Nasoethmoid orbital fractures, Naso-orbito-ethmoid fractures, NOE fractures
The Naso-orbital-ethmoid (NOE) region is the region lateral to the nasal bones and medial to the medial canthus. NOE fractures involve the lower 2/3 of the medial orbital rim, where the medial canthal tendon inserts. The classic NOE fracture pattern involves fractures of the lateral nose, the inferior orbital rim, the medial orbital ethmoid wall, the nasal maxillary buttress at the pyriform aperture, and the junction of the frontal process of the maxilla with the internal angular process of the frontal bone. Though this is the classic fracture pattern, significant variation exists. Markowitz classified NOE fractures into three types based on the relationship of the medial canthal tendon to the fracture lines and resulting bone fragments. NOE fractures may be unilateral or bilateral.
Figure 1 (naso-orbital ethmoid_fig1.tif): bony anatomy of the naso-orbital ethmoid region
Figure 2 (naso-orbital ethmoid_fig2.tif): relationship of the naso-orbital ethmoid complex to the medial canthal tendon and lacrimal apparatus
Figure 3 (naso-orbital ethmoid_fig3.tif): Markowitz Type I naso-orbital ethmoid fractures result in a single bone fragment into which the medial canthal tendon inserts
Figure 4 (naso-orbital ethmoid_fig4.tif): Markowitz Type II naso-orbital ethmoid fractures result in multiple bone fragments, though the fractures do not extend into the area of the attachment of the medial canthal tendon
Figure 5 (naso-orbital ethmoid_fig5.tif): Markowitz Type III naso-orbital ethmoid fractures result in numerous bone fragments, and importantly, the fracture lines extend through the bone into which the medial canthal tendon inserts, disrupting the medial canthal tendon. In this case, canthal avulsion may be present.
NOE fractures are generally the result of blunt-force trauma to the midface. Common causes include motor vehicle accidents, interpersonal altercations, assaults, falls, and sports-related injuries.
Facial fractures often occur as the result of significant trauma and evaluation should begin with airway control and hemodynamic stabilization. Spinal cord injury should be ruled out, and any overt globe injury should be evaluated. A thorough history and physical, including a complete head and neck exam, may then be performed. With any midfacial fracture, suspicion for CSF rhinorrhea and/or otorrhea should be high.
The NOE area plays a key role in midfacial contour and nasal projection and has important relationships to surrounding soft tissue structures that influence the clinical signs of an NOE fracture. Patients with NOE fractures may present with a short and sunken nasal bridge. Step-offs may be palpable along the nasal dorsum or medial orbital rim. Crepitus may often be felt over the medial canthus. The medial canthal tendon splits to envelop the lacrimal sac and attaches to the anterior and posterior lacrimal crests, frontal process of the maxilla, and internal angular process of the frontal bone, and plays a key role in supporting the globe and eyelid. When the medial canthal tendon attachment is disrupted, the medial canthus retracts laterally leading to an increased intercanthal distance and shortening of the palpebral fissure; an intercanthal distance of greater than 35 mm is suggestive of NOE fracture and a distance of greater than 40 mm is virtually diagnostic. The lacrimal system may be disrupted by NOE fractures and injury to the lacrimal canaliculi can result in epiphora. The trochlea is located on the internal angular process of the frontal bone and injury may cause extraocular muscle disturbance and diplopia. Patients may present with severe epistaxis either from Keisselback’s plexus anteriorly, or branches of the sphenopalatine or anterior ethmoid arteries posteriorly. Bleeding from the ethmoid vessels can also cause periorbital ecchymosis. Significant facial edema is common, and it is important to keep in mind that presence of a NOE fracture does not rule out presence of additional maxillofacial injuries.
NOE fractures involve orbital wall fractures, and a complete ophthalmic exam is necessary. Intracranial injury must also be ruled out, and suspicion for CSF rhinorrhea should be high. CT scan is considered the modality of choice for diagnosis of NOE fractures.
Treatment of ocular and CNS injuries should precede treatment of NOE fracture in the presence of a stable airway. In patients with multiple facial fractures, most authors advocate repair of associated facial fractures prior to repair of NOE fractures. Reduction of maxillary and frontal fractures can restore important landmarks that are used to guide repair of the NOE fracture. A combination of incisions may be required to gain adequate exposure. Commonly employed incisions include bicoronal, lynch, inferior orbital rim, subciliary, transconjunctival, and sublabial. When possible, existing lacerations should be used to gain access. Repair of NOE fractures should reposition the displaced bony fragments with reattachment of the medial canthal tendon if needed. Peri-operative antibiotics should be strongly considered in patients with facial fractures.
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3. Papel ID. (2002) Facial Plastic and Reconstructive Surgery, 2nd edn. Thieme, New York, pp754-758.
Stewart M. (2005) Head, Face and Neck Trauma, Comprehensive Management. Thieme