Main

Sir,

The Marcus Gunn syndrome, described by Gunn in 1883, is one of the more common congenital oculofacial synkineses, and accounts for approximately 5% of all congenital ptosis.1

Typically, the infant is noted soon after birth to have a ptotic lid, which elevates spontaneously when sucking or chewing. The lid elevates on contraction of the lateral (external) pterygoid muscle, which mediates opening, forward, and contralateral movement of the jaw. Less commonly, the lid elevates upon closure of the mouth, which is mediated by the medial (internal) pterygoid. A very rare variant, ‘inverse’ Marcus Gunn syndrome is characterized by the lid falling on opening the mouth, because of inhibiton of the levator muscle in association with lateral pterygoid contraction. Although bilateral cases of classical Marcus Gunn are well documented, there are, to our knowledge, only two previous reports of a patient with the classical syndrome on one side and an inverse Marcus Gunn synkinesis on the other.1,2 This report describes the case of a 4 year-old boy with what could be described as ‘see-saw’ Marcus Gunn syndrome.

Case report

A 4-year-old boy, presented with a right congenital ptosis. His mother was concerned about the cosmetic appearance of the lid as well as anomalous movements of the lids when eating. The child was otherwise well, had no history of other ocular problems, and there was no family history of similarly affected individuals.

Examination showed his visual acuities to be 6/9 right 6/6 left. He had a 3–4 mm right ptosis, with typical Marcus Gunn syndrome on the right side, the lid elevating to the normal position with jaw opening. On the left side, the lid height was normal at rest, but became ptotic when the mouth was opened (Figure 1). There was no contraction of the orbicularis oculi. This resulted in the lids having a ‘see-saw’ motion with alternate opening and closing of the mouth. The voluntary levator function was right 3 mm left 10 mm. Ocular movements were full and there were no other abnormal findings on ocular nor general examination.

Figure 1
figure 1

(left) Right congenital ptosis and left lid in normal position with the mouth closed. (right) Reversal of lid positions with the mouth open. ‘See-saw’ Marcus Gunn syndrome.

Full size image

The child underwent bilateral extirpation of the levator muscle and frontalis slings with autogenous fascia lata as described by Crawford,3 with a satisfactory functional and cosmetic outcome (Figure 2).

Figure 2
figure 2

Postoperative appearance at 2 week.

Full size image

Comment

The Marcus Gunn syndrome is an interesting aetiological phenomenon. Electrophysiologic studies have documented cocontraction of the involved pterygoid and levator muscles in ‘typical’ cases,4 while one report documented inhibition of the levator muscle during ipsilateral lateral pterygoid contraction in a case of ‘inverse’ Marcus Gunn syndrome.5 Sano6 suggested, on the basis of electrophysiologic studies, that Marcus Gunn syndrome and other oculofacial synkineses represent release phenomena, as proposed by Pavesi et al.7 These phenomena are because of the reappearance of phylogenetically primitive synkinetic movements following injury to the involved cranial nerves in utero, with secondary degeneration of the cranial nerve nuclei. Cases may occur in isolation or in association with other anomalous ocular movements, such as double elevator palsy or Duane's syndrome,8 or with systemic anomalies such as cleft lip or palate. Bilateral cases have been reported in association with CHARGE syndrome.9 Such a heterogeneous group of patients suggests that the aetiologic mechanism is complex and that more than one factor is likely to be involved in the development of such synkineses.

This case adds further to the complexity, with the patient demonstrating the combination of both ‘typical’ and ‘inverse’ Marcus Gunn syndromes, that is, a positive synkinesis on one side and an apparent inhibitory synkinesis on the other, although the electrophysiologic basis of the anomalous movements was not investigated.

Inverse Marcus Gunn syndrome also needs to be distinguished from Marin Amat syndrome, where lid closure because of orbicularis oculi contraction is associated with mouth opening.1 Marin Amat syndrome generally follows seventh nerve palsy and is thought to be because of aberrant regeneration of the facial nerve. While some authors have used the terms ‘inverse’ Marcus Gunn syndrome and Marin Amat syndrome interchangeably, we believe the term inverse Marcus Gunn syndrome should be reserved for a congenital lesion, where lid closure is because of inhibition of the levator palpabrae superioris rather than orbicularis oculi contraction.

The treatment options in this case were more straightforward than in unilateral cases, as both lids required surgery to abolish the synkinesis and correct the subsequent ptosis. In this case, bilateral levator extirpation combined with frontalis suspension using autogenous fascia lata was successful in achieving the desired result.