Myasthenia gravis
Which of the following finding is usually associated with a diagnosis of Myasthenia Gravis?
A. Visual disturbances, including diplopia
B. Ascending paralysis and loss of motor function
C. Cogwheel rigidity and loss of coordination
D. Progressive weakness that is worse at the day’s end
Correct Answer: D. Progressive weakness that is worse at the day’s end
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Explanation :
– Visual disturbances, including diplopia : is incorrect because it refers to symptoms of multiple
sclerosis.
– Ascending paralysis and loss of motor function : is incorrect because it refers to symptoms of Guillain Barre syndrome.
– Cogwheel rigidity and loss of coordination : is incorrect because it refers to Parkinson’s disease
The client with myasthenia develops progressive weakness that worsens during the day.
Myasthenia Gravis – Important Points
Myasthenia gravis is an acquired Autoimmune disorder of neuromuscular transmission.
Cardinal clinical features
weakness of the eye muscles (called ocular myasthenia)
drooping of one or both eyelids (ptosis)
blurred or double vision (diplopia)
Muscle weakness after use of the affected muscle
Weakness in the arms, hands, fingers, legs, and neck.
Symptoms that are NOT expected in patients with myasthenia gravis
- Impairment of memory
- urinary incontinence
- numbness
- lack of sensation
Medical Treatment : Cholinesterase inhibitors
Main drug : Pyridostigmine
Surgical Treatment : Thymectomy
Myasthenic crisis – A medical emergency that occurs when the muscles that control breathing weakens and cause respiratory failure.
Cholinergic crisis – muscular weakness that can result when the dose of anticholinesterase drugsare too high.
Consider myasthenia gravis in patients with ptosis, diplopia, and muscle weakness after use of the affected muscle.
To confirm the diagnosis, measure serum levels of AChR antibody (usually present in myasthenia gravis), do electromyography (EMG), or both.
After the diagnosis is confirmed, test for thymic hyperplasia, thymomas, hyperthyroidism, and autoimmune disorders, which commonly accompany myasthenia gravis.
For most patients, use anticholinesterase drugs to relieve symptoms and immunomodulating treatment to slow disease progression and help relieve symptoms; do not use these treatments in patients with congenital myasthenia.
If patients have a myasthenic crisis, treat with IVIG or plasma exchange.
If patients suddenly deteriorate after responding well to treatment, provide respiratory support and stop anticholinesterase drugs for several days because they may have cholinergic crisis.
Question for You
You are educating a patient about the pathophysiology of myasthenia gravis. While explaining the involvement of the thymus gland, the patient asks you where the thymus gland is located. You state it is located?
A. Behind the thyroid gland
B. Within the adrenal glands
C. Behind the sternum in between the lungs
D. Anterior to the hypothalamus
Correct Answer is C : The thymus is located anteriorly in the upper part of the chest behind the sternum in between the lungs.
