British Journal of Radiology (2007) 80, e247-e249
© 2007 British Institute of Radiology
doi: 10.1259/bjr/77061359
Tomographic findings in traumatic globe evulsion caused by blunt head trauma
E Roldan-Valadez, MD
1
R Corona-Cedillo, MD
2
C Rojas-Marin, MD
2
G Valdivieso-Cardenas, MD
2
J M Sanchez-Sanchez, MD
2 and
H Quiroz-Mercado, MD
3
1 Magnetic Resonance Unit, 2 Department of Radiology, 3 Ophthalmology Unit, Medica Sur Hospital and Clinical Foundation, Mexico City, Mexico
Correspondence: Dr Ernesto Roldan-Valadez, Magnetic Resonance Unit, Medica Sur Hospital and Clinical Foundation, Puente de Piedra #150, Col. Toriello Guerra. Delegacion Tlalpan, CP 14050, Mexico City, Mexico. E-mail: ernest.roldan{at}usa.net
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Abstract
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Evulsion of the globe as a result of trauma is a rarity; to the best of our knowledge, only four "evulsions of the globe" have been described. We present the case of a 35-year-old Hispanic woman with traumatic evulsion of the right eye and subarachnoid haemorrhage. The management of brain injury was the priority over preservation of globe structures. We briefly describe the tomographic features of this uncommon situation and the proposed "evulsion" mechanism.
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Introduction
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Evulsion of the globe as a result of trauma has seldom been described in the medical literature [1–4]. Autoenucleation by psychiatric patients, although rare, appears to be more commonly reported than traumatic removal of the eye as a result of an accident or assault [5]. Evulsion is defined as "extraction by force" and it means "the tearing away of a part of a structure" [6]. To the best of our knowledge only four "evulsions of the globe" have previously been described [6, 7]. The purpose of this report is to present the main imaging features in this uncommon situation as well as a proposed hypothetical evulsion mechanism.
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Case report
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A 35-year-old Hispanic woman was referred to the emergency room with loss of consciousness. A witness reported that while the woman was eating in a highway restaurant a car crashed into the restaurant throwing her to the floor. She underwent right-sided facial trauma, striking her right orbit and evulsing the eye. On physical examination, the right eye was positioned outside the eyelid fissure on the malar eminence, hanging by a thin thread of tissue.
In view of the findings, a cranial helical computed tomography (HCT) scan was performed. HCT examination depicted the absence of the eyeball in the right orbit; it was situated outside the orbit with the optic nerve remaining inside (Figure 1a–d
). There was evidence of nerve sheath disruption in the intraorbital portion of the right optic nerve; detachment of the optic nerve and external orbital muscles at their points of insertion were seen. No signs of intraconal haematoma were noted. No fractures of the orbital walls were reported and the maxillary sinus was spared. The left globe was preserved. Additional findings included a small amount of blood in the ethmoidal sinus with extensive subarachnoid haemorrhage in the suprachiasmatic cisterns with fluid–fluid levels in the lateral ventricles (Figure 2a,b).
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Figure 1. Unenhanced CT.(a,c) Sagittal and axial plane multiplanar reconstructions showing the right globe hanging outside the orbit. There was nerve sheath disruption of the intraorbital portion of the optic nerve, with detachment of the optic nerve and external orbital muscles at their insertion points in the globe. (b,d) Sagittal and axial planes of the left globe show a normal appearance.
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Figure 2. Unenhanced CT.(a) Axial plane at the mid-orbit depicting the evulsed right globe. No signs of intraconal haematoma are noted and a small amount of blood in the ethmoidal sinuses is observed. (b) Axial plane, a slightly superior image, showing an extensive subarachnoid haemorrhage in the suprachiasmatic cisterns with fluid–fluid levels in the lateral ventricles.
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The patient was admitted to the intensive care unit for the management of the brain oedema and subarachnoid haemorrhage. An ophthalmological examination of the right eye 48 h after the accident revealed that there was no afferent reaction of the pupil to light, there was an interruption of the blood flow in all visible retinal vessels and the sclera was intact. Although the globe structures were preserved, the eye was removed because of the low probability of recovering visual function. The patient did well, recovering from the subarachnoid haemorrhage, and was discharged. She continues to be managed in the outpatient clinic.
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Discussion
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Although different external causes of eye injuries have been reported, injuries as a result of motor vehicle crashes predominate [6]. The extent of damage to the eye from trauma depends on the precise magnitude and direction of the external forces involved.
A hypothetical mechanism has been proposed to explain how the entire globe (leaving behind the optic nerve) is evulsed from the eye. It is believed that an impact site between the globe and the orbital rim is more likely to result in an evulsion of the globe and/or optic nerve such as that found in our case, whereas a direct blow to the eye is more likely to result in a ruptured globe [8].
The case presented here does not actually provide any additional evidence to support a particular mechanism of evulsion, as the precise direction and amount of force applied or the characteristic of the object striking the head of our patient could not be determined. Another witness to the accident said that an object on the lateral aspect of the truck hit the patient's face. One possible way in which this type of injury might cause the damage seen has been described by Morris et al [6]. In his hypothesis, the forcing of the straight-line edges of the object into the medial orbit creates a lever effect with the fulcrum at the anterior portion of the nasal bone (Figure 3). The posteriorly directed force vector created by the external force medial to this fulcrum is transformed into an anteriorly directed force vector behind the eye at the temporal end of the lever, forcing the globe anteriorly out of the orbit and disrupting the optic nerve in the manner depicted (Figure 1a–d
).
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Figure 3. Proposed mechanism of injury caused by an elongated object entering the orbit medial to the globe(axial plane), modified from Morris et al [6].
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Although the actual mechanism of globe evulsion in this case is hypothesized, without any real additional evidence to substantiate it, we agree with Morris et al [6] that (i) variations in the diameter of the optic nerve, (ii) the tensile strength of nerves and their sheaths, (iii) the thickness of the posterior sclera and optic nerve sheaths, (iv) the strength of the attachment of the nerve and sheath around the lamina cribrosa, (v) differences in the amount and angulation of the force encountered, (vi) characteristics of the object entering the orbit and (vii) the orientation of the patient's eye and orbit with respect to the oncoming object will all influence the exact impact point and precise direction of the vector forces that act on the patient's globe and optic nerve, thus determining the type of damage to the eye.
An interesting feature of this case was the preservation of globe structures. However, in this case the management of brain oedema and subarachnoid haemorrhage was the priority over globe preservation; because of the uncommonness of our case, the management of the globe as an initial step would not be advised. When a patient is admitted to a hospital with facilities for, and a surgeon trained in, eye microsurgery, a combined neurosurgical and ophthalmological team could work together to save life and preserve the globe.
Received for publication May 11, 2006.
Revision received July 26, 2006.
Accepted for publication August 16, 2006.
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References
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Abstract
Introduction
