Opthalmology

Orbital Floor Blowout Fracture

CASE

A 16-year-old male presents with head trauma. The patient was in gym class when another classmate ran into him, kneeing him in the left eye. There was no loss of consciousness. On presentation, the patient complains of headache, dizziness, nausea, visual disturbance, and photophobia. He has vomited several times. On review of systems, the patient also endorses double vision and numbness over the left cheek. The patient’s mother notes he is alert but is slow to respond to questions.  He has no prior history of facial fractures.

Physical Exam

BP 130/70, HR 58, RR 20, SpO2 99% on RA, Temp 98.6 F

The patient is alert and oriented.  He appears uncomfortable but is in no acute distress.

HEENT exam with left periorbital ecchymosis and edema, with tenderness to palpation. Diminished sensation to light touch over cheek and upper lip. Nasal bridge swelling and tenderness, with subtle nasal deviation to the right. No septal hematoma. Symmetric smile.

Pupils are equal, round, and reactive to light. No hyphema or subconjunctival hemorrhage. Left eye with decreased up-gaze as compared to the right. Extraocular movements of the left eye are painful.

The neck has normal range of motion. There is no cervical midline tenderness to palpation.

The patient’s history and examination are significant for trauma to the left eye and face. His examination reveals bony tenderness, with decreased sensation to light touch, and evidence of inferior rectus entrapment as evidenced by abnormal extraocular movements. These findings are concerning for orbital blow-out fracture. There is also concern for nasal bone fracture given nasal bridge swelling, tenderness, subtle deviation, and epistaxis. Given patient’s nausea, vomiting, dizziness, and slowed responses to questions (as per patient’s mother), intracranial injury was also considered.

The patient underwent a CT of the brain and face, with thin (1mm) cuts through the orbits (Figure 1).

Figure 1: Axial CT of the face (bone window) with fracture through the left orbital floor, with herniation of the orbital fat (“teardrop” sign) and inferiorly displaced inferior rectus muscle

Figure 1: Axial CT of the face (bone window) with fracture through the left orbital floor, with herniation of the orbital fat (“teardrop” sign) and inferiorly displaced inferior rectus muscle

DISCUSSION

Figure 2: Anatomy of the orbit (https://en.wikipedia.org/wiki/File:Orbital_bones.png)

Figure 2: Anatomy of the orbit (https://en.wikipedia.org/wiki/File:Orbital_bones.png)

The orbit is composed of six bones. The frontal bone forms the superior orbital rim and the roof of the orbit. The sphenoid bone and the zygomatic bone form the lateral wall of the orbit. The maxilla and the zygomatic bone form the infraorbital rim and floor of the orbit. Finally, the maxilla and ethmoid bones form the medial wall of the orbit (Figure 2).

Housed within, or within in close proximity to the bony orbit are the globe, six extra-ocular muscles, the infraorbital and supraorbital nerves, lacrimal duct system, medial and lateral canthal ligaments, and 4 pairs of sinuses (Neuman).

A blowout fracture is a fracture through any of the orbital walls, with an inferior fracture through the floor being the most common (Knipe). It is caused by direct force to the orbit. In children, nearly 50% of these injuries occur during sports, with the direct blow usually coming from a ball or another player (Hatton).

A trap door fracture is a sub-type of the orbital floor fracture. It is a linear fracture that inferiorly displaces and then recoils back to near-anatomic position. With this movement there is concern for entrapment of orbital fat and inferior rectus muscle, resulting in ischemia, restriction of ocular movement, and visual disturbance (Hacking). The trap door fracture is predominantly seen in the pediatric population, owing to increased elasticity of the orbital floor (Chung, Grant).

Clinically, a patient will present with periorbital edema and ecchymosis. Altered sensation or numbness over the cheek, upper lip, and upper gingiva is suggestive of infraorbital nerve injury. Proptosis of the eye is suggestive of orbital hematoma. A posteriorly displaced globe (enophthalmos) is suggestive of increased orbital volume secondary to fracture. An inferiorly displaced globe (orbital dystopia) is a result of muscle and fat prolapse into the maxillary sinus. Restricted and/or painful extraocular movements are suggestive of muscle entrapment (Neuman).

In children, a phenomenon called the oculocardiac reflex can occur. Stimulation of the ophthalmic division of the trigeminal nerve due to traction or pressure on the extraocular muscles or globe results in excitation of the vagus nerve, leading to bradycardia, nausea, and syncope. In severe cases, asystole can occur (Sires).

CT of the face, with thin (1mm) cuts through the orbit is the primary modality used for identification of orbital blowout fractures. Plain radiographs of the face and orbits are no longer the gold standard as they have poor sensitivity and specificity.  Trap door fractures may be occult, but any evidence of soft tissue herniation into the maxillary sinus (also known as the “teardrop” sign) should raise suspicion for a clinically significant fracture.

These injuries can be severe, and are often more significant in the pediatric population than the adult population, owing to associated soft tissue and muscular injuries. Almost half of children with this injury will require surgery, most frequently due to entrapment. Nearly half of pediatric patients will have ocular injuries (globe rupture, hyphema, retinal tear) and nearly one third of patients will have a second facial fracture (Hatton). 

Urgent ophthalmology and facial surgery consultations are indicated for orbital floor fractures with concern for entrapment (Chung).

Symptomatic treatment includes:

  • Head of bed elevation

  • Ice

  • Sinus precautions: no nose blowing, sneeze with the mouth open, no straw use or sniffing

  • Analgesia and anti-emetics as needed

 

For orbital fractures with extension into a sinus, the use of prophylactic antibiotics has limited data and often varies by institution (Neuman).

Corticosteroids are recommended for patients with diminished extraocular movements to reduce swelling and expedite improvement in diplopia (Neuman).

For orbital blowout fractures with evidence of entrapment and/or oculocardiac reflex, repair should be performed within 24-48 hours. Delayed repair (more than 2 weeks after injury) can be considered if mild-moderate diplopia is not spontaneously improving, or patient has worsening of enopthalmos > 2mm after initial edema and inflammation has resolved.  Other indications for surgical repair include large fracture (involvement of greater than 50% of the orbital floor) or multiple fractures (Chung).

 

CASE CONCLUSION

The patient was admitted for observation overnight in the setting of persistent nausea, vomiting, borderline bradycardia, and diplopia. He was placed on oral prednisone, as well as anti-inflammatory medication. Overnight his symptoms and heart rate improved, although he had persistent diplopia, with diminished upward gaze of the left eye. He was discharged home on hospital day 1, with plan for ophthalmology and facial surgery follow-up for operative planning.

Faculty Reviewer: Dr. Jane Preotle

 

REFERENCES & FURTHER READING

  1. Chung, Stella Y., and Paul D. Langer. “Pediatric Orbital Blowout Fractures.” Current Opinion in Ophthalmology, vol. 28, no. 5, 2017, pp. 470–476., doi:10.1097/icu.0000000000000407.

  2. Grant, John H., et al. “Trapdoor Fracture of the Orbit in a Pediatric Population.” Plastic and Reconstructive Surgery, vol. 109, no. 2, 2002, pp. 490–495., doi:10.1097/00006534-200202000-00012.

  3. Hacking, Craig. “Trapdoor Fracture.” Radiopaedia.org, radiopaedia.org/articles/trapdoor-fracture.

  4.  Hatton, Mark P., et al. “Orbital Fractures in Children.” Ophthalmic Plastic and Reconstructive Surgery, vol. 17, no. 3, 2001, pp. 174–179., doi:10.1097/00002341-200105000-00005. 

  5. Knipe, Henry, and Frank Gaillard.  “Orbital Blowout Fracture.” Radiopaedia.org, radiopaedia.org/articles/orbital-blowout-fracture-1.

  6. Neuman, Mark, and Richard G Bachur. “Orbital Fractures.” UpToDate, www.uptodate.com/contents/orbital-fractures.

  7. Sires, Bryan S. “Orbital Trapdoor Fracture and Oculocardiac Reflex.” Ophthalmic Plastic & Reconstructive Surgery, vol. 15, no. 4, 1999, p. 301., doi:10.1097/00002341-199907000-00014.

  8. Soll, D. B., and B. J. Poley. “Trapdoor Variety of Blowout Fracture of the Orbital Floor.” Plastic and Reconstructive Surgery, vol. 36, no. 6, 1965, p. 637., doi:10.1097/00006534-196512000-00017. 

AEM Early Access 22: Test Characteristics of Point of Care Ultrasound for the Diagnosis of Retinal Detachment in the Emergency Department

Welcome to the twenty-second episode of AEM Early Access, a FOAMed podcast collaboration between the Academic Emergency Medicine Journal and Brown Emergency Medicine. Each month, we'll give you digital open access to an recent AEM Article or Article in Press, with an author interview podcast and suggested supportive educational materials for EM learners.

Find this podcast series on iTunes here.

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DISCUSSING (CLICK ON LINK FOR FULL TEXT, OPEN ACCESS THROUGH January 31):

Test Characteristics of Point of Care Ultrasound for the Diagnosis of Retinal Detachment in the Emergency Department. Daniel J. Kim, MD,  Mario Francispragasam, MEd, MD, Gavin Docherty, MD, Byron Silver, MSc, MD, Ross Prager, BSc, Donna Lee, MD, RDMS, and David Maberley, MSc, MD. 

LISTEN NOW: FIRST AUTHOR INTERVIEW WITH Daniel J. Kim, MD

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Daniel J. Kim, MD

Department of Emergency Medicine

Vancouver General Hospital

Director, Ultrasound Fellowship Program

University of British Columbia

@dan___kim

ABSTRACT

Previous studies of point of care ultrasound (POCUS) have reported high sensitivities and specificities for retinal detachment (RD). Our primary objective was to assess the test characteristics of POCUS performed by a large heterogeneous group of emergency physicians (EPs) for the diagnosis of RD.

Methods: This was a prospective diagnostic test assessment of POCUS performed by EPs with varying ultrasound experience on a convenience sample of emergency department (ED) patients presenting with flashes or floaters in one or both eyes. After standard ED assessment, EPs performed an ocular POCUS scan targeted to detect the presence or absence of RD. After completing their ED visit, all patients were assessed by a retina specialist who was blinded to the results of the POCUS scan. We calculated sensitivity and specificity with associated exact binomial confidence intervals (CI) using the retina specialist's final diagnosis as the reference standard.

Results: A total of 30 EPs enrolled 115 patients, with median age of 60 years and 64% female. The retina specialist diagnosed RD in 16 (14%) cases. The sensitivity and specificity of POCUS for detecting RD was 75% (95% CI 48%-93%) and 94% (95% CI 87%-98%), respectively. The positive likelihood ratio was 12.4 (95% CI 5.4-28.3), and negative likelihood ratio was 0.27 (95% CI 0.11-0.62).

Conclusions: A large heterogeneous group of EPs can perform POCUS with high specificity but only intermediate sensitivity for RD. A negative POCUS scan in the ED performed by a heterogeneous group of providers after a one-hour POCUS didactic is not sufficiently sensitive to rule out RD in a patient with new onset flashes or floaters. This article is protected by copyright. All rights reserved.

ADDITIONAL RELATED READING

Vrablik et al, 2015. The diagnostic accuracy of bedside ocular ultrasonography for the diagnosis of retinal detachment: a systematic review and meta-analysis. https://www.ncbi.nlm.nih.gov/pubmed/24680547

Jacobsen et al, 2016. Retrospective Review of Ocular Point-of-Care Ultrasound for Detection of Retinal Detachment: https://www.ncbi.nlm.nih.gov/pubmed/26973752

Baker et al, 2017. Can emergency physicians accurately distinguish retinal detachment from posterior vitreous detachment with point-of-care ocular ultrasound?: https://www.ncbi.nlm.nih.gov/pubmed/29042095

AEM Commentary on this paper: https://www.ncbi.nlm.nih.gov/pubmed/30112843

Other commentaries on this paper:

NEJM Journal Watch: https://www.jwatch.org/na46896/2018/06/11/dont-try-rule-out-retinal-detachment-with-poc-ultrasound

UC San Diego Ultrasound Division: http://emultrasound.sdsc.edu/index.php/2018/07/25/retinal-detachment/

How Do You Use a Schiotz Tonometer?

Video by Scott Pasichow; Text by Joseph Moran

Case intro:

A 40-year-old patient with a history of migraine and glaucoma presented to the ED with concern of acute frontal headache with visual changes. The patient was well-appearing without acutely concerning neurologic or ophthalmologic findings on physical exam. As part of his workup, an intraocular pressure was desired to rule out increased IOP/glaucoma. An electronic tonometer was unavailable for use. Instead, the Schiotz tonometer was utilized. 

A Schiotz tonometer is an analog, weight-based tool to assess intraocular pressure. It uses a weight on a flat transducer which is opposed by the intraocular pressure. The IOP is transferred through the weighted tonometer arm and gives a reading on a needle, which is then used on a conversion table to calculate IOP.

Case contents:

Tonometer, 7.5, 10, and 15 gram weights, conversion table.

Steps of use:

  1. Anesthetize eye

  2. Apply one of the 3 included weights to the Schiotz tonometer as demonstrated in the video. Start at 5.5 and change to heavier as needed if reading is too high (e.g., off the charts)

  3. Have the patient look straight ahead while lying supine

  4. Apply the flat round bottom of the tonometer to the middle of the cornea (e.g., mid-pupil)

  5. Write down (or remember) the reading on the needle

  6. Use conversion table based on weight used and needle reading to calculate IOP

  7. Clean with alcohol swab

Case conclusion:

The patient's IOP was within normal limits, symptoms improved with symptomatic care, and the patient was discharged home with outpatient follow up and return precautions.

Faculty Reviewer: Dr. Whit Fisher