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Olfactory Groove Meningioma: Supraorbital Craniotomy

December 18, 2015

Transcript

Let's discuss resection of an olfactory groove meningioma, via the supraorbital craniotomy through a Soutar or modified bicoronal skin incision. This is a 55-year old female who presented with headache and personality change. And on MRI was diagnosed with a classic olfactory groove meningioma with a dural tail, with significant evidence of bifrontal edema. Endoscopic transnasal or supraorbital craniotomies through either eyebrow or modified bicoronal incision are all appropriate approaches. However, in this case, I decided on a supraorbital craniotomy. This is one of the early cases in my series. You can see the Soutar or partially modified bicoronal incision. The patient's head is turned slightly toward the left side, approximately only 10-20 degrees. The temporalis muscles reflected laterally. The keyhole is exposed. Next, the keyhole is completed. The orbital rim was not removed in this case. The eyebrow incision significantly limits the vertical height of the craniotomy, however, this more extensive Soutar incision, allows a... Taller craniotomy, therefore, facilitating mobilization of the frontal lobe and removal of the tumor through its generous exposure. I use the Penfield dissector to feel and palpate the level of the roof of the orbit. The initial osteotomy is a standard supraorbital craniotomy. I usually try to use navigation to avoid entering the frontal sinus. However, this should not limit the amount of exposure that can be necessary for removal of the tumor via restricted craniotomy. The initial osteotomy goes all the way to the level of the orbital roof, where the drill's progress is... Stopped due to the orbital roof. Next, the drill is turned 180 degrees around itself. As you can see, and the heel of the drill is removed. You can see the roof of the orbit. The second cut is through the initial burr hole, because I can stay as close to the... level of the orbital roof as possible. After the bone flap is elevated, the overhang along the frontal edge of the craniotomy is generously drilled away. So, there is no obstruction for the operative corridor, toward the the sub frontal area. You can see the roof of the orbit. Everything is flush with the roof and at the same level, the door is open and currently in fashion. As I mentioned before, this is one of the earlier cases in my series, and unfortunately the lumbar drain was not used. You can see the evidence of the brain swelling. The lumbar drain would have significantly assisted with brain decompression, allowing early exposure and devascularization of the tumor without aggressive frontal lobe retraction. The initial step for tumor removal involves aggressive devascularization of the tumor from the dura over the midline and olfactory groove. I continue to devascularize the tumor and debulk its interior pole, so crista galli can be exposed and partially removed using Kerrison rongeurs, so I can reach the contralateral aspect of the tumor, and devascularize this contralateral portion. This tumor remained quite vascular on midline, which is expected in these tumor types. I persisted with devascularization along the base of the tumor until hemostasis was secured. Additional tumor mobilization expose crista galli. Here's the more lateral part of the tumor that is being mobilized. This residual piece of the tumor will be removed using various curettes at the end of the procedure. And the bone that is affected will also be drilled away. The tumor was also mobilized away from the base of the frontal lobe. Further debulking was necessary to further expose crista galli. Here, you can see crista galli. A contralateral portion of the tumor across midline is not readily reachable. Additional tumor removal was necessary. Now, crista galli is more visible. Let's go ahead and use Kerrison rongeurs to remove this part. The more part of the crista galli, to expose to contralateral pull of the tumor. You can now appreciate a more contralateral component of the lesion across crista galli. Then I'm going to devascularize. The residual tumor along the dura is drilled away and the affected bone is also removed using drilling. The postoperative MRI demonstrates gross total removal of the tumor. This patient recovered from surgery without any untoward side effect. Thank you.

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