BASICS

DESCRIPTION

• Greenstick fracture of the orbital floor or medial orbital wall resulting in ischemic entrapment of an extraocular muscle.

• Typically seen in the pediatric population, although young adults in their early 20s may be affected.

• Minimal external signs of trauma (lack of swelling, ecchymosis) mask the severity of the orbital injury, ergo the term “white-eyed blowout fracture” (WEBOF).

• System: ophthalmic

• Synonyms: trapdoor orbital fracture

EPIDEMIOLOGY

• Occurs in children and young adults

• No racial predilection

• No gender predilection is reported. However, in general males are more often involved in trauma

• The orbital floor is more commonly involved than the medial orbital wall (lamina papyracea).

• The etiology is typically due to a blunt force sports- related injury, motor vehicle accident, or physical altercation.

• Incidence and prevalence are unknown

RISK FACTORS

• Pediatric age group

• Recent trauma

GENERAL PREVENTION

• Avoidance of eye trauma

• WEBOF in children is most commonly due to sports injury, but it may also occur from other mechanisms (motor vehicle accident, altercation, etc.).

• The use of eye protection in the form of polycarbonate safety glasses, goggles, or eye shields is advised in all children involved in sports.

• The use of appropriate restraining devices is advised in all children in motor vehicles.

PATHOPHYSIOLOGY

• A blowout fracture of the orbital bones is postulated to occur through two mechanisms:

– A blow to the globe and orbit momentarily increases intraorbital pressure, causing the thin bones of the orbital floor and/or medial wall to “blowout” into the adjacent paranasal sinus.

– A blow to the inferior orbital rim causes the orbital floor to buckle and break into the maxillary sinus.

• The bones of children have not fully calcified and in general are more pliable than those of adults.

– When a child sustains a blow to the periocular region, the thin bone of the orbital floor or medial orbital wall cracks and momentarily opens into the adjacent sinus. The increased intraorbital pressure causes orbital fat and the adjacent extraocular muscle to herniate into the fracture.

– In adults, the fractured bone usually remains in place within the sinus. Because of the pliability of pediatric bones, the fractured orbital bone immediately snaps back into position, much like a trapdoor on a hinged spring.

– This results in tight incarceration of the orbital soft tissue (fat and muscle), leading to ischemic contracture (Volkmann’s contracture) of the extraocular muscle.

– The entrapped muscle limits ocular movement with resultant diplopia (double vision). On attempted ocular movement, the child experiences an oculocardiac reflex (Aschner phenomenon), a vagal response stimulated by a connection between the trigeminal and vagus nerves.

– The oculocardiac reflex manifests as nausea, vomiting, and sometimes fainting, mimicking symptoms of concussion. This can be the cause of bradycardia and heart block.

ETIOLOGY

As described above

COMMONLY ASSOCIATED CONDITIONS

• Intraocular injury (including hyphema, vitreous hemorrhage, and choroidal rupture)

• Oculocardiac reflex, bradycardia, heart block

• Concussion and intracranial injury, including hemorrhage, are uncommon associations in the vast majority of WEBOFs.

DIAGNOSIS

HISTORY

• Blunt trauma to the periocular region.

• Diplopia.

• Pain of attempted eye movement.

• Nausea and vomiting, especially with attempted eye movements.

• Loss of consciousness is NOT a typical feature of WEBOF.

PHYSICAL EXAM

• External examination with minimal signs of injury: minimal eyelid edema or ecchymosis, subconjunctival hemorrhage

• Severe restriction in upgaze (with orbital floor fractures) or in abduction (with medial wall fractures). The child often refuses to open the eye because of discomfort.

• Cheek numbness from infraorbital nerve contusion

• Signs and symptoms can often be confused for a concussion if the eye is not examined.

DIAGNOSTIC TESTS & INTERPRETATION

Lab

Drug and alcohol screening as indicated for preoperative clearance for general anesthesia

Imaging

Initial approach

• CT of the orbits with axial and coronal images. Coronal images are crucial for diagnosis. Sagittal images are optional.

• Both bone and soft tissue windows should be examined. WEBOFs are notoriously easy to miss on imaging without a high degree of suspicion because often the trapdoor fracture snaps back into an almost normal or normal position.

• If there is a suspicion of intracranial injury, head CT should be obtained.

• A head CT is NOT equivalent to orbital CT and will not afford adequate views of the orbital bones.

• Use of age- and weight-adjusted CT radiation doses in children to minimize radiation exposure.

• Avoid plain films.

• Avoid MRI because of poor bony detail.

Follow-up & special considerations

No additional imaging is needed postoperatively unless there is a question about the effectiveness of the surgical repair or positioning of the orbital implant.

Diagnostic Procedures/Other

If bradycardia and oculocardiac reflex are severe and persistent, cardiac monitoring may be necessary in a minority of cases. If indicated, the patient should be admitted to the pediatrics service.

Pathological Findings

• Incarceration and ischemia of the inferior (or less commonly medial) rectus muscles within a trapdoor fracture

• Alternatively, the perimuscular fascia and orbital fat may be caught within the fracture.

DIFFERENTIAL DIAGNOSIS

• Intracranial injury or concussion

• Contusion injury to the extraocular muscle. In many cases of orbital fracture, soft tissue contusion and edema manifest clinically as diplopia and external ophthalmoplegia. However, such cases typically lack a significant oculocardiac reflex and patients do not complain of severe nausea and vomiting.

TREATMENT

MEDICATION

• WEBOF requires urgent surgical exploration (within 72 h) in essentially all cases

• Medical therapy is a secondary issue

• Some clinicians will prescribe a 1-week course of postoperative systemic antibiotic therapy as prophylaxis against infection. There is no evidence that this is effective in an otherwise healthy patient.

• Some clinicians will prescribe a 1-week course of postoperative systemic corticosteroids to decrease posttraumatic inflammation and fibrosis in the hopes of decreasing the incidence of restrictive strabismus. There is no evidence that this is effective.

• Antiemetics may be prescribed for severe nausea and vomiting but may not be effective.

ADDITIONAL TREATMENT

General Measures

• The patient is made NPO and cleared for general anesthesia.

• Because of the possibility of intraoperative paranasal sinus bleeding into the nasopharynx, laryngeal mask anesthesia should be avoided. Instead, endotracheal intubation for more complete airway protection is recommended for all orbital fracture repairs.

• The risks of surgery, including visual loss, infraorbital hypesthesia, and persistent diplopia, which could require additional surgery or prisms, are discussed in detail with the patient and parents. The option of conservative observation should be offered with caution, since this may result in severe extraocular muscle fibrosis.

• The patient and parents should be aware that in the immediate postoperative period, the diplopia may worsen. Nausea and vomiting resolve almost immediately. Diplopia and extraocular motility typically take weeks to months to improve or resolve.

Issues for Referral

Urgent referral to the appropriate orbital specialist is indicated in all patients with WEBOF to optimize timing of surgical repair and minimize the possibility of posttraumatic strabismus and diplopia.

SURGERY/OTHER PROCEDURES

• Surgical exploration with release of the entrapped tissue

• Repair of the trapdoor fracture. If adequate realignment of the fracture occurs with no evidence of soft tissue herniation, an orbital implant may not be needed.

• In most cases, an orbital wall defect is present after soft tissue release, potentially allowing for recurrent soft tissue entrapment. An orbital implant (usually an absorbable or nonabsorbable alloplastic sheet, based on surgeon preference) is placed to bridge the defect.

• Most WEBOF repair can be performed transconjunctival without a lateral canthotomy/cantholysis.

IN-PATIENT CONSIDERATIONS

Initial Stabilization

• Full ophthalmic examination to rule out intraocular and optic nerve injury

• Orbital imaging

• Cardiac monitoring as indicated

Admission Criteria

• Intractable nausea and vomiting

• Bradycardia or heart block

IV Fluids

• In many cases, patients with WEBOF have severe nausea and vomiting from the oculocardiac reflex.

• Some patients present without oral intake since the initial trauma, which may have occurred several days prior.

• Because of the possibility of dehydration, patients should be rehydrated preoperatively as indicated with the assistance of a pediatrician or anesthesiologist.

Nursing

• Following fracture repair, most patients with WEBOF experience immediate relief of their nausea and vomiting, and oral intake normalizes quickly. Antiemetics are typically not needed following successful repair.

• There is a risk of orbital hemorrhage with potential compressive optic neuropathy in any patient undergoing orbital surgery. Visual and pupillary function should be monitored over the first 12 hours postoperatively. If the nursing staff is unfamiliar with examination techniques, then the physician should assume these responsibilities.

• Any excessive swelling, pain, or bleeding should be reported to the physician immediately.

• Frequent iced or cold compresses are essential during the first 12 hours following fracture repair to decrease postoperative edema and pain. Many clinicians recommend compresses 20 minutes on and 20 minutes off while the patient is awake.

• Oral or intermuscular narcotics for pain management. This is usually unnecessary following most WEBOF repair.

• Diplopia often persists for days, weeks, or months following WEBOF repair and is not an indication of a postoperative complication.

• Antibiotic ophthalmic ointment to the conjunctival incision site

Discharge Criteria

• Resolution of nausea and vomiting. Vasovagal complaints resolve almost immediately. If they persist for more than 24 h postoperatively, then reexploration may be necessary to rule out inade-quate initial release or postoperative reentrapment.

• Resolution or marked decrease in pain with eye movement

• No evidence of postoperative hemorrhage or optic neuropathy

• Diplopia will be present postoperatively in a significant proportion of patients, and it is not an indication to delay discharge.

• Most patients can be discharged home within 24 h of WEBOF repair.

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

• Depending on surgeon preference, the surgery can be performed on an outpatient or inpatient basis.

• Patients are usually seen within 1 week following repair.

• Ophthalmic ointment is typically discontinued 1–2 weeks following repair.

• Systemic antibiotics and corticosteroids, if prescribed, are usually discontinued within the first 2 weeks following repair.

• Iced or cold compresses are continued for the first 2–3 days following repair.

• The patient and his or her family are instructed to avoid any nose blowing, heavy lifting, exercise, or sports activities for 2 weeks following repair. Air travel is avoided for 1–2 weeks following repair. If essential, then the patient is instructed to use intranasal decongestants before take-off and landing to help equalize paranasal sinus pressure.

• The patient is given detailed instruction for monitoring of visual function and symptoms of orbital hemorrhage.

• An emergency telephone number is clearly included in the instruction sheet in case of visual problems or signs suggestive of orbital hemorrhage.

• The use of aspirin and related products may resume as needed 2 weeks after repair but should be avoided in the early postoperative period to reduce the potential for orbital hemorrhage.

• If diplopia persists postoperatively, the patient can occlude one eye with either a “pirate patch” or with adhesive tape over one lens of their glasses. Occlusion amblyopia is not a concern in patients older than 6 years. In children younger than 4 years, care must be taken to avoid prolonged occlusion of one eye; in this age group, alternating occlusion of each eye on a daily basis is recommended.

• A dilated fundus exam should be repeated at 6–12 weeks to assure that there are no late peripheral retinal abnormalities.

Patient Monitoring

• As already mentioned, postoperative diplopia and limited motility of the affected extraocular muscle is common after successful WEBOF repair. The patient and his or her family should be counseled about this probability preoperatively.

• No attempt at strabismus surgery should be made for at least 6 months following WEBOF repair. In most cases, if timely fracture repair was performed initially, extraocular motility will improve markedly over the ensuing weeks to months and in many cases, diplopia will resolve completely.

• After the initial postoperative follow-up visit, the patient is instructed to return 3–4 weeks later. If the diplopia has resolved, no additional therapy is indicated. If diplopia is still present, then initial strabismus pattern measurements are made utilizing prism bars and the patient is rechecked at regular intervals over the ensuing 6–9 months.

DIET

Regular, without restrictions

PROGNOSIS

• If repaired in a timely fashion, the prognosis for WEBOF is excellent, with most patients experiencing complete resolution of diplopia in useful gaze positions. Diplopia in extremes of gaze (typically upgaze) is usually left untreated.

• Clinical studies have shown that a significant delay in surgical repair (>2 weeks) results in a higher incidence of posttraumatic diplopia, which may not be amenable to further correction—thus the mantra of urgent surgical repair of WEBOF.

• Since there is a possibility of persistent diplopia from WEBOF even with timely repair, it behooves the surgeon to minimize excessive delay in surgical intervention. Most experts agree that repair within 72 h of injury is reasonable.

COMPLICATIONS

• Initial misdiagnosis as concussion or “normal” orbital CT, which may delay definitive treatment

• Persistent diplopia

• Optic neuropathy from intraoperative injury or postoperative orbital hemorrhage

• Persistent infraorbital dysesthesia (hypesthesia or neuralgia)

• Enophthalmos or hypoglobus. Unlikely given the small size of the initial fracture

• Incisional scarring

• Lid retraction or other eyelid malposition

• Implant migration or extrusion

• Postoperative infection (including sinusitis and orbital cellulitis)

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