drug classes used to manage Myasthenia Gravis are ___ and ____