Dominant Insular Glioma: Strategies for Tumor Removal
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Let's review another example for resection of dominant insular low-grade gliomas. This is a more challenging case since this is a recurrent tumor. This is a 32 year old female, who previously underwent a subtotal resection of her left insular glioma years ago, in an outside institution. She subsequently recurred, as you can see, in terms of her tumor, the mass is primarily located at the area of the insula, however, there is some extension of the tumor along the anterior temporal lobe. Therefore, this tumor is primarily an insular temporal low-grade glioma. My strategy in this case, involved removal of the portion of the superior temporal gyrus affected by the tumor. This resection would provide an expanded trajectory via the trans sylvian route, to remove the part of the tumor within the insula. An inferior to superior operative trajectory will be selected to remove the more superior pull of the tumor. Let's go ahead and review the operative events, in this case. She subsequently underwent a left frontotemporal craniotomy, the previous curvilinear incision was slightly extended. The drapings are also illustrated here. I mapped the inferior frontal gyrus, as well as the superior temporal gyrus. The reason behind this strategy is, the trans sylvian corridor may not be entirely adequate, for removal of large insular tumors. If I map the superior temporal gyrus, as well as the inferior funnel gyrus, I'll be able to perform Corticotomy safely within these cortices, in order to expand my operative corridor, and remove the superior or inferior poles of the tumor. In this case, the Sylvian fissure was first dissected, as you can see here, I'll go ahead and map the fairs. and the tongue area followed by the motor speech.
[Patient] Three, four, five six, seven, eight, nine, ten.
Here's motor speech. Go ahead and map the language.
[Patient] "We won a first place ribbon". "The man read a book".
That's... go ahead.
[Patient] "The boy played games on the computer".
Okay, you are reading okay. So in this case, the superior temporal gyrus did not appear to carry any function, at least the areas that were exposed within the operative field. I further skeletonized the MCA branches before proceeding with removal of the anterior superior temporal gyrus. You can see the previous area of resection cavity, some white scarred in the insula affected by the tumor. Here's part of the resection involving the superior temporal gyrus, providing additional space for removal of the insular portion of the tumor. Here are some of the MCA branches. Now I divert my attention toward the operative trajectory posterior to the MCA territories. The response of the tumor to the bipolar coagulation is different than the response of the normal white matter. This methodology and this difference can be quite effective in guiding the surgeon for aggressive removal of the tumor. You can see some of the MCA branches here, the M1, working underneath these branches to remove additional part of the rubbery grayish tumor, here are the M2 and M3 branches, here is M1. I continued to remove additional tumor while looking for lateral and straight arteries that define the most medial border of the resection. Next I create these working windows between M2 and M3 branches to access additional part of tumor. And you can see the tumor is relatively easily suck-able after it's coagulation. MCA branches have to be carefully protected and periodically bathed in a Pavrin using Papaverine soak-gel foam pledgets. Here, you can see the Potter resection getting close to the striatum. Another working window is created just more anteriorly again between the M2 and M3 branches here You can see two working windows and the third one more posteriorly, the part of the tumor hiding underneath the MCA branches is also removed. The most prominent blind spot is just underneath the frontal operculum. I continue to create additional working spaces here. Frequent inter operative neurological examinations are important for providing the surgeon with additional confidence in remaining aggressive in tumor resection. Here You can see I'm focusing on the tumor close to the internal capsule. I use thrombin soaked piece of cotton for hemostasis, gentle used and aggressive coagulation over the perforating vessels is avoided. Here you can see the lateral lenticular straight arteries, very nice demonstration of these vessels. Obviously any injury to these vessels can lead to hemiplegia or hemiparesis. here's a more de-magnified view of these important vessels. Again, one, two and three working channels. here is removal of the tumor close to the internal capsule or posteriorly. I use subcortical mapping to guide resection of the tumor in this area, Initial bathing of the vessels with Pavrin additional inspection reveals no obvious tumor neuro navigation can be at times confusing due to brain shift. Therefore surgical judgment and experience are quite important. As you can see here, their navigation is somewhat not reliable, Post-operative MRI in this case revealed adequate removal of the mass and this patient recovered from her surgery without any neurological deficit. Thank you.
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