Myasthenia gravis

Injury	Disease	Nutrition	Poison

Symptoms	Surgery	Test	Special Topic

Superficial anterior muscles

Myasthenia gravis

Symptoms:

Vision changes:
- Double vision
- Difficulty maintaining steady gaze
- Eyelid drooping
Patients with generalized disease may also have:
- Swallowing difficulty, frequent gagging or choking
- Weakness or paralysis (may worsen with exertion later in the day)
- Muscles that function best after rest
- Drooping head
- Difficulty climbing stairs
- Difficulty lifting objects
- Need to use hands to rise from sitting positions
- Difficulty talking
- Difficulty chewing

Additional symptoms that may be associated with this disease:

Signs and tests:

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Examination may be normal or may show muscle weakness that progressively worsens as the muscle is used. In many patients the eye muscles are affected first. Reflexes and sensation are normal. Weakness may affect the arms, legs, breathing or swallowing muscles and any other muscle group.

Standard EMG results are usually normal. Repetitive stimulation (type of nerve conduction studies) are more sensitive.
Single-fiber EMG is even more sensitive.
Acetylcholine receptor antibodies may be present in the blood.
A Tensilon test is positive in some cases but must be interpreted carefully by an experienced doctor. Baseline muscle strength is evaluated. After Tensilon (edrophonium, a medication that blocks the action of the enzyme that breaks down the transmitter acetylcholine) is given, muscle function may improve.