138 |
8 Surgical Repair of Craniofacial Fractures |
|
|
Fig. 8.8 Coronal approach: planes of dissection to the zygomatic complex (mod. a. Kellman and Marentette 1995). The subgaleal dissection over the temporal muscle continues epifascially on the surface of the STF and stops superiorly to the temporal line of fusion of the superficial and deep layer of the DTF in order to preserve the frontal branch of the facial nerve. The superficial temporo-parietal fascia is incised, and dissection continues under the SFT fascia. Below the temporal line of fusion, the dissection has to be done directly under the superficial layer of the DTF
8.4.2.2 Osteoplastic Craniotomy
A classical approach to the frontal skull base can be gained by a unior bifrontal craniotomy (Unterberger 1959; Schmidek and Sweet 1988; Imhof 2000). This approach enables the surveillance of the entire anterior skull base, including the orbital roofs, cribriform plate, ethmoid, and frontal sinuses. The drill holes are positioned individually according to the line of fracture. The craniotomy is either bifrontal-symmetrical or in favor of the more affected side.
The craniotomy holes should be connected in such a way that the parasagittal holes are connected last, so that in case of an iatrogenic or existing injury to the superior sagittal sinus, access to the sinus is assured within a short time. It is necessary to carefully and subtly release the dura with special dissectors before lifting the depressed fragments, to avoid tears to the dura and the venous drainage system (Figs. 8.12–8.14).
Hemorrhage originating from the venous sinus system is primarily best controlled digitally. Subsequently the defect is sealed by compression through a muscle patch, which is secondarily reinforced by bridging sutures and application of fibrin glue.
Using the intradural access, an additional bore hole to the temporal bone and to the superior temporal line not only enables the inspection and revision of the inferior surface of the frontal lobe from anterior, lateral, and from the wing of the sphenoid bone but also that of the optic nerve, internal carotid artery, basal cisterns and the orbital fissures as well as the temporal pole and the inferior surface of the anterior third of the temporal lobe (Imhof 2000).
• Frame-like craniotomy
After detaching the pericranium, four bore holes are drilled around the fracture site. The dura between the burr holes is separated from the internal table with a
8.4 Transfrontal-Transcranial \Approach |
139 |
|
|
Fig. 8.9 Coronal approach: exposure of the zygomatic complex (mod. a. Kellman and Marentette 1995). (a) The superficial layer of the DTF is incised at the root of the zygomatic arch. The incision continues at an angle of 45° until it joins the cut edge of the pericranium flap. To facilitate exposure of the zygomatic arch, a preauricular extension of the incision can be performed. (b) Incision of the superficial layer of the deep temporal fascia exposes the superficial temporal fat pad. The dissection is then carried out inferiorly between the fascia and superficial to the fat pad until the zygomatic arch and the posterior border of the zygoma are reached. This plane of dissection provides a safe route to the zygomatic arch because the temporal branch of the facial nerve is retracted laterally with the superficial layer of the deep temporal fascia. (c) The zygomatic arch is initially approached at its root, where the periosteum is incised along the superior border. The incision continues anteriorly along the posterior border of the zygoma and reaches the cut edge of the pericranium flap. (d) A subperiostal dissection is then performed, which exposes the lateral surface of the zygomatic arch, the body of the zygoma and the lateral orbital rim
(e) Intraoperative situation (arrow: diagonal line of incision in the superficial layer of the deep temporal fascia (DTF))
a |
b |
c |
d |
e
STF
DTF
narrow, blunt dissector and the fractured calvarial bone plate is sawed out with a ‘Gigli’ saw, mobilized, and removed. Bone dust is collected (Imhof 2000).
• Initial fragment stabilization
In polyfragmentation without dislocation of the frontal calvarium, stabilization of the calvarian pieces with miniplates should antecede a craniotomy. If bone
transplants are necessary to cover defects, lamina interna bone grafts can be gained from the craniotomized and split bone cap.
• Mobilization from within a bore hole
If large pieces of the calvarium are impressed and the fragments difficult to mobilize, then a hole is drilled on the outer area of the fracture site and widened
140 |
|
8 Surgical Repair of Craniofacial Fractures |
|
|
|
a |
b1 |
b2 |
Fig. 8.10 Coronal approach: exposure of the zygomatic complex. (a) Incision of the superficial layer of the DTF at a 45° angle and subfascial dissection superficial to the temporal fat pad.
(b) After incision of the periosteum the zygomatic arch is exposed in a subperiostal plane
Fig. 8.11 Coronal approach: exposure of the pterional region. Incision and elevation of the temporal muscle to expose the pterional region
osteoclastically (with a rongeur) up to the edge of the impressed region. Working from the drill hole, one of the nearest fragments can be separated from the dura, mobilized, and removed. This process is repeated for the remaining fragments.
All fragments are carefully preserved, reassembled exactly outside the operative field and stabilized with miniplates to be reintegrated later as a calvarian trans plant.
• Extension osteotomies
For an improved frontobasal exposure, additional frontofacial segments can be osteomized to facilitate a direct
base-parallel approach (Hardt et al. 1992).These frontofacial osteotomies can vary due to location and extent of the fracture site.
Frontal extension - osteotomy
•Applying vertical and horizontal frontofacial osteotomies with a micro-saw
•Removal of the cranio-frontal or entire frontofacial segment
By selectively osteotomizing the cranio-orbital or cranio-frontal bone compartments (supra-orbital