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Medial Sphenoid Wing Meningioma: Orbitozygomatic Osteotomy

September 08, 2015


Let's review the details of the approach and microsurgical strategies for a section of large medial sphenoid wing meningioma. This is a 36 year-old female who presented with left sided visual field dysfunction, MRI evaluation revealed a relatively large medial or mid sphenoid wing meningioma. There was minimal amount of edema associated with this tumor. You can see the MCA branches draping over the superior pole of the tumor and the ICA, now significantly encased more medially. Let's go ahead and review the approaches and the basics of the patient positioning. But before doing so you can see an MRA demonstrates the typical, dislocation and stretching of the proximal MC branches, as well as the ICA around the medial aspect of the tumor. The CT scan is useful to determine if there is any high prosthesis of the client or what process or the sphenoid wing associated with the tumor. A normal puncture is quite useful, no matter how big is the size of a tumor because early relaxation or the brain are those aggressive devascularization of the tumorized space without significant debulking. This early devascularization significantly improves the efficiency of the resection and minimizes the amount of blood loss. Let's go ahead and review the basics for patient positioning and our orbital zygomatic craniotomy. You can see the pin placement in this case, since this tumor was extending more cranially or it was relatively high writing and orbitozaidal madicraniotomy appear to be useful to improve the inferior to superior operative trajectory. We'll see, during the intradural part of the procedure, if such decision was appropriate or not. Here's the incision just behind the hairline, extending all the way to the contralateral mid-pupillary line. The head has turned about 30 to 40 degrees. Minimum head shave is appropriate. The incision is well injected with the local anesthetic mixed with epinephrin solution after draping the incision. The incision is completed and Raney clips are applied. I use a relatively wide spatular to immobilize the scalp away from the superficial temporalis fascia. This maneuver almost invariably protects the superficial temporal artery and avoids any inadvertent injury to the soft tissues underneath The ST is then dissected and protected if possible. Sculp flap is reflected interiorly in a separate layer from the temporalis muscle. And this subfascial technique is used to mobilize the fat pad. Here you can see the superficial temporalis fascia effect pad, as well as the deep temporalis fascia are mobilized in a single layer. The branches of the frontalis nerve are essentially within the superficial layer of the temporalis fascia and not directly within the fat pad. The frontal process of the zygoma is exposed. Further exposure of this process is necessary for performance of the modified one piece orbital zygomatic osteotomy. The orbital rim is also dissected. You can see the frontal zygomatic suture. The supraorbital nerve is mobilized out of its groove. If there's a foramen present, a piece of the bone surrounding the nerve is disconnected and mobilized with the nerve. Here's further exposure of the frontal process of zygoma. You can see that small piece of bone encircling the supraorbital nerve was disconnected and mobilized with the nerve anteriorly. Here's disconnection of the temporalis muscle The muscle is mobilized inferioraly and slightly posteriorly. A keyhole is placed just a few millimeters above and posterior to the frontal zygomatic suture. You can see the 45 degree angle between the shaft of the drill and the surface of the skull. Another burr hole is placed more posteriorly just below the superior temporal line. Here's the first osteotomy. Here's the second osteotomy. Here's an osteotomy along the anterior aspect of the orbital rim. Another osteotomy along the frontal process of zygoma. The orbital roof is disconnected through the keyhole using a small osteotome. The one piece orbiter zygomatic bone flap is next elevated. The lateral aspect of the orbital rufous sphenoid wing are resected. Here's periorbital. You just remove all part of the lesser sphenoid wing. Frontal sinus was inspected. It's mucosa was removed and a piece of muscle was placed within the sinus during this procedure, it was later exonerated. Additional pieces of the orbital roof can be removed to expand our subfrontal operative trajectory. Here you can see the final extent of bony removal to provide an unobstructed inferior to superior subfrontal operative trajectory. Sutures are placed along the more deeper part of the dura to mobilize the orbit inferiorly. Depressing the orbit gently using these retention sutures, further expands the operative corridor. Here's the final product for the exposure. Here's the microsurgical part of the operation. The latter aspect of the tumor has been devascularized from the mid portion of the sphenoid wing dura. The tumor is next debulked heavily. You can see aggressive devascularization are those efficient debulking without much bleeding, the tumor is then mobilized from the frontal lobe and the sub-frontal area, VMC branches. And more so specifically their distal branches are identified early. Here you can see some of these branches. I continue to debulk the tumor, and mobilize the capsule. I may argue that the orbital zygomatic craniotomy may not be necessary in this case. Here again are the distal MCA branches within the fisher. Tumor capsule is being carefully mobilized in fragments. They're cells that directly lead into the tumor, are carefully inspected and subsequently coagulated and cut. Arachnoid planes over the cerebrovascular structures are carefully preserved. Here's the subfrontal portion of the tumor. There is a vessel directly entering the mass. No exiting vessel is apparent. Therefore the small vessel was coagulated and cut. Piecemeal tumor removal continues, here you can see MCA branches and the MC bifurcation, as well as the ICA. Here you can see the optic nerve and carotid artery. The tumor around these cerebrovascular structures was also removed and the affected dura was heavily curated and coagulated to minimize the risk of future tumor recurrence. Post operative MRI demonstrated complete removal of the mass without any complicating features. And this patient made an excellent recovery, thank you.

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