Indications
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Frontotemporal craniotomy with orbitozygomatic osteotomy is an adjunct to pterional craniotomy that allows greater rostral trajectory to midline structures. By removing the superior and lateral bony orbit, one gains a more anterior and inferior starting point for the approach than would be possible with a conventional pterional craniotomy.
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Removal of the zygomatic arch enables inferior displacement of the temporalis muscle, allowing for a lower starting point for subtemporal visualization.
Planning and positioning
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The exact positioning needs vary by case. The patient generally is placed supine on the operating table.
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The head is placed in a Mayfield head holder with two pins placed in the occiput just off the midline. The single pin is placed in the contralateral forehead, in the mid-pupillary line ideally behind the hairline.
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After pinning, the head is usually positioned such that the lateral orbital ridge and keyhole region is the highest point on the patient’s head. This position is achieved by about 5-1 degrees of contralateral head rotation and a slight degree of neck extension and head elevation.
Figure 15-1:
Positioning the patient and head. The patient is placed supine on the operating table with the ipsilateral shoulder elevated as needed to facilitate head rotation toward the contralateral side. The skull clamp is fixated with the paired posterior pins at the equator in the occipital bone and the single anterior pin at the equator in the contralateral frontal bone superior to the orbit. The head is positioned by first elevating the head above the heart in the “sniffing position.” Second, the head is rotated up to 30 degrees to the contralateral side depending on the intended operation. Third, the neck is extended so that the vertex is angled down 10 to 30 degrees, allowing for self-retraction of the frontal lobe off the anterior cranial fossa floor. When the head is ideally positioned, the malar eminence of the zygomatic bone should be the highest point in the operative field.
Procedure
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In the suprafascial approach, sharp dissection is used to create a plane beneath the fat pad and above the temporalis fascia. Blunt dissection is used to reflect the fat pad and scalp over the lateral orbit and maxilla until adequate exposure is obtained.
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In the subfascial approach, as soon as the fat pad is visualized, the temporalis fascia is elevated off the superficial surface of the muscle with scissors and is separated from the bone of the lateral orbit, maxillary buttress, and zygomatic arch with a small periosteal dissector. The scalp and fat pad are reflected anteriorly with the temporalis fascia to enter the lateral orbit.
