Marcus Gunn jaw winking synkinesis: report of two cases

Abstract

Marcus Gunn jaw winking synkinesis (MGJWS) is caused by congenital miswiring of a branch of the fifth cranial nerve into the branch of the third cranial nerve supplying the levator muscle. It has been observed in 2–13% of patients with congenital ptosis. Although bilateral cases were reported, most were unilateral and occurred more frequently on the left side than the right. We report two cases of children who presented with ptosis and were diagnosed with MGJWS.

Background

Marcus Gunn jaw winking synkinesis (MGJWS) was first described in 1883 as a unilateral ptosis with associated upper eyelid contraction and contraction of either the external or the internal pterygoid muscle. It is thought to occur because of congenital miswiring of a branch of the fifth cranial nerve into the branch of the third cranial nerve supplying the levator muscle.¹ In previous reports, MGJWS has been observed in 2–13% of patients with congenital ptosis, and although bilateral cases were reported, most were unilateral and occurred more frequently on the left side than the right.² Here we report the cases of two children who presented with ptosis and were diagnosed with MGJWS.

Case presentation

Case 1

The case was of a 4-month-old girl who presented to a paediatric neurology clinic with ptosis of the right eyelid. Her parents reported that ptosis was noticed within a few days after her birth. She was born at 40 weeks of normal pregnancy from non-consanguineous parents. She has no history of drug illness or orbital, facial or delivery trauma. A physical examination revealed that head circumference was 42 cm, height was 60 cm (25th percentile) and weight was 6500 g (55th percentile). On physical examination, it was noticed that rhythmic elevation of the right eye consistently occurred when the infant sucked on a pacifier. The eye completely elevated with each suck and returned to normal alignment between sucks (video  1).

Video 1

The right upper eyelid completely elevated with each suck and returns to ptotic position with the end of sucking.

Case 2

The case was of a 6-year-old girl. She presented with ptosis of the left eye. Her previous medical history was unremarkable. A neurological examination revealed rhythmic elevation of the left eye with lateral movement of the mandible (video 2). The rest of the examination was normal.

Video 2

The left upper eyelid completely elevated with lateral movement of the mandible and return to ptotic position with the end of movement.

Investigations

Ophthalmological examinations in both cases showed normal external, anterior segment and posterior segment structures. Laboratory investigations of both cases revealed that complete blood count, blood urea nitrogen, serum creatinine, liver function tests, fasting blood sugar, serum electrolytes, serum uric acid, lactate, pyruvate, ammonia, erythrocyte sedimentation rate, C reactive protein, thyroid function tests and urinalysis were within normal limits. Brain MRI of both the patients showed normal anatomy.

Differential diagnosis

Congenital ptosis.

Treatment

No surgical operation was considered in either case.

Discussion

In MGJWS, elevation and even retraction of the affected eyelid is triggered by chewing, suction, lateral mandible movement, smiling, sternocleidomastoid contraction, protruding tongue, Valsalva manoeuvre and even by breathing.³

Etiopathogenesis of MGJWS is not well defined. MGJWS is thought to occur from an abnormal branch of the trigeminal nerve, which has been congenitally misdirected in the oculomotor nerve supplying the levator muscle.^{3 4} The gestational age of the infant is not a predisposing factor for MGJWS. Koelsch and Harrington⁵ reported a full-term baby with MGJWS as in our case. However, premature patients have also been reported.^{4 6}

The necessity for correction of the jaw wink is determined by the parent, patient and surgeon. In many children, the ptosis improves with time, but there is no scientific proof that this really does take place. It is believed that, as time passes, the affected individual will come to recognise which movements are responsible for the synkinesis and learn to control or avoid them and thus minimise or mask the syndrome.^{2 7}

This report was carried out with the objective of alerting physicians to the existence of the MG phenomenon, which remains little known. In the differential diagnosis of patients with ptosis, MGJWS should be considered especially if it improves during feeding, sucking, chewing, smiling or any kind of mouth movement.

Learning point.

• In the differential diagnosis of patients with ptosis, Marcus Gunn jaw synkinesis should be considered especially if it improves during feeding, sucking, chewing, smiling or any kind of mouth movement.