Neonatal diagnosis of Marcus Gunn jaw-winking syndrome
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This male newborn was delivered at 39 weeks' gestational age by Cesarean section due to a failed trial of labor. At delivery, the Apgar score was 8 at 1 minute and 10 at 5 minutes of life. Birth anthropometry taken was as follows: weight 3560 gr (75th percentile), length 51 cm (75th percentile), and head circumference 33 cm (10th percentile). The boy was the first-offspring of unrelated healthy parents. Family history was negative for congenital malformations and disorders. Pregnancy was unremarkable.

At the initial full clinical examination performed soon after birth, left-eye ptosis was observed without evidence of edema. Namely, the newborn was hardly able to lift his left eyelid, whose opening was below the upper eyelid margin. Pupils were bilaterally isochoric, isocyclic, and reactive to light. Newborn's general appearance and clinical conditions were otherwise normal. No nervous system anomalies were detected. At 3 days of life, a first ophthalmologist evaluation was performed, and possible congenital ptosis was suspected. The red reflex test was normal. Brain sonography excluded abnormalities. The newborn was discharged at 4 days of life in good clinical conditions, with a follow-up program of the ptosis.

In the present case, at the follow-up ophthalmic visit the detection of abnormal left eyelid cooperation with uncoordinated opening/closing movements was noted, together with paradoxical synkinesis in swallowing during bottle-feeding. Based on these peculiar features, Marcus Gunn jaw-winking syndrome was diagnosed. Conversely, the inverse Marcus Gunn phenomenon was excluded. Indeed, in this rare congenital disorder, mouth opening (eg, while the individual is eating) induces or worsens eyelid drooping, due to an anomalous connection between the oculomotor and trigeminal nerves. Similarly, Marin-Amat syndrome, an acquired type of oculofacial synkinesis, was excluded as this rare condition is characterized by involuntary and fleeting eye closure when the mouth opens (eg, while the individual is smiling), due to an anomalous connection between the trigeminal and facial nerves. Lastly, Duane's syndrome, also known as Duane retraction syndrome, was not suspected because this ocular disorder is characterized by retraction movements and palpebral fissure narrowing when adduction is attempted, sometimes associated with down shoot and upshoot, and varying degrees of horizontal duction deficiency.

At the 4-month follow-up ophthalmic visit, no substantial improvements in the left-eye ptosis were detected. Physical growth and development were otherwise normal. A further follow-up visit was organized at the age of 8 months to assess the need and timing of corrective surgery.