The cranio-orbital–zygomatic (COZ) approach is the most versatile approach that can be used on selective cases of giant extensive chordomas that otherwise might need more than one approach or are difficult to reconstruct. It allows the radical resection 1,2 of lesions originating in the upper clivus and extending laterally to the internal carotid artery, middle fossa, petrous apex, infratemporal fossa, retropharyngeal, and into the sphenoid sinus. Furthermore, it is ideally suited for following chordomas from their extradural origin intradurally, which can occur in up to 48% of chordomas 3 ( ▶ Fig. 17.1, ▶ Fig. 17.2, ▶ Fig. 17.3). In the ZOC approach, the resection of part of the orbital roof provides clear advantages when exposing certain lesions in the anterior and middle cranial fossa. The mobilization of the zygomatic arch allows access to the middle fossa without temporal lobe retraction, infratemporally, and the sphenopalatine fossa. The posterior fossa can be accessed by drilling the petrous apex. The sphenoid sinus can be entered both superiorly through the planum sphenoidale and laterally in between the trigeminal divisions. The upper clivus can also be reached, as in a transbasal approach. The orbital flap removal can be done in a separate manner, with or without the zygomatic arch attached to it, or can be elevated with the frontotemporal flap. The latter provides a better cosmetic result and makes further reconstruction of the orbit unnecessary. The many advantages of the COZ approach include:
Minimizing brain retraction by removing the orbital roof and mobilizing the zygomatic arch, providing access under the frontal and temporal lobes.
Shortening the distance between the superficies and the targeted lesion.
Accessing multiple surgical corridors, providing multidirectional viewing and surgical possibilities.
Intra- and extra-dural access for chordomas involving both compartments.
Tailoring the size of the flap to encompass the extension of the lesion.
Accessing the infratemporal fossa, sphenopalatine fossa, retropharyngeal space, and paranasal sinuses, including ethmoid, sphenoid, and maxillary.
Provides proximal and distal control of the petrous and cavernous carotid artery.
Providing vascularized tissue to repair defects on the floor of the anterior and the middle cranial fossa.
Eliminating the bone reconstruction with the single cranial flap.
Excellent cosmetic results.
Fig. 17.1 (a) Preoperative sagittal enhanced MRI showing a large clival chordoma and (b) postoperative MRI showing its complete removal through a COZ approach and reconstruction of the skull base defect with a vascularized perincranial graft. (Images courtesy of Dr. Ossama Al-Mefty’s educational collection.)
Fig. 17.2 (a) Axial, (b) sagittal, and (c) coronal preoperative MRI showing a large chordoma extensively involving the clivus, cavernous sinus, paranasal sinuses, infratemporal fossa, and retropharyngeal space. (d) Postoperative coronal MRI showing an extensive resection from each involved compartment through a single COZ approach. (Images courtesy of Dr. Ossama Al-Mefty’s educational collection.)
Fig. 17.3 (a) Axial and (b) sagital preoperative MRI showing a large chordoma extensively involving the clivus, cavernous sinus, paranasal sinuses, infratemporal fossa, and retropharyngeal space. (c) Axial and (d) sagittal postoperative MRI showing the tumors’ complete resection through a single COZ approach with reconstruction of the middle fossa floor using the temporalis muscle. (Images courtesy of Dr. Ossama Al-Mefty’s educational collection.)
A lumbar drain is placed for cerebrospinal fluid (CSF) drainage, preferably through a split mattress with a small-gauge needle. CSF is slowly drained after the cranial flap is elevated. The patient is positioned supine, with the upper body slightly elevated and the head rotated 30 to 45 degrees to the contralateral side depending whether the expected work is more anteriorly or laterally ( ▶ Fig. 17.4). Leads to monitor somatosensory evoked potentials, brainstem auditory evoked potentials, and cranial nerves V and VII are placed at this time, with those to monitor cranial nerves III, IV, and VI placed following removal of the orbit. The ipsilateral neck is included in the prepped field should more proximal carotid control be required, and the abdomen is prepared for fat graft harvest. Intraoperative neuronavigation is always used, and excellent registration accuracy is ensured.
Fig. 17.4 Patient positioning for COZ craniotomy with the lumbar drainage tubing through the split mattress. (Illustration courtesy of Dr. Ossama Al-Mefty’s educational collection.)
The skin incision for the COZ starts at the zygomatic root and is carried behind the hairline toward the contralateral superior temporal line ( ▶ Fig. 17.5). The superficial temporal artery is identified and carefully protected, and a large pericranial flap is raised by undermining the scalp posterior to the incision and dissecting sharply against the scalp flap anteriorly. In chordomas, in particular, the raising of the pericranial flap is critical in this approach because it provides an outstanding vascularized reconstruction after entry into the air sinuses. A subfascial dissection of the temporalis fascia is performed to preserve the frontal branches of the facial nerve ( ▶ Fig. 17.6). The zygomatic arch and superior and lateral orbital margins are exposed by subperiosteal dissection, after which the zygoma is divided at either end and displaced inferiorly on its masseteric pedicle. The temporalis muscle is then elevated in subperiosteal fashion, beginning low on the temporal squama and proceeding superiorly to detach the muscle at the superior temporal line. The entire temporalis muscle is then reflected inferiorly with the freed zygoma.
Fig. 17.5 Skin incision as depicted by the dashed line for COZ craniotomy. (Illustration courtesy of Dr. Ossama Al-Mefty’s educational collection.)