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Sphenoorbital Meningiomas

December 17, 2015

Transcript

Resection of sphenoorbital meningiomas involves some degree of anterior skull base osteotomy and reconstruction, and requires strategic planning. This is a 52-year-old female who presented with right-sided proptosis and on MRI examination, more specifically a T1 axial image. With contrast, you can see evidence of a meningioma, involving both the intradural and extradural spaces, as was invasion of intraorbital contents, and most likely periorbital. A CT scan evaluates the extent of our prostosis and bony involvement. You can see the roof of the orbit and its more lateral part, as well as the area of the pterion, and a lesser sphenoid all the way to the level of the clinoid process are all affected. And you can see that again, the inferior aspect of the lateral part of the the orbit and also the inferior aspect of the pterion are affected, therefore an extensive osteotomy and orbitozygomatic craniotomy are necessary for gross total resection of this tumor. A lumbar drain was used at the beginning of the procedure. Also during the preoperative period, a custom cranial implant was prepared to cover the defect expected after tumor removal. Here's the placement of the lumbar drain to decompress the dural sac and facilitate osteotomy without placing the dural or intradural contents at risk. Here's the positioning of the head and minimal amount of head turn. Standard pterional incision is quite adequate. A piece of pericranium was harvested to close that dural defect at the end of the procedure. The temporalis muscle scalp were reflected in separate layers using the sub fascial technique. The area of the pterion affected by the tumor is evident. This area is drilled away until the soft bone is encountered, and relatively normal edges of the dura are identified. are used to remove the soft tumor. Here it is again, some curetting removing the softer part of the bone affected by the tumor, this is the relatively normal edges of the dura. It's the roof of the orbit. Again, this roof is partly affected. Now that periorbital is dissected away from the orbital rim, an orbital psychomatic craniotomy is completed. A B One bit is used to cut across the orbital rim, and part of the anterior orbital roof, and other osteotomies completed along the frontal process of zygoma. These bony cuts complete the orbital zygomatic or the modified supraorbital osteotomy. The bone flap is elevated. It's important not to use aggressive force, as the high prostatic orbital roof can transmit the pressure to the optic foramen and the bone over it, leading to the fracture and compression of the optic nerve as it enters its foramen. So here's the area of the pterion and the lesser sphenoid wing affected by the tumor. I'm going to continue to remove the tumor in this area. This is the cranial custom implant. Here's the periorbital, here's the lateral wall of the orbit. That's being again affected by the tumor and is resected. Here's the area of the clinoid process and a medial sphenoid wing. I remove as much of the soft bone until hard bone and normal bone is encountered. After removing the lesser wing and reaching the clinoid process, I continue to work both on the lateral wall of the orbit and the clinoid process and skeletonized the posterior aspect of the orbit, here is the supraorbital fissure. Here you can see the fissure, it's being skeletonized on both sides. Here's the residual clinoid. Here's again, additional work over the area of the clinoid process until the roof of the optic nerve is removed. Again, additional affected bone is removed until hard bone is encountered along the floor of the temporal fossa. Here's the dura over the optic nerve before the clinoid the process is removed. Here's coring out inside the clinoid process and removing the roof of the optic nerve immediately. Again, the bone is relatively soft. Here's complete removal of the clinoid process. Here's the final product, you can see the lateral anterior skull base is skeletonized, periorbital fissure of the optic nerve. The posterior wall of the orbit, the periorbita. Part of the tumor has affected the superior orbital fissure, therefore preventing a gross total resection of the tumor-infiltrated dura. You can see the drilling continued until hard, normal bone was encountered. This is additional relatively normal anatomy of the lateral anterior skull base that is being reviewed, the optic nerve. Now the portion of the periorbita infiltrated by the tumor is being removed and is being separated from the orbital fat. Obviously the extent of resection has to stop at the level of the superior orbital fissure. This part has been coagulated to achieve as much tumor control as possible. Now that the interorbital portion of the tumor is resected, the affected dura is cut and the intradural portion of the tumor is removed in standard fashion. All the arachnoid membranes are respected as much as possible. Here's the middle meningeal artery feeding the tumor. Extent of tumor resection again at this juncture also reaches the superior orbital fissure. Here's the part of this soft frontal dura that is being resected up to the level of a relatively normal-appearing dura. The edges of dura are coagulated for further tumor control. Here's the area of the square orbital fissure. The tumor had invaded part of the pia. Now the piece of pericranium, a free flap piece of pericranium is used to reconstruct the dural defect. In this case, the plan had to be cut, because the lateral calvarial portion of the implant was not a good fit. The orbital rim was reconstructed using the implant and the rest of the calvarial was reconstructed using a piece of titanium mesh. The subtemporal defect was left alone, as this part will be covered by the muscle. Here's a postoperative MRI, demonstrates gross total resection of the tumor without any complicating features. Their proptosis anticipation was completely corrected. Thank you.

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