198. Myasthenia Gravis Flashcards
What is myasthenia gravis?
The most common disorder of the neuromuscular junction, a chronic autoimmune disease resulting in antibody-mediated functional decrease in acetylcholine receptors.
What are the pathognomonic symptoms of myasthenia gravis?
Fluctuating skeletal muscle weakness exacerbated by activity and improving with rest.
What is the gender distribution pattern of myasthenia gravis?
Women are often affected in their third or fourth decade of life, while men are typically diagnosed in their sixth decade.
What antibodies are involved in myasthenia gravis?
Antibodies directed against the α-subunit of nicotinic acetylcholine receptors.
What is the typical age of onset for myasthenia gravis in women?
Third or fourth decade of life.
What is the typical age of onset for myasthenia gravis in men?
Sixth decade of life.
What is the initial diagnostic test for myasthenia gravis?
Short-acting anticholinesterase test, typically using edrophonium (Tensilon test).
True or False: In myasthenia gravis, deep tendon reflexes are typically absent or reduced.
False. Deep tendon reflexes are present.
What comorbidities are associated with myasthenia gravis?
Thymoma and small cell lung cancer.
What first-line treatment is commonly used for myasthenia gravis?
Acetylcholinesterase inhibitors, with pyridostigmine being the most commonly used.
Fill in the blank: Myasthenia gravis is characterized by a decrease in functional receptors by _______.
70%–80%.
What role does the thymus gland play in myasthenia gravis?
It is thought to be the origin of the autoimmune antibodies.
What is the effect of plasmapheresis in myasthenia gravis treatment?
It removes circulating antibodies from the bloodstream.
What should be avoided preoperatively in patients with myasthenia gravis?
Routine administration of sedatives, including barbiturates and opioids, to avoid respiratory depression.
What is the risk factor for ventilator dependence associated with myasthenia gravis?
Duration of illness > 72 months, daily pyridostigmine dose > 750 mg, vital capacity < 2.9 L, concomitant respiratory disease.
