Traumatic orbital encephalocele: Presentation and imaging

Abstract

Orbital encephalocele is a severe and sight-threatening complication of orbital roof fractures. Post-traumatic orbital encephalocele can be challenging to diagnose on CT as patients with this condition often have associated orbital and intracranial hematoma, which can be difficult to distinguish from herniated brain tissue. When there is a high index of suspicion for encephalocele, an MRI of the orbits and brain with contrast should be obtained for additional characterization. Imaging signs that should raise suspicion for traumatic orbital encephalocele include an enlarging heterogeneous orbital mass in conjunction with a roof fracture and/or widening fracture segments.

Isolated orbital roof fracture: Can it be catastrophic?

“…[ 8 ] Many authors advised magnetic resonance imaging (MRI) of the orbit as the investigation of choice. [ 2 6 8 9 ] It may not be always easy to perform MRI in emergency situation. CT of the orbit with thin axial and coronal sections is very useful in the evaluation of the orbital contents.…”

Reconstruction of a Combined Frontal Bone and Orbital Roof Defect With Associated Meningoencephalocele Using 3D Modeling and 3D Navigation

“…The etiology of the meningoencephalocele was also due to a raised intracranial pressure causing the meninges and brain parenchyma to herniate through a large (3 cm by 2 cm) orbital roof defect; a finding also found by Wei et al, especially where the orbital roof defect exceeded 2 sq cm. 10 Although in our patient the intracranial pressure will have normalized by the time he presented to us, we suspect the meninges and extraconal tissue in the superior orbit were in contact with each other for long enough for them to fuse, leading to tethering and pain. With this is mind, we recommend that any repair of an orbital roof fracture should serve to prevent transmission of intracranial pressure into the orbit and introduce a barrier to separate 1 cavity from another.…”

“…15,16 Development of a meningoencephalocele through a traumatic orbital roof defect is not inevitable, but the clinical signs that raise suspicion are progressive pulsatile exophthalmos with evidence of globe or optic nerve compression, while the radiological signs on CT are an enlarging heterogeneous orbital mass with associated widening of the roof fracture segments. 10 Cayli et al suggested a fracture diastasis greater than 2 mm increases the propensity to brain herniation in the pediatric patient population, 16 and the concept of a skull base fracture growing wider as the child grows can explain why some meningoencephaloceles develop years after the initial injury. 6 Although much more unusual this phenomenon has also been described in an adult.…”

“…17 To access the orbital roof 2 main approaches are described, the upper eyelid incision and the coronal flap. 10,28,29 Given the need to access the frontal lesion and associated bony defect in this patient, we assessed the coronal flap to be most suitable. In isolated orbital roof fractures, particularly those complicated by a CSF leak requiring dural repair, a craniotomy is required, but in this patient the frontal bony defect served as an access point to deal with both the meningoencephalocele and orbital roof defect simultaneously, even though it had to be enlarged.…”

“…Most orbital roof fractures can be managed nonoperatively if asymptomatic and minimally displaced, 11 but exophthalmos, particularly if it is pulsatile or expanding, is a potential sign of a meningoencephalocele and may be associated with a reduction in visual acuity. 8,10 If this is the case then some form of operative intervention is required to salvage the vision, but treatment strategies are disparate. Furthermore, if there is a concomitant cerebrospinal fluid (CSF) leak secondary to a dural tear, then the risk of meningitis is increased and the need for surgery is reinforced.…”