December 17, 2015
Resection of large tuberculum sella meningioma is more amendable to the transcranial versus endoscopic approach. Let's review the details here. This is a 52 year old female, who presented with significant progressive visual dysfunction with her left eye severely affected to the point of almost blindness. Her MRI demonstrated a relatively homogeneously enhancing mass centered over the area of the tuberculum sella, with a dural tail characteristic of a Tuberculum Sella Menangioma. You can see that the pituitary stalk is mobilized posteriorly, as well as the pituitary gland is mobilized inferiorly and posteriorly. The Coronal images are quite important in managing these cases. Number one, you can see the tumor is significantly in casing bilateral collateral arteries. Very importantly, the tumor it's lateral border extends beyond the lateral border of the optic nerve bilaterally. This special configuration and extensive lateral reach of the tumor, obvious the use of an endoscopic approach as the reach of the endoscopic approach or the optic nerve is quite limited. And the use of the transnasal approach in this case, most likely will lead to a subtotal resection. Importantly, you can see that the tumor has invaded both optic canals and more specifically, along the medial aspect of each canal and the Optic Nerves are pushed laterally. This is the typical location for the Tuberculum Sella Meningiomas to invade the optic canal and compromise vision by compression on the optic nerves. Therefore, both optic canals have to be thoroughly explored in this case, because of the significant compromise of the left optic nerve and left frontotemporal craniotomy was deemed most appropriate for handling this mess. For incompletion of the pterional craniotomy, the lateral aspect of the pterional was drilled away and the roof of the orbit was also drilled flat to improve our subfrontal operative trajectory. The edge of the frontal craniotomy was also flushed ,with the roof of the orbit. I believe this maneuver, I've always the use of an orbital zygomatic craniotomy. The medial aspect of the lesser sphenoid wing was also drilled thoroughly. Although an ex total craniectomy would be quite a reasonable next maneuver. I proceeded with exploring the nerve intradurally first, the dura was open in a standard curve, linear fashion. The retention sutures were placed as close to the edge of the craniotomy as possible to mobilize the dura away from my working zone. I use thin patties to mobilize the brain. Next, the anterior aspect of the Sylvian fissure is dissected. The arachnoid bands were quite thick in this area. Standard sharp dissection techniques are used, to open the anterior limb of the fissure and drain additional CSF. High magnification using the mouthpiece, allows efficient use of the microscope to keep all these structures in focus, while operating under a well illuminated opera field. These are some of the basic principles of Sylvian fissure dissection that are quite standard. These techniques are also reviewed here. Now, the arachnoid bands over the optic nerve are being dissected. Here's some of the MCA branches within the fissure, generous dissection ,the arachnoid bands reduces the need of fixed retraction, so that gravity can mobilize the brain away from our operative sound. Here is the third nerve, not affected by the tumor and that's the carotid artery, that's the optic nerve. The first maneuver involves devascularization of the tumor along the midline anterior skull base. It is important to stay within the midline in order to avoid injury to the contralateral optic nerve, here is moving posteriorly across the tuberculum, where the tumor has been devascularized. This early devascularization significantly facilitates the later stages of debulking and dissection without significant blood loss. You can see the nerve is quite affected by the tumor. And there's no clear planes between the two at this stage of the operation. I continue to stay along the midline and primarily focus on devascularizing the tumor. It is better or prefer to approach the lesion via the optic nerve that is more effected as the Ipsilateral nerve often is more manipulated than the contralateral one through the cross transcranial approach. So now some of the superior polar of the tumor is being quite coagulated and shrunken and debulked. This maneuver is requiring an expectation of mobilization of the tumor underneath the optic nerve. Piecemeal removal is achieved via pituitary rongeurs. You can see the contralateral frontal lobe at the tip of the arrow. The optic nerve should be in this location contralaterally. I stay close to the midline and avoid any aggressive coagulation blindly on the contralateral side of the tumor, to prevent inadvertent thermal injury to the nerve, tumor is quite fibrous. I continue to debulk the tumor using various instruments. Here is working around the area of the contralateral optic nerve, which should be just about here. I respect the arachnoid memories as much as possible. Here you can see a peak view of the optic nerve, contralaterally entering its canal. There are two ways to identify the nerve, either anteriorly or around the chiasma during dissection of the posterior pole of the tumor. Now that the contralateral optic nerve is more localized, I can be more aggressive. Here's the nerve in sheath by its arachnoid membrane. The tumor is pulled away from the nerve without coagulation. Now I focus on the Ipsilateral nerve. The falciform ligament is opened and a plan between the nerve and the tumor is developed. Here you can see that the nerve is affected on its both sides by the tumor, both along the medial and lateral aspect of the optic canal, still carotid artery. I minimize the manipulation of the nerve and continue to debulk as much of the tumor as possible while preserving the important perforating vessels. The carotid artery is more amenable to mobilization than the optic nerve already affected by the tumor. And the key factor is debulking the tumor, so the tumor can be mobilized away from the nerve rather than vice-versa Here's the tumor interface with a carotid artery, which can be readily developed. This appears to be the pituitary stalk that is adherent to the inferior and posterior pole of the tumor. Just medial of the V collateral artery, further debulking is necessary. Sharpy section is the best resection to mobilize the tumor capsule away from the neurovascular structures as much as possible. And this is the contralateral optic nerve. Is superior pole of the tumor is adequately dissected. I continue to debulk the tumor piecemeal, away from the contralateral optic nerve. Here is a better view of the contralateral optic nerve, which is quite effected and displaced by the tumor. Since this is the only good eye of the patient, I continue to ensure the safety of the nerve. As you can see, it's quite effective to debulk and mobilize the tumor medial to the nerve rather than lateral to it. The working angles are much more effective, when you approach Tuberculum Sella Meningiomas medial to the nerve rather than lateral to the nerve, therefore the contralateral optic nerve is often relieved of its mass effect more easily and effectively the the ipsilateral one. Now the arachnoid planes between the tumor and the ipsilateral optic nerve are developed, short dissection of the arachnoid bands between the nerve and the tumor, provides us with the roadmap to dissect the tumor and assures the patient that tumor dissection is possible. I mobilized the tumor as much as possible and leave the optic nerve unaffected. Here are some of the perforating vessels from the posterior communicating artery and anterior coronal artery, just posterior to the carotid wall. As you can see, I move from one spot to the other and debulk the tumor in a circumferential fashion, rather than focusing just in one area. Now I'm working along the medial optic frame and contralaterally to remove the tumor. You can see I'm pulling out the tumor from the contralateral optic foramen. That is a very important maneuver to assure decompression and improvement of the vision on the contralateral side. Now that there is some working space between the nerve and tumor, I continues coagulation to shrink the tumor away. Here's additional tumor devascularization along the tuberculum. The contralateral optic nerve looks quite decompressed at this point. The contralateral carotid artery also looks free of tumor. Most of the work on the contralateral side is completed first. Here's the contralateral optic framing, which is free of tumor. Now I continue to mobilize tumor away from the ipsilateral optic nerve. Here is the chiasma, much effected and attenuated by the tumor, here you can see the tumor has been mobilized away from the chiasma, further debulking will be necessary before additional manipulation is performed. At this time, the contralateral optic nerve and its junction with a chiasma is not clear. Ipsilateral optic nerve looks relatively free. Again, debulking of the tumor is necessary before aggressive manipulation is pursued. Here's the first step of the debulking. The ultrasonic aspirator is quite effective in these narrow spaces to remove the tumor without significant traction on the neurovascular structures including the optic nerves. The contralateral optic nerve is now more in view and its junction with the chiasma. The tumor is quite adherent at dislocation, sharp resection is preferred as much as possible. If the tumor is too adherent, small piece of tumor may be left on the nerve. Here's the contralateral posterior aspect of the optic nerve, that's being dissected away from the tumor. I'm using sharp dissection as much as possible. Further tumor debulking is in order, again you can see the tumor is being mobilized away from the nerve rather than vice-versa. And here's the contralateral optic nerve joining the chiasma. Further tumor debulking will allow me to look around the walls of the tumor to carry on with additional circumferential dissection of the tumor away from the optic apparatus. Here's additional plane of dissection against the contralateral optic nerve. Now you continue dissecting along the pituitary stalk just between the optic nerve and carotid artery or in the optical carotid triangle. You can see their contralateral neurovascular structures. The tumor is quite adherent to the pituitary stalk. Most often dissection plan can be developed with patience. Angle dissectors are effective for working around the corners without retracting the optic nerve. Some bleeding was encountered in carefully controlled, most likely at the base of the tumor along the anterior aspect of the Sella. Here's the pituitary stalk or relatively good dissection plane is developed. The base of the tumor within the Sella is also disconnected. Here's the superior part of the pituitary gland, I continue work on mobilizing the tumor out of the Sella and dissecting it from the superior aspect of the pituitary stalk located just about here. This dissection is readily performed and here's pulling out the tumor out of the sella. This is the largest piece of the tumor that's being removed outside of the Sella. Is the pituitary stalk, Small amount of tumor over the interior Sella is also removed using angle dissectors and curettes. Can see the final result with adequate decompression of the optic nerves on both sides, both optic canals were inspected carefully to assure complete removal of the tumor, using angle dissectors and removing tumor from the medial aspect of the ipsilateral optic nerve, further inspection reveals no other compressive lesion. Here's the status of the brain at the end of the operation. And you can see on the postoperative MRI that a relatively adequate gross total resection of the tumor was achieved, including the portion of the tumor within the Sella, without any complicating features. This patient had definitive improvement in a right vision. However, the left eye has remained nonfunctional. Thank you.
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