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Optic Foramen Meningioma

April 29, 2016

Transcript

Here's a video describing the technical nuances for resection of an optic foramen meningioma. This is a 31 year old female, who presented with right-sided visual field cut. MRI evaluation revealed an optic foramen meningioma on the right side, infiltrating the frame and, and leading to visual decline. You can see the amount of tumor that is essentially compression of the nerve. The tumors infiltrating the medial portion of the optic foramen. This pattern of tumor invasion is quite typical, in terms of pushing the nerve from the medial to lateral and invading the potential space along the medial portion of the canal. Patient underwent a right-sided frontal temporal craniotomy. Next and extradural clinoidectomy was completed, so that the nerve is thoroughly decompressed before intercranial and intradermal manipulation is undertaken. The clinoid was rather hypertrophied in this case, you can see that dura covering the nerve. Very generous 270 degree decompression of the nerve is mandatory in this case. So the tumor can be removed around the nerve. So I spent significant amount of time decompressing the nerve circumferentially and extending the decompression more anteriorly than a usual extradural clinoidectomy. The point is thinned down and then curates are used to remove the last remaining thin shell of bone. Ample amount irrigation is used during the process to avoid any thermal injury to the nerve. Here's a more lateral part of the nerve that is being decompressed. Fixed retraction is not used. You can see the dynamic detraction is quite adequate in this case. As the foramen is decompressed and unroofed, Kerrison Ronguers may be employed. You can see the nerve very generously decompressed and the dura of the subfrontal area is also apparent. Next, the dura is opened in a curvilinear fashion. Minimal amount of dural opening is necessary in this case, Dura is mobilized along its root. Here's our subfrontal operative trajectory, toward the nerve and the optical carotid cisterns. The contour of this finagled wing is followed until the nerve is encountered. Here's the tumor, readily apparent. Here's the nerve, just lateral to the tumor. Again, this configuration is quite typical for optic foramen meningiomas. The anterior limb of the sylvian fissure is dissected, so that the frontal lobe can be mobilized. The acom knife is used to untether all the arachnoid bands between the subfrontal area and the nerve. Here's the lateral to the carotid artery, where the arachnoid bands are opened and additional amount of CSF is released. The falciform ligament is generously transected so that the nerve is thoroughly decompressed, as early as possible. Here's part of the tumor that is being debulked. Angled instruments are utilized to deliver the tumor into our resection cavity. Please pay attention to this maneuver, where the tumor is mobilized away from the nerve, rather than vice-a-versa. Debulking continues. Perforating vessels are carefully protected. You can see a view of the contralateral optic nerve just behind this piece of the tumor. Again, I continue to deliver the tumor using angle instruments. Minimal manipulation of the nerve is conducted. Now I'm working within the foramen, and in the medial potential space within the foramen where the tumor often invades. Now reaching into the foramen to remove additional tumor. Perforating vessels should be, searched for and protected. You can see this perforating vessel toward the chiasum, is being untethered. Here's another perforating vessel. Epinephrine gel foam is used, to relieve the vasospasm within these tiny arteries. Protection of these perforating vessels is instrumental in avoiding post operative visual decline. Sharp dissection is ideal. In this case, the small perforator did not appear to lead to the chiasum and was sacrificed. Inspection of the foramen using a right angled blunt hook reveals no evidence of tumor and micro mirror also reveals complete decompression on the nerve and no evidence of residual compressive mass. The dura around the tumor base are coagulated to decrease the risk of future tumor recurrence. The contralateral optic nerve is also inspected to make sure the nerve is not affected. Here's the contralateral optic nerve. epinepherine soaked gel foam is used intermittently to relieve the vasospasm on the regional vessels. Here's further inspection of the contralateral side. You can see the contrad or nerve is unaffected by the tumor. Any small piece of the tumor that could be heading toward the contralateral nerve on the tubercular dura is also resected. The base of the tumors is curated away. Ample amount irrigation is used and the post operative MRI in this case revealed, gross total removal of the mass. This patient's vision significantly improved after the surgery. And you can see that their foramen is thoroughly decompressed and there is no residual tumor within the foramen. Thank you.

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