Fourth Ventricular Ependymoma Adherent to the Floor
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Let's discuss some of the operative strategies for aggressive resection of fourth ventricle tumors, and in this case, an ependymoma adherent to the floor of the ventricle. This is a 44 year old male with dizziness, MRI evaluation revealed a fourth ventricular mass filling the ventricle and extruding through the foramen of Luschka. There was also some evidence of calcification associated with this tumor. Again, you can see the majority of the mass fills the foramen of Magendie as well. Based on the MRI, there is potentially significant adherence of the tumor to the dorsal portion of the brainstem. Patient underwent a suboccipital craniotomy in the lateral position and midline incision was used, so microsurgery can be conducted with a surgeon in the sitting position. Here's the suboccipital craniotomy creating a cervical junction. The dura is opened in a linear fashion. So it can be closed in a water tight fashion at the end of the procedure, very effectively. Here's the PICA that is exposed on the lateral aspect of the tumor. Here's the tonsil, the right tonsil. Again, the PICA, the arachnoid bands around the PICA. And here is the tumor. An important point to remember is that there is numerous PICA perforating vessels to the tumor and more specifically ependymomas in this area. These perforating vessels have to be carefully coagulated and cut and not avulsed so that the PICA is not under the risk of thrombosis. Here are some of the perforating vessels, can be appreciated here. Here's the tumor that has been isolated. First, I'll go ahead and find the inferior portal of the tumor and try to dissect the tumor from the dorsolateral aspect of the brain stem. You can see along the midline and the fourth ventricle, tumor is not very adherent and ultrasonic aspirator can actually remove the tumor relatively easily. However, the tumor is typically very adherent to the dorsolateral part of the brain stem and I have to leave a small sheet of the tumor behind to avoid any injury to the brain stem. Here's again, the floor of the fourth ventricle thinning down the sheet of the tumor that will be left behind. Aggressive manipulation of the normal neural structures that are adherent to the tumor in this location should be avoided. The residual tumor may be coagulated to minimize the risk of recurrence, and here's some tumor entering the foramen of Lushka that has been also removed. You can see that I'm just delivering the tumor into our resection cavity. I continue to use dynamic refraction to find the tumor going through the foramen of Lushka on the left side. Similar strategies used on the right side. You can see the lower cranial nerves through the foramen of Lushka and the tumor in this area is also evacuated. Here's the final result. You can see a very small sheet of the tumor bilaterally over the dorsolateral aspect of the brainstem. And here's the postoperative MRI. Relatively good resection of the tumor. Maybe a very small amount of residual tumor as expected in the dorsolateral aspect of the brain stem. Here is another sagittal view of our postoperative MRI, and this patient made an excellent recovery without any postoperative deficits. Thank you.
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