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Video Report

Displacement of the globe with chewing subsequent to reduction of a displaced fracture of the zygoma

Southampton Eye unit, Tremona Road, Southampton, UK

Correspondence: DrCrispin Malpas
Southampton Eye unit, Tremona Road, Southampton, SO16 6YD;
Email: crispinmalpas{at}hotmail.com Tel: 02380 777222; Fax: 02380 794120.

Date of acceptance: 27th February 2007

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Case Report

A 19 yr-old female was involved in a road traffic accident in which she was an unrestrained rear seat passenger.

She sustained a displaced fracture of her left zygoma and a fracture of her maxilla at the Le Fort level 1. Visual acuities were unaffected. The fractured zygoma was immediately reduced via a Gillies temporal approach and the maxillary fracture was reduced and plated via an intraoral approach. The patient made an uneventful immediate post-operative recovery.

She re-presented to the Ophthalmology department 1 year later with the sensation of objects in her vision 'jumping' when chewing. She did not complain of diplopia.

On examination visual acuity was 6/5 right and left. There was 1.5mm of enophthalmos on the left, with a deep upper lid sulcus. Eye movements were full. However, on movement of the jaw to the right the left eye was displaced superiorly. Subsequent CT scan showed connection of the temporalis muscle with the orbital contents. (Fig 1)

Figure 1: Axial CT showing connection between orbital contents and temporalis (White arrow)

The patient was offered surgery however she was not unduly troubled by her symptoms, was reassured, and discharged from the clinic.

Discussion

When the zygoma is fractured and displaced, the fracture passes through the suture between the greater wing of the sphenoid and the orbital plate of the zygoma in the lateral orbit. Fracture of the thin bone in the lateral orbit at this site may create a communication between the temporalis muscle in the adjacent temporal fossa and the orbital contents, in particular the periorbital fat and the lateral rectus muscle. In most instances unless there is gross disruption of the lateral orbital wall, formal reconstruction of the lateral orbit would not be carried out. It is thus theoretically possible for the temporalis muscle and the lateral orbital contents to become adherent as occurred in this case The fractured maxilla at Le Fort level 1 of course, would not involve the orbit in any way.

The most common approach to repair a fractured zygoma is the Gillies temporal approach.[1] This involves an incision within the hairline in the temple on the side of the fracture the incision passes through the skin and the underlying temporalis fascia. A zygomatic elevator is then placed under the temporalis fascia thereby passing under the zygomatic arch and body of the zygoma. The zygoma is then elevated to achieve a satisfactory reduction i.e. to return the zygoma to its pre-injury position. The zygoma is then either simply left in situ if stable following reduction, or plated to prevent displacement by the action of massetter muscle.

In this case, as can be seen on the CT scan (Fig 1), there is a connection between the temporalis muscle and the orbital contents. Hence when the temporalis is used in mastication the globe is displaced. Had the patient opted for surgical intervention this would have involved dissection via either a transconjunctival or transcutaneous approach to the orbital floor and lateral orbit, the adhesions between the periorbital tissues and the temporalis muscle would then be divided and a suitable barrier such as a thin sheet of silastic or bone graft would be interposed.

Complications of zygomatic fracture repair include malreunion, enophthalmos, diplopia, retrobulbar haemorrhage and injury to the orbital contents.[2] To the best of our knowledge mechanical displacement of the globe by the temporalis muscle following zygoma fracture repair is a previously unreported phenomenon.

References

• Larson OD, Thomsen M. Zygoma fractures. II. A follow-up study of 137 patients. Scand J of Plastic and Reconst Surg. 1978; 12(1): 59-63.
• Hirsch JM et al. A clinical evaluation of the Zygoma fixture: one year of follow-up at 16 clinics. J Oral Maxillofac Surg. 2004 Sep; 62(9 Suppl 2): 22-9.