Myasthenia gravis
Right ptosis due to myasthenia gravis showing fatiguability of the right lid on sustained upgaze

This is also called the Simpson test in which fatigure is observed on sustained lid and eye elevation.

There is a right partial ptosis. The pupils are equal in size. There may be limitation of ocular movement in any combination. The vertical muscles tend to be affected most. The limitation is variable and does not appear to correspond to any nerve palsy. On sustained upgaze, the right upper lid shows increased ptosis.

Perform the following:

  • Cogan's lid twitch sign = get the patient to rapidly refixate their eye from downgaze to the primary position, the sign is positive if there is overshooting of the upper lid before settling down to the ptotic position 

Animated pitcutre of a patient with right Cogan's twitch sign on rapid upgaze. Note the overshooting of the lid before settling down to the original ptotic level.
  • look for other signs of myasthenia gravis: thoracic scar from thymomectomy and weak voice.


1. During the Tensilon test, a patient collapses. How would you manage the patient?

2. How would you perform an ice pack test?

3. How are the differences between  myasthenia gravis and Lambert-Eaton's syndrome?

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