Overview
Patients with myaesthenic syndromes exhibit muscle fatigability, or the inability to maintain contraction of muscles over time.
Signs of Myaesthenia Gravis
Skeletal Muscle Fatiguability
- Simpson's test - ptosis on sustained upward gaze
- Peek sign - inability to maintain sustained eye closure
- Bulbar fatiguability - development of nasal speech with reading
- Proximal muscle fatigability - inability to maintain arms above the head
Signs of Management
- Thymectomy scar
Simpson's Test
How to Perform
- Ask the patient to sustain upward gaze over an extended period of time, and look for drooping of the upper eyelids.
Significance
- Patients with fatiguability secondary to myaesthenia will develop ptosis on sustained upward gaze.
Peek Sign
How to Perform
- Ask the patient to keep their eyelids closed for an extended period of time, and look for appearance of the sclera.
Significance
- In patients with myaesthenia, the sclera will become visible with prolonged eye closure due to fatigability.
Bulbar Fatigability
How to Perform
- Ask the patient to read a paragraph aloud.
Significance
- The progressive development of nasal speech while reading is suggestive of fatigability, a sign of myaesthenia.
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