Nasoethmoid Region ( Fig. 3.5.3 )

The nasoethmoid skeleton consists of the confluence of orbital, nasal, maxillary, and cranial bones. Multiple facial buttresses support the nasoethmoid region, including the frontal process of the maxilla vertically and the supraorbital and infraorbital rims horizontally. Together these buttresses create a relatively stable anterior framework. Weakness exists posteriorly in the form of the thinner lacrimal and ethmoid bones of the internal medial orbital walls, which are prone to blow-out fracture and comminution. The inadequate reduction of displaced medial orbital rim and wall fragments results in a loss of definition of the naso-orbital valley. This may require wide scar release during delayed or revision surgery while taking care to avoid iatrogenic injury to the medial canthal tendon. Soft tissue buttressing may then be required for recontouring in secondary nasoethmoid fracture repair ( Fig. 3.5.4 ).

Nasoethmoid region osseous components: (1) nasal process of frontal bone; (2) nasal bones; (3) nasal process of maxilla; (4) lacrimal bone; (5) lamina papyracea; (6) lesser wing of sphenoid bone. The key central bone fragment is shaded.

(Reproduced with permission from Resident Manual of Trauma to the Face, Head, and Neck. A publication of the American Academy of Otolaryngology – Head and Neck Surgery Foundation. Alexandria, VA; 2012.)

Normal naso-orbital surface anatomy. The naso-orbital valley displays complex and multidimensional surface anatomy. This is distinguished by a delicate soft tissue–bony interface where millimeters can make a significant difference in appearance.

(Courtesy Caleb M. Steffen, MD; Chattanooga, TN.)

Interorbital Space

Between the two medial orbital walls and below the floor of the anterior cranial fossa lies the interorbital space, which consists of two ethmoidal labyrinths divided by the perpendicular plate of the ethmoid and nasal septum. Anterior to this region are the nasal bones, and care must be taken to avoid confusing fractures of these bones with those of the nasoethmoid region. The cribriform plate is found in the posterior roof of the interorbital space, which explains the occasional occurrence of persistent cerebrospinal fluid rhinorrhea or dysosmia with delayed nasoethmoid fractures. The interorbital space is both vulnerable to fracture from central midface trauma and adds complexity to the accurate diagnosis of nasoethmoid fractures, which may contribute to delays in presentation.

Medial Canthal Tendon and Central Bone Fragment ( Fig. 3.5.5 )

The single most important region of the medial orbital rim to optimal surgical repair of complex nasoethmoid fractures in both the acute and delayed setting is the “central bone fragment,” into which the medial canthal tendon inserts. There are three limbs of the medial canthal tendon. The anterior limb is distributed over the frontal process of the maxilla onto the posterolateral nasal bones. The superior limb inserts at the junction of the frontal process of the maxilla and the internal angular process of the frontal bone. The thin posterior portion inserts behind the lacrimal sac into the posterior portion of the lacrimal fossa. Nasoethmoid orbital fracture lines may extend through the frontal process of the maxilla, the medial orbital wall, inferior orbital rim, and lateral nasal bones, resulting in a mobile central medial orbital rim fragment. This can result in a mobile canthal-bearing segment, which can compromise the integrity of eyelid support ligaments and the contour of the palpebral fissure. The degree of displacement is often proportional to the extent of comminution, which varies greatly between injuries. An intimate knowledge of these anatomical relationships is essential to appropriately manage secondary nasoethmoid fractures, whose premorbid anatomy must be reapproximated despite being altered at the time of presentation ( Fig. 3.5.6 ).

The key structures of the nasoethmoid orbital fracture. Central bone fragment is shaded bilaterally. The insertion of the medial canthal tendon into this bony segment can be seen.

(Courtesy Alina Sholar, MD; Austin, TX; reproduced with permission from Sargent LA. Nasoethmoid orbital fractures: diagnosis and treatment. Plast Reconstr Surg 2007;120(7):16S-31S.)

Displaced nasoethmoid fracture plated in nonanatomical position. Persistent abnormalities can be caused by inadequate reduction of the primary defect, as shown in this medial bone fragment malpositioning.

(Courtesy Alina Sholar, MD; Austin, TX; reproduced with permission from Sargent LA. Nasoethmoid orbital fractures: diagnosis and treatment. Plast Reconstr Surg 2007;120(7):16S-31S.)

Patient History

The delayed presentation of nasoethmoid fractures may occur after missed diagnosis or inadequate treatment of an acute injury, so the presentation may share certain elements of the original trauma setting with some important distinctions. The astute clinician should be mindful of the varied manner in which delayed nasoethmoid fractures may present in order to avoid repeating its misdiagnosis or inadequate treatment. A recent history of blunt trauma to the central midface is the typical presentation of the acute nasoethmoid fracture, but initial injury sequelae may not prompt presentation for weeks to months. Ideally, details of the original mechanism of injury and initial surgery would be obtained prior to any remote operative intervention. Without adequate primary nasoethmoid fracture repair, patients present with a variety of deformities, which are summarized in Box 3.5.2 .

Physical Examination ( Fig. 3.5.7 )

Physical examination findings of medial orbital rim step-off, mobile medial orbital bone segments, a “telescoped” nasal radix, or telecanthus may be obscured by central midface scar tissue or chronic edema. Common orbital findings in the representation of patients with nasoethmoid fractures include: an asymmetric corneal light reflex, displaced and misshapen bony fragments creating step-offs, enophthalmos, or periorbital soft tissue scarring and contracture. Due to lost nasal and septal support, the nose may appear flat and foreshortened with a wide nasal dorsum and upturned tip. Nasal deformity as a result of healed nasal bone fractures must be distinguished from the nasoethmoid deformity. Lacrimal dysfunction from a traumatized nasolacrimal duct may manifest with epiphora. The physical exam findings may reflect displaced bone fragments ( Fig. 3.5.8 ).

Submental view assessment of enophthalmos.

(Reproduced with permission from Edward Ellis III, Marcelo Figari, Gregorio Sánchez Aniceto, Kazuo Shimozato, Daniel Buchbinder, editors. AO Surgery Reference: Craniomaxillofacial Section. https://www2.aofoundation.org/wps/portal/surgery?showPage=diagnosis&bone=CMF&segment=Overview .)

Examination for orbital dystopia.

(Reproduced with permission Edward Ellis III, Marcelo Figari, Gregorio Sánchez Aniceto, Kazuo Shimozato, Daniel Buchbinder, editors. AO Surgery Reference: Craniomaxillofacial Section. https://www2.aofoundation.org/wps/portal/surgery?showPage=diagnosis&bone=CMF&segment=Overview .)

Individualized Operative Planning

Once secondary nasoethmoid deformities have been detected, an individualized treatment plan must be made to address each patient’s specific problem while omitting unnecessary surgical interventions. For example, inadequate nasal projection may require cantilever bone grafting, while a foreshortened nose may call for lengthening of the nasal lining, and each of these conditions may or may not be accompanied by an overlying soft tissue derangement that may require its own specific intervention. Enophthalmos requires orbital reconstruction, while a blunted canthal region may require medial canthopexy. Increased interorbital distance often requires medial orbital osteotomy prior to repositioning of bone fragments, perhaps even with slight overcorrection to compensate for expansion due to scarring. The role of the nasoethmoid region in determining orbital relationships cannot be overestimated. Whether due to displacement of the medial orbit or medial canthal tendon or due to an abnormal relationship between orbits from inadequate bony or soft tissue reduction, special attention must be paid to orbital symmetry during secondary nasoethmoid reconstruction.

Traumatic Telecanthus

The assessment and measurement of traumatic telecanthus is a skill that must be honed to ensure the accurate treatment of secondary nasoethmoid fractures. Telecanthus refers to an abnormally increased distance between the medial canthi and differs from orbital hypertelorism, which refers instead to an increased interpupillary distance or bony interorbital distance (dacryon to dacryon). Calipers may be used to measure intercanthal and interpupillary distances, which average 30–31 mm and 60–62 mm in a typical adult, respectively. Telecanthus becomes noticeable at varying distances, since the interpretation is relative to other facial structures, but distances greater than 40 mm are typically an indication for operative intervention.

Enophthalmos

Subtle variations in the degree of ocular projection may go unnoticed and do not require intervention when asymptomatic. Enophthalmos becomes noticeable when greater than 3–4 mm, which indicates the possibility of improvement by surgical management. Enophthalmos is measured from the lateral orbital rim to the anterior border of the cornea with a Hertel exophthalmometer. If the lateral orbital rim is also malpositioned, then a Naugle exophthalmometer may be used, which uses reference points above and below the superior and inferior orbital rims, respectively.

The preoperative consultation should include a discussion of reasonable expectations for outcome. Photographs predating the original injury may help guide the reconstruction, although they must be viewed in the context of the delayed nasoethmoid repair setting. An anticipation of a restored perfect premorbid appearance must be tempered to the actual goals of symmetry, correction of any obvious deformity, and relief of the patient’s symptoms.

Virtual Surgical Planning

Three-dimensional computerized planning may be employed in the virtual environment or physical models may be generated for operative planning and visualization prior to repair of secondary nasoethmoid fractures. However, unlike other secondary craniomaxillofacial deformities, which might feature larger bony structures amenable to individualized custom implant reconstruction or custom cutting guides, the fine anatomy of the nasoethmoid region requires meticulous repair of native tissue. Therefore, the benefit of virtual planning is largely for the surgeon’s preoperative visualization of the intended reconstruction. However, 3D models are beneficial in analyzing the displaced or deformed medial orbital wall segments as well as planning osteotomies.