White-Eyed Blow Out Fracture

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 by Tal Rubinstein, MD on April 19, 2021.


Disease Entity

White-eyed blow out fracture (WEBOF) is a term for an orbital fracture with restrictive strabismus. ICD codes include fracture codes (e.g. S02.40, S02.32) and restricted motility/diplopia codes.

Disease

A WEBOF is a type of orbital fracture with tissue entrapped in small orbital break resulting in restrictive strabismus.

Etiology

As with other fractures, a WEBOF is due to trauma. The trauma can be a direct or glancing blow to the eye and/or periorbital tissue and commonly occurs during sporting activities. White-eyed blow out fracture (WEBOF) is a term coined by Jordan and colleagues describing the paucity of external findings with a small fracture and restrictive strabismus and diplopia and is most commonly seen in children and young adults [1].

Risk Factors

Pediatric age group and male gender are more prone to WEBOFs. The average age for a WEBOF is 10-12 years.

General Pathology

WEBOFs are usually caused by blunt force injury to the eye or orbital rim.

Pathophysiology

The theoretical pathophysiology is of a force applied to the eye/orbital rim transmitting forces to the orbit and an equatorial expansion of the intraorbital tissue. This expansion puts pressure on the orbital bones and can lead to a break in one of the weaker areas of bone, most commonly the orbital floor. Due to the less calcified, more flexible bone seen in the pediatric population, the bone can crack and open as if on a hinge. This trapdoor of bone can then snap back into position when the pressure on the orbital tissue has decreased and capture orbital tissue in the process. This incarcerated tissue can be fat and/or an extraocular muscle, generally the inferior rectus muscle.

Primary prevention

General safety guidelines to prevent trauma and activity specific sports eye wear are recommended.

Diagnosis

WEBOFs are generally diagnosed based on the history and clinical examination. Radiographic studies can overlook the small, non-displaced fracture.

History

These fractures occur in a younger age demographic in the setting of recent trauma. There may be a delay in presentation due to the lack of significant external findings (e.g. bruising) and even possibly a reportedly "normal" CT scan of the head and face.

Physical examination

On examination, patients often have an unremarkable external examination with a paucity of facial bruising and/or swelling as the name "white eyed" implies. Patients may preferentially be limiting eye opening and/or motility. With motility there is marked external ophthalmoplegia, most commonly vertically due to a preponderance of orbital floor involvement. This may be accompanied by nausea and vomiting, due to the oculocardiac reflex, and/or pain with motility. There may or may not be decreased sensation due to infraorbital nerve injury. Enophthalmos is uncommon and generally the remainder of the eye examination, including full dilated examination, is unremarkable.

Signs

The external signs can be absent or quite subtle, as the name suggests. There may be notable restriction in motility, generally vertically. Additionally, with attempted ductions the child may vomit and/or become bradycardic. Rarely asystole or cardiac arrythmia may also occur.

Symptoms

The child may have double vision on opening or moving the eyes, pain with eye movement, diplopia and nausea.

Clinical diagnosis

A WEBOF is generally a clinical diagnosis. A pediatric or young adult patient with restrictive strabismus with pain after trauma and minimal external signs is generally suspected of having a WEBOF even without further testing. If the patient is able to tolerate forced ductions that can confirm the clinical diagnosis, but is generally not needed or tolerated.

Diagnostic procedures

A CT scan of the orbits and sinuses is generally performed in addition to a full eye exam, despite WEBOF being a clinical diagnosis. The CT will generally demonstrate a linear orbital floor fracture parallel to the canal or be read as no fractures. The incarcerated soft tissue, fat +/- extraocular muscle (EOM), is seen in the adjacent sinus and may be reported as a sinus polyp. The portions of the incarcerated EOM within the orbit may be distorted or have areas where the muscle can not be identified, the "missing muscle sign".

Laboratory test

n/a

Differential diagnosis

As with any trauma, a full exam should be performed to rule-out other or additional diagnoses. Laceration of an EOM or paresis of a muscle could cause some of these signs. Patients are often initially diagnosed with a concussion prior to the WEBOF being identified.

Management

WEBOF should ideally have any entrapped tissue(s) surgically released within 24-48 hours of injury.

Medical therapy

Medical therapy should be used to control nausea and vomiting and cardiac monitoring if needed prior to surgical repair.

Surgery

Surgery is performed under general anesthesia and consideration for full endotracheal intubation given possible bleeding into the nasopharynx. Once the patient is asleep and draped, leaving both eyes in the surgical field, forced ductions can be performed at baseline. There are multiple approaches that can be used for repair, one is described here. For the most common WEBOF of the orbital floor, a transconjunctival approach can be used and lateral canthotomy is rarely needed though there are multiple approaches that can be used for repair.

After placement of a scleral shell and injection of the inferior cul-de-sac with local anesthetic containing epinephrine, a 4-0 silk suture is passed through the eyelid margin and the eyelid is everted on a Desmarres retractor. The conjunctiva is cauterized 1 mm below the inferior border of the tarsal plate with bipolar cautery and incised with scissors. A conjunctival/lower lid retractor flap is then elevated with Westcott scissors, through which an additional traction suture is placed. The dissection plane is carried preseptally toward the inferior orbital rim in a blunt fashion. Soft tissue overlying the inferior orbital rim is incised with Bovie cautery while protecting the globe and intraorbital contents with a coated malleable retractor. The periosteum is elevated around the arcus marginalis and orbital floor using a Freer elevator and malleable retractor in a hand-over-hand technique. Prolapsed and entrapped tissue is encountered a variable distance from the arcus marginalis. The surgeon should avoid the tendency of simply elevating soft tissue out of the maxillary sinus, which is a common and acceptable maneuver when repairing the wider orbital floor fractures seen in adults. In WEBOF, such traction on the entrapped tissue may cause further damage to the incarcerated muscle. Instead, the surgeon should gently push the hinged fracture into the maxillary sinus with the Freer elevator, effectively reopening the trapdoor and facilitating the elevation of prolapsed soft tissue back into the orbit, a “push and sweep” motion with the elevator. The fracture and trapped tissue are followed posteriorly into the orbit until all tissue is freed and reposited into the orbital space. The surgeon will often encounter an inferior rectus muscle which is edematous and dusky, consistent with direct contusion and ischemic injury. Forced ductions are again performed, but on occasion may still be positive even with complete release of entrapped soft tissue because of edema or early fibrosis, especially if there is a significant delay in surgical repair.

If the fractured bone realigns with little or no defect noted, as is common, some surgeons will opt against placement of any implant, while others will use absorbable materials, and still others will proceed with placement of a permanent alloplast such as porous polyethylene. Regardless of the alloplast, correct implant sizing and placement are critical to minimize iatrogenic entrapment and implant extrusion. In a properly sized and placed implant, there should be no soft tissue herniation around the implant and the anterior border of the implant should remain in the natural depression just behind the arcus marginalis. The position of the implant should be rechecked after forced ductions are performed. Any migration anterior to the arcus marginalis indicates incorrect positioning or an oversized implant. With proper sizing and placement, no additional implant fixation is needed. Some surgeons also prefer to minimize closure of soft tissues and avoid layered closure of eyelid tissue. The orbital septum should not be included in any closure. Some surgeons will close conjunctiva, but simply realigning the conjunctival edges followed by placement of a small amount of antibiotic ointment is also reasonable [2].

Surgical follow up

Postoperatively, the patient’s vision and pupillary reactivity are checked once the patient is awake to assure that there is no evidence of orbital compartment syndrome or optic neuropathy. Although there is an understandable trend toward outpatient orbital fracture repair in an ambulatory care setting, a so-called “23-hour admission” can be especially important in children, who may be uncooperative postoperatively and not allow for adequate postoperative assessment of vision at home by the parents. Any pre-operative nausea, vomiting, and pain with ductions should resolve almost immediately after surgery.

Complications

See orbital fracture for complications.

Prognosis

Diplopia may linger for weeks and may paradoxically worsen in the immediate postoperative phase. This is an important point to discuss with the patient and parents before surgery. It is not uncommon for the freed muscle to remain paretic for days to weeks, resulting in a marked hypertropia of the eye in the case of inferior wall WEBOF. As the inferior rectus heals and recovers function, the strabismus improves and hopefully resolves completely. On occasion, a small residual diplopia may persist in extreme up- or downgaze. If significant strabismus and diplopia is present several weeks after repair and an adequate reduction was performed intraoperatively, intramuscular fibrosis is likely present. Rarely, re-entrapment of the muscle may occur in the first week postoperatively, and typically follows an activity that resulted in a Valsalva maneuver in patients where no orbital floor implant was placed. Very young patients (<4 years old) with postoperative diplopia or strabismus should be followed for the development of amblyopia. Otherwise, serial strabismus measurements should be performed to document improvement or stability. Strabismus surgery, when necessary, should be delayed for at least six months following initial repair.

References

  1. Jordan DR, Allen LH, White J, Harvey J, Pashby R, Esmaeli B. Intervention within days for some orbital floor fractures: the white-eyed blowout. Ophthal Plast Reconstr Surg 1998;14:379-90
  2. Lane KA, Bilyk JR, Taub D, Pribitkin EA. "Sutureless" repair of orbital floor and rim fractures. Ophthalmology 2009;116:135-8 e2.
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