Introduction
Marcus Gunn Phenomenon, also known as Marcus Gunn Jaw-Winking Syndrome, is a rare congenital disorder characterized by involuntary eyelid elevation (winking) associated with jaw movements such as chewing, sucking, or mouth opening. First described by Robert Marcus Gunn in 1883, this syndrome often presents with congenital unilateral ptosis.
Etiology and Pathophysiology
- Due to aberrant innervation between trigeminal nerve (CN V3) and oculomotor nerve (CN III).
- Miswiring results in simultaneous activation of levator palpebrae superioris muscle (eyelid elevator) with masticatory muscle actions.
Clinical Presentation
- Main Feature: Unilateral congenital ptosis improving or disappearing during jaw movement.
- Eyelid elevation ranges from subtle to pronounced.
- Typically noticeable from infancy.
Associated Conditions
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