Question:medium
A patient with ptosis presents with retraction of the ptotic eyelid on chewing. This represents:
A patient with ptosis presents with retraction of the ptotic eyelid on chewing. This represents:
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A trigeminal-oculomotor cross-wiring makes the drooping lid lift during jaw movement.
Updated On: Jun 24, 2026
- Marcus Gunn jaw-winking syndrome
- Third nerve misdirection syndrome
- Abducent palsy
- Oculomotor palsy
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The Correct Option is A
Solution and Explanation
The whole question hinges on one unusual link: an eyelid that normally droops but pops open the moment the patient works the jaw. That ties together two different cranial nerves. The trigeminal nerve drives the chewing muscles (the pterygoids), and a branch of the oculomotor nerve drives the levator palpebrae, the muscle that raises the upper lid. In Marcus Gunn jaw-winking, there is an abnormal congenital cross-wiring so that whenever the jaw muscles fire, say on chewing or moving the jaw to the opposite side, the levator fires along with them and the droopy lid jumps up. This trigemino-oculomotor synkinesis is exactly what the vignette describes. The other options do not fit. Aberrant regeneration of the third nerve produces odd lid or pupil movements linked to eye movements, not to chewing. An abducent nerve palsy simply weakens outward gaze. A plain oculomotor palsy gives a drooping lid with a down-and-out, dilated eye, but the lid does not retract when the patient eats. The only condition where chewing lifts the ptotic lid is Marcus Gunn jaw-winking syndrome. \[\boxed{\text{Marcus Gunn jaw-winking syndrome}}\]
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