This 6 year-old girl was referred by her family doctor because of the appearance in figure 1.
a. What is the diagnosis?Marcus-Gunn jaw winking syndrome.
The patient has a right ptosis but on stimulation of the ipsilateral medial pterygoid by moving the jaw laterally there is retraction of the upper lid.
b. What is the mechanism of this condition?It is caused by synkinetic innervation between the levator and the ipsilateral pterygoid muscle. This results from the misdirection of the fifth cranial nerve fibres to the levator which is normally innervated by the third cranial nerve. Consequently, when there is movement of the jaw muscle excess nerve impulse is conducted to the levator muscle causing lid retraction.
c. How would you manage this condition?It is important to assess the visual function and the refractive state as there is an increased incidence of strabismus and refractive error.
Surgical management is needed only if there were deprivation amblyopia otherwise the parents should be reassured about the benign nature of this condition and the tendency for the ptosis to improve with age.
Surgical management involve levator disinsertion of the affected side followed by bilateral frontalis suspension.
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