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Ophthalmic Pearls: Oculoplastics
Assessing the Subtleties of Medial Wall Fractures
By Caroline Rosenberg, MD, and Ioannis P. Glavas, MD
Edited by Ingrid U. Scott, MD, MPH, and Sharon Fekrat, MD
 
 

Isolated medial wall fractures are an underdiagnosed, but important, outcome of facial trauma. A large study documented that the medial wall is involved in 10 percent of facial fractures, and of these, only 10 percent are isolated medial wall fractures.1 The medial wall is often injured along with the orbital floor, although more complex injuries are also frequent. However, another smaller study showed that among pure blowout fractures, isolated medial wall fractures account for nearly 55 percent.2 Solitary medial wall fractures also can lead to significant sequelae, including enophthalmos and visual dysfunction. Early diagnosis of the fracture and subsequent treatment can improve the long-term outcome in these patients.

Anatomy

The medial wall is composed of the frontal process of the maxilla, the lacri-mal bone, the orbital plate of the ethmoid bone and the sphenoid body. The area damaged most easily by trauma is the particularly thin lamina papyracea, which separates the orbit from the ethmoidal sinuses. The lacrimal sac lies anteriorly along the medial wall in the lacrimal groove formed by the maxilla and lacrimal bone.

At the junction of the medial wall and orbital roof are the anterior and posterior ethmoidal foramina. Via these foramina, the anterior and posterior ethmoidal arteries and nerves course between the orbit and the anterior cranial fossa. These structures can be injured directly at the time of trauma, and care must be taken to avoid damaging them further during surgical repair.

In addition, the medial rectus muscle is intimately related to the medial wall. One of the most obvious signs of medial wall fracture is a motility disturbance, usually deficient adduction or abduction, caused by damage to or entrapment of the medial rectus. Entrapment of the medial rectus is a common indication for surgical repair. Other nearby, medially located structures that can be damaged along with the medial wall include the medial canthal tendon, the trochlea and the lacrimal drainage system.

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Diagnosis

Because isolated medial wall fractures are uncommon and their presentation is often subtle, diagnosis can be challenging. Many patients are asymptomatic or their symptoms may be obscured by coexistent orbital floor fractures.

Signs and symptoms. A history of trauma such as a fist blow directly to the naso-orbital region is commonly offered by patients with isolated medial wall fractures. More severe injuries such as the ones observed after falls or motor vehicle accidents tend to have concomitant orbital floor fractures.1 Patients will often have periorbital edema and ecchymosis, which may be the only obvious signs of injury. Damage to the globe is less common, but injuries can include subconjunctival hemorrhage, corneal abrasions, iris injury, commotio retinae, sclopetaria, vitreous hemorrhage, optic nerve injury and retrobulbar hemorrhage.

Some signs can be more specific to medial wall injury. For example, damage to the ethmoidal air cells may lead to subcutaneous emphysema of the eyelids, or epistaxis may result if there is associated vascular injury. Medial rectus injury or entrapment may be suspected if there is limited adduction or restricted abduction, which sometimes cause diplopia. However, diplopia does not always indicate medial rectus entrapment. Diplopia also can be caused by bleeding, edema, orbital fat incarceration, decompensation of phorias or cranial nerve injuries. Diplopia occurs more commonly with medial wall plus orbital floor fractures than with medial wall fractures alone. In addition, on attempted abduction, some patients may experience globe retraction. Later findings can include enophthalmos.

Patients can present with a “white-eyed” medial blowout fracture, in which the medial rectus is entrapped, causing extraocular movement disorders and diplopia but no other external signs of trauma. In the literature, a few articles show that children more commonly than adults present with this injury.3 These children can easily remain undiagnosed, but they should have early evaluation and often surgical correction to avoid permanent motility disturbances.3

Imaging. The diagnosis of medial wall fractures is confirmed with CT using coronal and axial planes. Traditional x-ray films are of little utility; at best, they elucidate fewer than half of subsequently proven fractures.1 A CT scan can measure the extent of the fracture, localize bony and foreign body fragments and visualize soft tissue injury. Almost 80 percent of isolated medial wall fractures are blown out with displaced bone fragments, while comminuted and linear nondisplaced fractures are much less common.1 In addition to bony abnormalities, CT scans may show air in the orbit, but ethmoidal sinus opacification is rare in isolated medial wall fractures. Prolapsed orbital fat can occur with medial wall fractures alone but is much more common when the orbital floor is involved.

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Treatment

Decisions regarding treatment in isolated medial wall fractures can be challenging, as they remain controversial in part because the relative rarity of isolated medial wall fractures leads to a lack of a good evidence basis for a therapeutic choice.

Conservative treatment. Some isolated medial wall fractures may be observed with long-term resolution of symptoms. Several studies have advocated conservative therapy even with prolapse of the medial rectus into the ethmoidal sinus. Those patients presenting with diplopia and exotropia do not necessarily have an entrapped medial rectus, even if it is displaced into the ethmoidal sinus. Those with negative forced ductions, diplopia and CT-proven medial rectus displacement can be observed for at least one month, given the increasing case reports of spontaneous recovery by this time.4 These patients may also be treated with oral nonsteroidal anti-inflammatory agents in an attempt to resolve edema and accelerate resolution of the diplopia. Even with resolution of exotropia and diplopia, CT scans may show persistent prolapse of the medial rectus into the ethmoidal sinus.4

Patients should be monitored closely during this period of observation. Worsening of diplopia or further restriction of extraocular movements, as well as the development of enophthalmos, may be indications for prompt surgery.

Surgical treatment. If forced ductions prove that there is true medial rectus entrapment, surgery is often indicated. Most surgical intervention is performed within two weeks after injury in order to allow time for reduction of swelling but prior to the onset of fibrosis. The goal of early surgery is to resolve diplopia or enophthalmos or to prevent the development of these symptoms. Although many cases are not straightforward, several clear indications for surgery exist. First, patients with diplopia, medial rectus entrapment on CT scan and positive forced ductions should be considered surgical candidates, especially if no improvement is seen in the first one or two weeks. These patients are less apt to resolve spontaneously than those with muscles that are merely prolapsed into the ethmoidal sinus. Second, patients with early onset enophthalmos of 3 mm or more should undergo surgery. Third, a trapdoor fracture, a linear fracture in which the injured bones return to their original position appearing normal on imaging but entrapping the surrounding soft tissues, including extraocular muscles, is an indication for surgery. And finally, patients with large medial wall fractures should be considered for surgery, as they are likely to have late enophthalmos.

Several surgical approaches have been used. The traditional frontoethmoidal and medial canthal methods appear to provide adequate access and visualization for repair. More recently, endoscopic endonasal approaches have gained popularity. Most repairs involve repositing the prolapsed soft tissue into the orbit, reconstructing the broken fragments and then possibly reinforcing the medial wall with alloplastic material (nylon foil, Marlex mesh, Silastic, Prolene, Vicryl mesh, titanium mesh) or bone grafts. The alloplastic implant may be left to rest on stable bones without fixation or anchored to adjacent bone with sutures, screws (including bioabsorbable screws), self-drilling screws or fibrin glue. Care must be taken to identify and avoid injury to the medial canthal tendon, lacrimal sac, trochlea and ethmoidal vessels and nerves. Postoperatively, complications may include persistent diplopia, limitation of gaze, proptosis or implant migration.

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Outcomes

The treatment goals for medial wall fractures include orthophoria, resolution of diplopia, full extraocular motility and avoidance of severe enophthalmos. Neither the ideal time period to observe nor the exact time to operate has definitively been shown. Yet, regardless of the physician’s approach most patients have successful outcomes and good cosmetic results.
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1 Nolasco, F. P. and R. H. Mathog. Otolaryngol Head Neck Surg 1995;112:549–556.
2 Burm, J. S. et al. Plast Reconstr Surg 1999;103:1839–1849.
3 Tse, R. et al. Plast Reconstr Surg 2007;119:277–286.
4 Yenice, O. et al. Ophthalmic Surg Lasers Imaging 2006;37:497–501.
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Dr. Rosenberg is a first-year resident and Dr. Glavas is an assistant clinical professor of ophthalmology. Both are at NYU Medical Center and the Manhattan Eye, Ear and Throat Hospital.

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