a b s t r a c t

Objective: The purpose of this study is to identify an accurate and reliable computed tomographic (CT) measure- ment that can identify those patients presenting to the emergency department (ED) with orbital floor fracture (BOF) who require Surgical repair to prevent ensuing visually debilitating diplopia and/or enophthalmos.

Methods: In this retrospective institutional review board-approved study, we reviewed 99 patients older than 18 years with orbital fractures treated in a level I trauma center from 2011 through 2015. Thirty-three patients met the inclusion criteria of having an isolated BOFs with or without a minimally displaced medial wall fracture. The maxillofacial CT of these patients, which included axial, coronal, and sagittal reconstruction of the face in both soft tissue and bone algorithm, were independently reviewed by a neuroradiologist and an oculoplastic surgeon. Each reviewer analyzed the images to answer the following 3 questions: (1) extent of the fracture fragment; greater than or less than 50%? (2) involvement of the inframedial strut (IMS)? and (3) cranial-caudal discrepan- cy of the orbits. This novel measurement was defined as the difference between the cranial-caudal dimension (CCD), measured just posterior to the globe, of the fractured orbit minus the CCD of the normal side. Electronic medical record was reviewed to determine the course of recovery, ophthalmologist assessment of the globe, mo- tility, diplopia, and the need for operative repair. Statistical analysis was performed to determine the accuracy of the measured CT parameters for the prediction of those who would ultimately require surgical repair.

Results: Of the 33 patients included in the study, 8 patients required surgical correction of their BOFs. Others were man- aged conservatively. The accuracy of BOF N 50% for predicting those requiring surgical repair was 48%. The accuracy of IMS involvement was 74%. Using a threshold CCD value of 0.8 cm, the accuracy of CCD was 94%. Cranial-caudal discrepancy had a sensitivity of 100% and specificity of 92%. ? Agreement between the 2 readers evaluating the CT images was 0.93.

Conclusion: Initial maxillofacial CT studies obtained in the ED for those with BOF is used to predict which patients may need urgent surgical repair. In this report, we introduce a new CT measurement, called CCD. Cranial-caudal discrepancy greater than 0.8 cm is predictive of the development of diplopia and/or enophthalmos that will require surgical correction. Orbital floor fracture greater than 50% and IMS involvement were much less accurate in making similar predictions. Cranial-caudal discrepancy should be used by the ED physicians to identify those patients who should be referred sooner than later to an oculoplastic surgeon for surgical evaluation and intervention. Correct and timely triaging can prevent the complications of delayed correction including scarring, difficult surgical repair, and/or poor functional and aesthetic outcomes.

? Meeting presentation: Not applicable.

?? Financial support: None to disclose.

? Proprietary interest statement: None of the authors have any financial interest related

to the manuscript in any manner.

* Corresponding author at: Department of Ophthalmology, Division of Oculoplastic and Reconstructive Surgery, The George Washington University, Washington, DC 20052. Tel.: +1 202 256 3361 (Mobile); fax: +1 703 875 9215.

E-mail address: [email protected] (T.N. Mansour).

Introduction

Patients with orbital fractures make up a significant percentage of those evaluated in the emergency department for facial trauma. All these patients require ophthalmic consultation but some more urgently than others. In our experience, only a fraction of these patients will likely require immediate ophthalmological consultation

http://dx.doi.org/10.1016/j.ajem.2016.10.030 0735-6757/

for possible surgical correction. Most patients can be observed without any surgical intervention with follow-up to an orbital trauma specialist within 7 to 10 days. Those requiring surgical correction typi- cally present with some or all of the following symptoms: persistent diplopia within 30? of center vision, functional or aesthetically signifi- cant enophthalmos, and orbital muscle/tissue entrapment with or with- out bradycardia and constitutional symptoms such as nausea and dizziness. Decreasing time elapsed between patient presentation and surgical intervention can improve the long-term outcome as scarring has yet to fully develop, which would make surgery more difficult [1-3]. Computed tomographic findings suggestive of orbital floor frac- tures (BOFs) spanning greater than 50% of the orbital floor (BOF N 50%) is considered the most predictive imaging sign that could help identify those patients whom surgical correction is required in the adult popula- tion group [1]. Clinically, many patients with the CT finding of BOF N 50% do not have a clinical presentation that would require them to under- go surgical correction. This observation has led us to question the accura- cy and reliability of the current imaging guidelines as a predictor of

severity of the orbital fracture and the need for earlier surgical repair.

In surgical patients, we observed that the portion of the orbital floor at the midlevel of the inferior rectus (IR) muscle is invariably involved. This observation led us to the hypothesis that a simplified means of identifying those fractures primarily involving this portion of the floor will help us predict symptomatic patients that will most likely require surgical correction. In other words, the location of the floor fracture along with the degree of displacement of the BOF (resulting in greater Volume expansion) determines how much instability within the orbital cone ensues after trauma. In this report, we define a reproducible and simple measurement that can predict long-term outcome in patients with BOF. We tested the hypothesis that the difference in the cranial- caudal dimension (CCD) of the fractured side as compared with the noninjured side at the level of the orbit just posterior to the globe can provide a reasonable approach to identifying patients in need of surgical intervention.

Methods

In this institutional review board-approved retrospective study, pa- tients who presented to a level I trauma center between 2011 and 2015 with an acute unilateral BOF with or without a small medial wall frac- ture were included. Patients were excluded if they had CT signs of bilat- eral orbital fractures, large medial wall fracture, complex Facial fractures, or muscular entrapment. In addition, those patients with in- adequate follow-up with an ophthalmologist were also excluded.

Two reviewers, a neuroradiologist and an oculoplastic surgeon, who were blinded to the patients’ outcomes, were asked to evaluate the BOF using 3 techniques. Orbital floor fracture greater than 50% was defined as a BOF that measured greater than 50% of the size of the orbital floor

in either axial, coronal, or sagittal plane. The inferomedial strut (IMS) was noted to be either involved or not involved in the fracture. Any ro- tation along the z-axis of the coronal plane of the CT scan was noted as positive involvement of the IMS. To calculate CCD, the reviewers were asked to follow the instructions outlined in Fig. 1. These steps guided the reviewers to measure the CCD of the orbit at a site in which the po- sition of the globe would most likely be altered by the displaced BOF fragment (area where the IR is thickest in vertical diameter). We pre- dicted that such alteration, if significant enough, would destabilize the orbit enough to necessitate surgical intervention.

The electronic medical record of the patient’s first encounter with an ophthalmologist, an oculoplastic surgeon in most cases, after his/her initial visit to the emergency department was reviewed. The patient’s ocular status at the time of this First visit (usually within 5-14 days of the trauma) was noted for any symptoms such as ocular pain, nausea or vomiting, and any signs such as periocular swelling, enophthalmos, diplopia, and/or limitation of ocular motility. If this information was not available, the patient was excluded from the study. Whether or not the patient underwent surgery was also noted but blinded from the authors at the time of their calculations of the CCD. Patients with clinically significant diplopia and/or aesthetically disturbing enophthalmos were chosen for surgical repair. Statistical analysis was performed using SAS 9.3 (SAS Institute, Cary, NC). Line plots were drawn using Excel (Microsoft, Redmond, WA).

Results

Thirty-three patients fit our inclusion criteria. There were 21 men and 12 women. Twenty-six patients suffered from an isolated BOF, whereas 7 patients had a concomitant minor medial wall fracture.

Of the 33 patients, 25 had BOF N 50%, 7 with fractures less than 50% and 1 patient with a fracture of about 50%. No patients with fractures of 50% or less underwent any surgery. Eight patients of the 25 with BOF N 50% ultimately underwent surgery. In other words, approximately one- third of those with BOF N 50% had surgery. Based on size of BOF, sensi- tivity was noted at 100%, whereas specificity was only 32%. The negative predictive value (NPV) was 100%, whereas positive predictive value (PPV) was noted at 32% (Fig. 2).

Twelve patients were found to have IMS involvement. Of those 12 patients, 6 ultimately underwent surgery. Sensitivity and specificity were noted to be 75% and 74%, respectively. Positive predictive value was 50% and NPV was 89% (Fig. 3).

Using average CCD, a cutoff of 0.8 cm was defined as threshold mea- surement differentiating between the group of patients requiring time- ly surgery and those that do not require surgical intervention. It was found that all 23 patients who had a calculated CCD of 0.8 cm or less did not ultimately require surgery. This resulted in a sensitivity of 100% and a NPV of 100%. Of the patients with a CCD of greater than

A

B

Fig. 1. Cranial-caudal dimension of the orbit. Computed tomographic scan of the orbit in bone algorithm in coronal view (A) at the posterior aspect of the globe defines the level at which the caudal cranial dimension of the globe is measured in the sagittal plane (B). Arrow labeled IOC points to the inferior orbital canal. Arrow labeled IR point to the IR muscle. B, CT scan of the orbit in bone algorithm in sagittal view bisecting the segment of the IR shown in panel A shows the belly of the IR and the course of the IOC. In this view, a globe line is drawn perpendicular to the axis of the globe (thin white line). A line perpendicular to globe line is drawn such that it intersects the posterior aspect of the globe (thick white arrow). The difference between this CCD of the orbit with an acute floor fracture from the normal side CCD is calculated. In patients with BOFs requiring surgical repair, the CCD measures greater than 0.8 cm.

BOF >50% Test Predictiveness of Surgery

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Average CCD Test Predictiveness of Surgery

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20 20

15 15

Number of Subjects

Number of Subjects

Positive Test

10 Negative Test 10

Positive Test(>0.8)

Negative Test(<0.8)

5 5

0

Yes No

Underwent Surgery

0

Yes No

Underwent Surgery

Fig. 2. Test predictiveness of surgery using greater than 50% floor fracture size.

Fig. 4. Test predictiveness of surgery using CCD calculation.

0.8 cm, 8 patients underwent surgery, whereas 2 did not, resulting in a specificity of 92% and a PPV of 80% (Fig. 4).

Given the accuracy in using the CCD to predict the likely need for surgery, interreader variability was measured to assess reproducibility. Using CCD measurements taken individually by both the neuroradiolo- gist and oculoplastic surgeon, the authors were able to confidently pre- dict the need for surgery. Taheri prediction resulted in a sensitivity of 100%, specificity of 92%, PPV of 80%, and NPV of 100%. Mansour predic- tions resulted in a sensitivity of also 100%, specificity of 96%, PPV of 89%, and NPV of 100%. Therefore, both authors were able to accurately pre- dict which patients would not likely require surgery. ? Agreement be- tween Taheri and Mansour with 95% confidence interval was noted at 0.9262. Test predictiveness of surgery by both authors is pictorially depicted in the both Figs. 5 and 6.

At the time of the initial clinical examination of the surgical candi- dates, 1 patient exhibited significant enophthalmos with no other find- ings, 2 exhibited enophthalmos as well as diplopia, and 5 complained of only Double Vision and were not found to have enophthalmos.

Discussion

It is well established that blunt trauma to the eye results in an anterior-posterior force that causes a buildup in orbital pressure through the orbit [4]. This pressure is subsequently released with the blow-out of one or more of the orbital walls, most commonly the orbital floor and then the medial wall. This mechanism protects the eye and the brain from further injury in many instances.

It is also well established that orbital fractures may need surgery within the first 1-2 weeks to avoid difficult repair, further muscle

IMS Test Predictiveness of Surgery

25

damage from ischemia, better functionality, and overall improved aes- thetic results [5-7]. The exact timing has been an ongoing debate and al- though some authors article have advocated early surgery (within 1-2 weeks), others have noted no difference in repair outcomes if per- formed later between 2 and 4 weeks [8]. Proponents of early surgical in- tervention suggest early surgery to prevent scarring or ischemia from playing a factor in outcomes. On the other hand, delayed surgery advo- cates suggest waiting to allow the orbit time to “decompress” from the build-up pressure to adequately assess the need for surgery. Only then will adequate clinical judgment be made and perhaps spare the patient unnecessary surgery. However, it is well established that delayed repair (between 2 and 4 weeks) can result in scarring and potentially compli- cate any surgical attempts. Most studies will agree that delayed repair is more technically challenging, albeit generally effective [8].

Previous studies have used CT data to predict delayed onset of enophthalmos [9,10]. Others have attempted to correlate postoperative ocular motility deficits after trauma and in the process developed a categorization of fracture types to predict those at greater risk [11]. In- dications of the need for early surgical intervention have also been stud- ied. Banerjee et al [12] looked at the rounding of the IR muscle in the orbital fracture as an indication of periorbital disruption and possibly a predictor for the need for early surgical repair to prevent delayed enophthalmos. Higashino et al [13] looked at orbital floor size and orbit- al volume analysis from CT scans to better predict the patients’ progno- sis as it relates to enophthalmos primarily. They came up with a treatment algorithm for orbital fractures based on CT scan findings pri- marily looking at the fracture width and the degree of protrusion of the IR muscle into the maxillary sinus [13]. Schouman et al [14] also found

R.T. Test Predictiveness of Surgery

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20 20

Number of Subjects

Number of Subjects

15 Positive 15

Test(IMS inv)

10 Negative 10

Test(No IMS)

Positive Test Negative Test

5 5

0

Yes No

Underwent Surgery

0

Yes No

Underwent Surgery

Fig. 3. Test predictiveness of surgery using +-IMS involvement. Fig. 5. Reza Taheri test predictiveness of surgery using calculated CCD.

T.M. Test Predictiveness of Surgery

30

25

Number of Subjects

20

15

10

5

0

Yes No

Underwent Surgery

Positive Test

Negative Test

of IMS involvement, our study did not demonstrate a high sensitivity or specificity and with a PPV of only 50%.

The concept of CCD came to fruition as we considered the orbit as a 30-cc shot glass or cone with the globe resting on the bottom of the glass cushioned by the IR muscle and orbital fat. Intraoperatively, we in- variably observe that the orbital floor is involved at the midlevel of the IR muscle regardless of size. Hence, we speculated that the exact loca- tion of the fracture may be as important if not more important that its dimension. Also observed is a greater degree of displacement of the or- bital floor and intraorbital contents. Technically, we know that the floor of this cone measures approximately 45 mm in length. The IR muscle, which is affected in isolated BOFs, is approximately 40 mm in length. The thickest part of the muscle tends to be at the level just behind the eye or somewhat midway along the floor of the orbit. This would be at approximately 22.5 mm from the inferior orbital rim. The location (the “sweet spot”) of the orbital floor “break,” which we suggest is just beneath the thickest part of the IR muscle, in addition to the degree

Fig. 6. Tamer Mansour test predictiveness of surgery using calculated CCD.

that the severity of the IR muscle displacement into the maxillary sinus was the most important predictive radiologic factor in management de- cision making.

Similar to the study by Schouman et al, Zhang et al [15] also looked at enophthalmos predictability by suggesting that the overall volume of herniated orbital contents correlated significantly with the amount of enophthalmos. The idea is that if a model can be developed that predicts enophthalmos severity, then one could also justify the need for more immediate or early surgical intervention even if enophthalmos is not significant early-on.

Our current methods of CT scan examination to predict the likeli-

hood of surgical intervention have not reached an adequate consensus. Simply looking to see if the BOF is greater than 50% is not adequate as many of the classic textbooks seem to suggest. Our study shows that many patients who have greater than 50% BOFs do not require surgery (specificity of 32% and 32% PPV). A recent study by Vicinanzo et al [16] suggests that considerable interreader variability in CT measurements of BOFs can make this measurement even less accurate and reliable. They conclude that clinical findings are more dependable than radiographical measurements.

The importance of the IMS as a possibly overlooked radiographic en- tity was entertained based on studies involving thyroid decompression. It is well known that the IMS is a thick strut of bone that provides sup- port for the medial orbit [17]. In Decompression surgery, it is widely rec- ommended that the anterior portion be left intact to reduce the incidence of globe dystopia and, hence, diplopia. With this in mind and having not been studied before, the idea of a fractured and displaced IMS as a possible risk factor for ensuing diplopia after trauma was examined. All scans were examined for any displacement of the IMS along the z-axis. Despite the theoretical validity of the importance

of inferior floor displacement (volume expansion) is what causes the greatest amount instability of the orbital contents and globe. This can result in enophthalmos/globe ptosis and/or restriction. Because it is not practical or likely adequate to measure the area of the irregular floor defect, we set out to find a much more simplified and reproducible measurement. This measurement would have to be 2-dimensional and minimize interreader variability. The posterior aspect of the globe that is perpendicular to what is typically indicated as the z-axis (anterior- posterior) was found to be roughly midway along the orbital floor and in the area where the IR muscle is thickest. By looking at our patient’s CCD data plotted on a line graph, we noted a point or measurement above which all our patients underwent surgery and under which all our patients did not have any surgery. This number was found to be

0.8 cm and was the number that we believe is a critical difference that if determined in any isolated BOF patient will help to indicate urgency of surgical intervention. There is a direct correlation of CCD with the de- gree of inferior floor displacement and therefore the likely amount of orbital volume expansion as well. The higher the CCD value, the greater the newly created orbital volume. Likewise, we can infer that there is some percent change in orbital volume, if located just beneath the thickest part of the IR muscle, and it will more than likely result in enophthalmos/globe ptosis and/or restriction necessitating early surgi- cal intervention. Currently, a prospective study noting the validity of this 0.8 cm CCD value is underway.

In the 33 patients who met the inclusion criteria, it was found that any value greater than 0.80 cm in the CCD was a significant enough ra- diologic finding that warranted surgery every single time. This differen- tial, greater than 0.8 cm, was just enough to create visually significant and debilitating instability of the globe. It was also found that interreader variability was not an issue as noted by a high ? agreement between Mansour and Taheri. The high sensitivity, specificity, and NPV and NPV demonstrate the benefit of using the CCD in assessment of

A

B

Fig. 7. Craniocaudal differential (CCD). The orbital fracture of these patients measures greater than 50% of the floor, which typically would require surgical repair. After a physical examination by an ophthalmologist, a surgical repair was deemed unnecessary. Application of the CCD, which is obtained by calculating the difference between the caudal and cranial dimension of the orbit with the floor fracture (3.75) (A) from the normal side (3.28) (B), measures 0.47 cm that is below a threshold needed for surgical repair (noted at 0.8 cm).

simple orbital fracture cases. This measurement can expedite consulta- tion with the appropriate subspecialists for more prompt and effective surgical intervention. This point cannot be further underscored because a few of the initial clinical examinations in our studies were seen by ophthalmology specialists who do not perform orbital fracture surgery. Many of the patient’s evaluations in the emergency department were inadequate to reliably predict the possibility of surgery because of fac- tors such as extensive periorbital edema, subconjunctival hemorrhage, retrobulbar hemorrhage, and poor patient cooperation. This ultimately resulted in subsequent referral delays to oculoplastic specialists which risks delaying surgery.

Limitations of this study include the retrospective nature of the study and the relatively small sample size. To avoid measurements biases, the CT reviewers were blinded to the patients’ final outcome. It should also be noted that this measurement only applies to those patients with isolat- ed BOFs and those with concomitant minor medial wall fractures. Patient’s with obvious rectus entrapment noted on CT scan were exclud- ed and would not likely fit the criteria presented here. The study does not attempt to suggest whether or not enophthalmos alone or enophthalmos with diplopia is more likely to occur in these patients as some previous studies have attempted to elucidate.

Conclusions

The CCD maximizes our ability to identify the crucial area along the orbital floor that best predicts the largest, critical change in orbital vol- ume that will likely result in clinically significant enophthalmos and/or muscle restriction (example of calculation in Fig. 7).

The CCD is an accurate and reliable measurement that can differen- tiate between patients with acute BOF who require earlier surgical in- terventions and those who would not. This technique can be used by radiologists and especially emergency medicine physicians to help in timely referral to orbital surgeons to treat such patients as effectively as possible. Surgical timing appears to influence the complexity of the procedure and may ultimately determine the final functional and aes- thetic outcome(s). This tool may be of highest impact to those rural emergency physicians who do not have the luxury of having available specialists for on-site consultation.

Conflict of interest

The authors declare that they have no conflict of interest.

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