Management of a type II nasoethmoid orbital fracture and near-penetration of the intracranial cavity with transnasal canthopexy

Ear, Nose & Throat Journal, June, 2007 by Philip A. Young, Dale H. Rice

Abstract

Nasoethmoid orbital fractures are perhaps the most complicated aspect of craniomaxillofacial trauma. Involvement of the medial canthal tendon markedly increases the complexity of the repair We report a case of type II nasoethmoid orbital fracture in a 32-year-old man that was managed without formal medial canthal tendon repair; instead, we used open reduction and internal fixation of the central fragment and the nasoethmoid complex. However, during the immediate postoperative period, we noted anterior and inferior displacement of the medial canthus. We took the patient back to the operating room to address the detachment. Revision surgery was successful, and at the 6-month follow-up, his medial canthi were completely symmetrical in all dimensions. We describe our intraoperafive technique and measures to prevent complications that can help the surgeon intraoperatively. We also discuss an important point that has not been adequately addressed in the literature to date--that is, the fact that the use of the frontoethmoid suture line and the anterior ethmoid artery as a guide to the skull base can be inaccurate. Problems associated with this inaccuracy can be avoided by carefully reviewing preoperative computed tomography, which can help keep the surgeon from entering the intracranial cavity while fixing the medial canthal tendon during transnasal canthal repair

Introduction

A nasoethmoid orbital fracture is one of the most difficult fractures for the craniomaxillofacial plastic and reconstructive surgeon to treat. (1-5) Situated in the upper and central part of the middle third of the face, this type of fracture lies at the nasal, orbital, cranial, and frontal sinus junction.

Involvement of any of these areas can add to the complexity of the fracture repair. (6)

The nasal area is the weakest portion of the facial skeleton. (7) As force exerted against the nasal dorsum and root of the nose increases, the resulting trauma progresses from a simple septal fracture to involvement of the nasal bones. With more force, the fracture progresses to involve the thick glabellar bone, the frontal sinuses, and the medial and inferior orbital rims. Even more force results in involvement of the cribriform plate and the lamina papyracea, which provide relatively little resistance. (4,5)

The importance of adequate treatment of nasoethmoid orbital fractures has been well documented. (8,9) Consequences of inadequate treatment include (1) a gross deformity secondary to an obviously broad and abnormal nasal root with depression, (2) blunting of the medial canthus and the formation of an epicanthal fold, (3) a decrease in the palpebral aperture, and (4) an abnormal anatomic relationship with the lacrimal drainage system, which can result in epiphora. (10) The treatment of nasoethmoid orbital fractures has progressed from closed reduction and secondary treatment, which often led to poor results, to primary open reduction and fixation with plates and screws, which is now the gold standard.

The status of the medial canthal tendon and the central fragment is crucial to the diagnosis and treatment of nasoethmoid orbital fractures. (1,3) Managing the medial canthal tendon markedly increases the complexity of a nasoethmoid orbital repair. (1.2.6.7,9-14) Treatment of the medial canthal tendon has evolved from closed reduction, use of external bolsters, (7) interfragment wiring, (1) and tendon suturing (3,7) to transnasal canthopexy. Canthopexy requires that the surgeon pay meticulous attention to attaching the tendon to the posterior and superior portions of the lacrimal fossa, as described by Markowitz et al (1) and others. (2,3,7,11-14)

A number of classification schemes for nasoethmoid orbital fractures have been introduced, but the one developed by Markowitz et al (1) is perhaps the best known and most referenced. They classified nasoethmoid orbital fractures into three types:

* A type I fracture is characterized by the presence of a large, noncomminuted central fragment.

* A type lI fracture is a comminuted fracture in which both the central fragment of bone and the insertion of the medial canthal tendon are intact.

* A type III fracture is a comminuted fracture in which the fracture lines violate the central segment and markedly weaken the stability of the medial canthal tendon.

Transnasal canthopexy has probably become the gold standard for medial canthal tendon repair in nasoethmoid orbital fractures. However, if the central fragment has little bone left to which a plate can be sufficiently applied, we prefer detachment of the medial canthal tendon with refixation, using the combination of transnasal wiring and miniplates (interfragment wiring is less than ideal in such a situation). This can be accomplished without increasing the thickness of the nasal root, which some have suggested is a drawback to using miniplates. (1) An important consideration is that in some cases, even a minimal amount of dissection of the central fragment performed to accommodate a single microplate hole and screw is enough to weaken the medial canthal tendon to the point that it cannot support the medial canthus and the lower eyelid structures; even with transnasal wiring of the fragment, as suggested by Markowitz, (1) the tendon would be too unstable to provide proper support. Despite proper bony reduction of the central fragment, the soft tissues and the medial canthal tendon can be lax, leading to a cosmetic deformity or a less-than-ideal result. When in doubt, the medial canthus can be adequately repaired by (1) a full detachment of the medial canthal tendon with transnasal wiring, (2) wiring to a miniplate in proper position, or (3) a combination of the two, depending on the stability of the bone fragments.