Orbital Medial Wall Fractures
Orbital Medial Wall Fractures
Fractures of the medial orbital wall result from blunt trauma to the periorbital area. The condition can result from traffic accidents, sports activities, violence or fall injuries. Medial wall fractures can occur alone or as part of a complex fracture. Medial wall fractures are commonly associated with orbital floor fractures. In addition, there may also be associated frontal, nasoethmoidal and maxillary fractures.
People with injuries to periorbital area may suffer from orbital fracture. Males outnumber females. High risk activities, such as contact sports.
Medial wall fractures are usually caused by injury at mid face. In comminuted fractures, the most common type, bone fragments and intraorbital contents (e.g.extraocular muscle, fat or soft tissue) may herniate into the ethmoidal sinus. Others types of fractures include the hinge fracture and the trapdoor fracture. Medial orbital wall blow out fractures, by definition is a pure internal fracture confining to orbital wall, without involvement of orbital rim. Two theories have been proposed to explain such phenomenon, hydraulic mechanism and buckling mechanism.
Hydraulic hypothesis states that the orbital floor or medial orbital wall are fractured when there is an increase in orbital pressure by a striking object which is larger than 5cm in diameter. The lateral wall and roof are usually thick enough to withstand such a trauma.
Buckling theory states that force exerting to orbital rim causes transient deformation and it is transmitted to the orbital floor or medial wall causing fracture.
The medial orbit is the thinnest of the orbital walls and is thus rendered more susceptible to fracture.
Avoiding trauma to face or periorbital area, e.g. wearing protective goggles in contact sports and preventing slip and fall injuries, may lower the risk of medial orbital wall fracture.
Recent trauma to face, nose or eye. The patient may report an increase in periorbital swelling after nose-blowing, which indicates communication between nasal cavity and orbit causing surgical emphysema around the eye. Some patients presenting with delayed enophthalmos warrant further assessment for an old or cicatricial process. Patients with a past incident of trauma may not recall any previous history of an injury.
In cases with medial rectus muscle or associated soft tissue entrapment, patients may complain of diplopia in horizontal gaze. There may be pain on eye movement. Children and young adults, may experience nausea, vomiting, bradycardia, dizziness because of the oculocardiac reflex. Sometimes, even without muscle entrapment, diplopia or limitation in extraocular movement is present due to soft tissue swelling within orbit.
Other symptoms include epistaxis (due to avulsion of anterior ethmoidal artery) or central spinal fluid rhinorrhea if there is concomitant nasal or orbital roof fracture respectively.
Complete eye examination is essential in all trauma cases, including measurement of visual acuity, intraocular pressure, relative afferent pupillary defect, red color desaturation, and dilated fundus examination.
On palpation, there is crepitus which indicates surgical emphysema around the eye. If there is concomitant orbital floor fracture, patient may have cheek numbness or orbital rim stepping.
Patients can have impaired horizontal eye movement in both adduction and abduction and they may complain of diplopia in such gazes.
Enophthalmos can be measured with exophthalmometer. In the early stage, enophthalmos may be masked due to soft tissue swelling. Repeat exophthalmometry in subsequent follow-up examinations may be appropriate to reveal the presence of enophthalmos. Sometimes there is proptosis, however, because of severe periorbital tissue edema. Although not common, retrobulbar hemorrhage can occur and presents with painful proptosis, raised intraocular pressure and a decrease in vision due to optic nerve compression. In such cases, urgent intervention may potentially be sight saving.
Besides the orbit, the trauma may cause periocular soft tissue injuries, such as eyelid laceration. Potential ophthalmic injuries, include globe rupture (corneal or sclera laceration), iridodialysis, lens instability, traumatic cataract, vitreous hemorrhage, commotio retinae, retinal hemorrhage or detachment, choroidal rupture and traumatic optic neuropathy.
Apart from ophthalmic examinations, one has to assess for any signs of the oculocardiac reflex including bradycardia, nausea, vomiting, syncope or even heartblock, which may happen when there is extraocular muscle entrapment, especially in children or young adults.
We should suspect patients having orbital fracture if there is history of trauma to periorbital area or face. Additional signs including horizontal ocular dysmotility, surgical emphysema and enophthalmos may hit us the presence of medial orbital wall fracture. Radiological investigation can confirm the diagnosis.
Computer tomography (CT) is the primary diagnostic tool in evaluating for orbital fractures, muscle entrapment or retrobublar hemorrhage. In addition, CT can help in assessing the size of fracture and plan subsequent surgical repair. While plain film x-rays of the orbit may reveal an ethmoidal sinus opacity, the test is insensitive way to pick up medial wall fracture.
Periorbital ecchymosis without fracture, in which there may be limitation in extraocular movement, not limiting to horizontal gaze.
When there is a medial wall fracture, patients should avoid nose-blowing to prevent the development of orbital emphysema and non-sterile tissue in sinuses getting into orbital cavity. Antibiotics should be given.
This is one of the controversies in the management of orbital fractures. A literature review from 1983 to 2002 and published the clinical recommendation of repair of orbital floor fracture in 2002 based on 31 reviewed articles (Burnstine MA, Ophthalmology 2002). The guideline can be adopted in medial wall fracture as well.
It is recommended to repair the fracture immediately if there is non-resolving oculocardiac reflex, marked extraocular motility, entrapment of extraocular muscle evidenced in CT or early enophthalmos.
Surgical repair should be performed within 2-week time when there is symptomatic diplopia and positive force duction test or large fracture causing latent enophthalmos. Repair is done within 2 weeks of initial trauma because fibrosis and scarring make delay repair difficult.
When there is good extraocular motility, minimal diplopia and no significant enophthalmos (i.e. <2mm and cosmetically acceptable), conservative management is adequate.
Last but not least, we also need to take into account patients’ age, pre-morbid condition and preference as operation is not without risks.
Fracture can be repaired either by open or endoscopic approach. In the open approach, accessing the inferior aspect of the medial wall is performed by a subciliary incision or transconjunctival incision. The approach can also be used for combined medial and inferior orbital wall fractures. For isolated medial wall fracture, a transcaruncular incision is an option.
In the endoscopic approach, the uncinate process is cut and ethmoidectomy is performed to delineate the fracture site at medial orbital wall. Herniated orbital tissue is reduced and an implant such as silastic, merocel or medpor tailored slightly larger than the defect is inserted. Forced duction testing and pulse test (in which globe is gently pushed externally and pulsation is observed through endoscope) are performed to confirm full ocular motility and proper placement of the implant. Post-operative nasal packing is necessary.
Comparison between open and endoscopic approaches is listed in Table 1:
|Fracture type/site||Can be use in different types of fractures||Best to use in medial wall fracture and trap door fracture|
|Limitations||Relatively limited posterior orbit visibility||Can’t be utilized in large defect|
|Complications||Lid malposition|| -Maxillary sinusitis (due to impaired sinus drainage)|
-Post op infraorbital paraesthesia (resolve 2-8 wks afterwards)
-Inadvertent displacement of bone fragment to orbital cavity
|Advantages||Slight advantageous with respect to the operation time, the length of hospital stay, and cost.|| -Can be used in early repairs|
-Less globe retraction
Fracture repair can potentially cause a drop in vision or even blindness if the optic nerve is injured during operation or if there is retrobulbar hemorrhage/hematoma that causes optic nerve compression and raised intraocular pressure. Persistent or worsening diplopia, implant related complications such as infection or migration of implant, absorption of bone graft may occur after operation. Lid malposition such as cicatrical ectropion is a known complication with subciliary incision and is reported to be less common in transconjunctival approach. However, some suggest careful tissue dissection can render similar rate of ectropion between the 2 methods.
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