PMC4722521_01
(a and b) The immediate postinjury thin-slice computed tomography scan with coronal reconstruction showed generalized brain edema without left orbital roof fractures. (c) Computed tomography scan 24 h after trauma revealed a left-sided frontal contusion causing midline shift and increased diffuse brain swelling. (d and e) Postoperative computed tomography scan showing left decompressive craniotomy and evacuation of frontal contusion with a small bony defect in the roof of the orbit (see arrow) probably related to an unintentional opening of the orbit during keyhole burr hole without evidence of encephalocele. (f) Computed tomography scan after cranioplasty confirming the small bone opening on the orbital roof (see arrow)
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The immediate postinjury computed tomography (CT) scan showed only a mild, diffuse brain swelling [Figure 1a]. Thin-slice CT scan with three-dimensional (3D) reconstruction and coronal and sagittal sections did not show skull base fractures, in particular, posttraumatic bony defects on the left orbital roof [Figure 1b]. Hence, she repeated immediately a CT scan that revealed a massive increment of the brain swelling, and a left-sided frontal contusion causing contralateral midline shift [Figure 1c]. The immediate postoperative CT scan confirmed evacuation of left posttraumatic hemorrhage and resolution of the mass effect [Figure 1d]. At a deeper examination, this exam also showed a small bony defect on the orbital roof, undetected until the occurrence of the orbital encephalocele (see the arrow in Figure 1e). Wound healing was uneventful, and postoperative neuroimaging showed accurate fitting of cranioplasty, along with the undetected bony defect of the orbital roof [Figure 1f].
(a-c) Thin-slice orbital computed tomography sections with three-dimensional and coronal reconstruction (2 years after the cranioplasty) revealed the enlargement of the lateral orbital roof bony defect associated with intraorbital encephalocele. The arrow indicates the burr hole, filled by autologous bone dust mixed with a bone substitute, too close to the orbital wall. (d) Magnetic resonance imaging image confirming the herniation of brain matter into the left orbit
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However, a thin-slice orbital CT sections with coronal reconstruction revealed the enlargement of the supero-lateral orbital roof defect with intraorbital encephalocele [Figure 2a-c]. Magnetic resonance imaging (MRI) confirmed the herniation of brain parenchyma into the left orbit through that bony defect [Figure 2d].
Abcdefghi: Intraoperative images and postoperative thin-slice computed tomography scan with three-dimensional reconstruction. (a) Left superior blepharoplasty incision. (b and c) Supra-transorbital keyhole approach with the combination of an orbital osteotomy with a supraorbital minicraniotomy. The use of piezoelectric scalpel allows to realize precise and thin osteotomies, for better future bone healing and better aesthetic result. (c and d) The one-piece bone flap includes the frontal bone, and the orbital rim using the defect of the orbital roof as the posterior edge of the orbitotomy. The one-piece bone flap was then fixed by titanium low-profile miniplate and screws. (e) Intraoperative working area with the exposure of both orbital and intracranial compartments. (f-i) Postoperative thin-slice computed tomography scan with three-dimensional reconstruction and magnetic resonance imaging showing left orbital roof reconstruction with autologous bone, obtained from the split calvarial parietal bone contralateral to the cranioplasty
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The piezoelectric bone scalpel (piezosurgery) was used to perform a small supraorbital keyhole craniotomy including the supero-lateral orbital rim in one piece using the defect of the orbital roof as the posterior edge of the orbitotomy [Figure 3a-e]. This combined minimally invasive approach gave access to both the superior orbital cavity and the intracranial supraorbital anterior skull base without the need for cranioplasty to be removed [Figure 3e]. Then, the orbital roof was reconstructed with autologous bone, obtained from the outer bone parietal layer contralateral to the cranioplasty through a small linear skin incision and fixed by titanium low-profile miniplate and screws [Figure 3c, d, and f-h]. The thin bone cutting line, performed by piezoelectric scalpel, allowed a perfect realignment of bone stumps [Figure 3c]. Postoperative thin-slice 3D CT scan showed the stable reconstruction of the orbital roof and good restoration of roof contour and normal orbital volume, excluding intracranial complications [Figure 3f-h]. MRI images 2 months after surgery confirmed the complete reduction of encephalocele [Figure 3i].