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Medial Tentorial Meningioma: Supracerebellar Transtentorial Approach

February 13, 2016

Transcript

I would like to share this very interesting case of a large medial tentorial meningioma that are resected via the supracerebellar transtentorial approach. I do believe this is a creative and innovative way to remove medial tentorial meningiomas. This is a 42-year-old male, who presented with minimal visual dysfunction related to this tentorial meningioma, which is really based very medially along the falcotentorial junction. This tumor can be readily approached via a subtemporal approach from the lateral side. However, their retraction on a temporal lobe will be significant and the optic radiations and the vein of Labbé would be at risk. I have approached these tumors via the supracerebellar transtentorial route, which offers early access to the base of the tumor, in it's early devascularization. However, this operative quarter is quite long and narrow and can be technically quite challenging. I do believe that avoiding manipulation of this supratentorial contents adds significant safety to the operation at the risk of increasing the technical difficulty of the surgery. Let's go ahead and find out about the tenants of this procedure. The patient is placed in a lateral position, a lumbar drain is used. You can see the incision, the location of the transverse sinus. One third of the incision is above the sinus and two-third below the dural sinus. You can see the location of the mastoid groove, incision is between the mastoid groove and the inion. Following completion of the incision, a craniotomy is exposed. You can see the location of the transverse sinus, to draw above the sinus is also exposed, and incision within the dura in the curvilinear fashion is demonstrated. One of the paramedian bridge remains is coagulated and cut. Two sutures are placed along the posterior aspect of the tentorium to mobilize and elevate the transverse sinus gently expanding the operative corridor. You can see the tentorium. You can see the vascularity at the base of the tumor guided by navigation. I can go ahead and devascularize the tumor early by cutting the tentorium around the base of the tumor and coagulating the edges of the tentorium during performance of the incision. This is the posterior aspect of the tentorial sectioning, just anterior to the transverse sinus. I have intruded the tumor now, and I'm devascularizing its space. You can see the operative corridor is narrow. The cerebellum is quite full, despite aggressive lumbar CNS CSF drainage. I continued to debox on the tumor to create additional space. Tentorial incision is extended more medially, obvious the midline and the straight sinuses preserved, the hook elevates the dura, while the scissors continue to section the tentorium. You can see the base of the tumor peaking through our transtentorial corridor. Here's the tumor. The tentorium is pulled into the infertentorial space. I continue now to section the tentorium parallel to this straight sinus and just lateral to it. Navigation is quite useful. Coagulation is used generously to control bleeding from the tentorium, that is hypervascular. This is specially challenging as the tumor has increased the vascularity of the tentorium. Additional working space is required, so I will continue to remove and debulk the tumor at its base. The laborious part of the operation is now in order as the tumor is being removed piecemeal into this area. As you can see, the corridor is very narrow. Pituitary are used to debulk the tumor as much as possible. I'll continue to reach the anterior aspect of the tumor and debulk it as much as possible. You can see the long operative corridor, the tentorium is being elevated temporarily using a fixed retractor blade. Here's the medial aspect of the tumor over the tentorium that is being removed. The falcotentorial junction is just about here. Here's a more demagnified view of the operative corridor. Here's the basal occipital lobe. This finding emphasizes the fact that the tumor has been adequately removed along its superior pole. The affected tentorium is again, pushed inferiorally. The lateral extent of the tumor is now evacuated until normal poster basal occipital lobe is encountered. The petrous ridge is located here. I continue to follow the route of the ridge while the tumor is being removed over the tentorium. The operative blind spot is just over the tentorium and laterally. So this incision should be performed as lateral and as close to the petrous ridge as possible. I attempt to remove the largest segment of the affected tentorium. It is moving more anteriorly. I'm specially careful to protect the fourth nerve at the level of their tentorial incisura. You can see the very limited operative corridor and limited visualization of the structures. Here you can see the edge of the incisura. The cuts are really small at this point to avoid inadvertent injury to the fourth nerve. Here you can see the incisura is completely disconnected. I continue to pull the effected tentorium into my resection cavity. All the emphasized vessels are carefully protected. Now more medially, the cut along the tentorium is advanced. Endoscopy plays an important role as you will see in a moment to look around the corners of this very limited operative space. Here's more of the tumor that is now more gelatinous as it's been completely devascularized, it's been removed using the suction device. Any posterior cerebral artery branches, as you can see here are very carefully protected to avoid occipital lobe ischemia. Here's again, the affected part of the tentorium that is pulled into our resection cavity after its medial attachment is disconnected. Some of this smaller arachnoid bands are disconnected. And pulmonary vision is used to clear the operative field. Here's the part of the tentorium that was affected by the tumor that is removed, further inspection reveals no obvious tumor. I have a very careful inspection of the operative borders are especially mandatory in this case, as you consider is potentially some small amount of residual tumor laterally. Here's the endoscope that is brought into the operative field. Now I look more medially and you can see the tumor that is being removed along the falcotentorial junction. Here, you can see the tumor that is being evacuated just along the straight sinus. Here you can see that tumor that's being brought into this suction. Now that the tumor is removed as much as possible in that area, I'll inspect the entire resection cavity. Here, you can see the falcotentorial junction, No obvious residual tumor is seen. I'm relatively satisfied in other areas. Post-operative MRI demonstrates relative growth store reception of the mass. This patient benefited from improvement in his vision and did not have any other untoward effect from his operation. Thank you.

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