January 06, 2016
Although cystic brainstem cerebellar hemangioblastomas are relatively easy to resect, their solid components are quite challenging and provide daunting technical hurdles in their resection. More specifically, solid hemangioblastomas contain cavernous components. These caverns are quite resistant to bipolar coagulation as they lack bonafide walls that are not collapsible. Therefore intraoperative hemostasis can be quite challenging. Let's review an especially challenging case. This is a 52 year old male with progressive stroke gait dysfunction, and he had previously undergone an unsuccessful attempt at resection of his tumor years prior. The MRI scan demonstrates a relatively solid mass at the lower portion of the cerebellopontine angle cisterns also compressing the medulla. The angiogram demonstrated large feeding vessels from the ascending pharyngeal artery in terms of the extra cranial vasculature feeding the malformation, as well as the pial collaterals from the ICA and PICA branches. You can see this lesion is quite vascular and essentially acts as an extra axial arteriovenous malformation. The patient underwent the procedure in the lateral position, brainstem auditory evoked responses were monitored, the previous incision is demonstrated, and we had to fashion our incision around the previous incision by extending it inferiorly, therefore reflecting the flap out of our working zone. The initial evaluation after we move the bone involved using the FLOW 800, which is an ICG-based vascular study, demonstrating the time-dependent feeding vessels into the malformation or the hemangioblastoma. As you can see, this is the hemangioblastoma. This is the, here, the petrous bone. There would be foramen magnum here, and obviously most of the feeding vessels, which is the hot spot or the rest spot are from the inferior lateral aspect of the lesion facing the lower aspect of the petrous bone around the area of the jugular foramen. Here's the exposure. You can see that the cisterna magna was punctured. Ample amount of CSF was released. The gliotic cerebellum over the tumor was resected. Here is the lesion as the cap of the cerebellum was removed to provide working space over the lesion. Initially, Cottonoid patties were used to wipe the brain away from the malformation or the hemangioblastoma. I attempted to devascularize the tumor from its origin at the level of the jugular foramen, you can see the highly vascular nature of this lesion. Unfortunately, many of the portion of the mass are not amenable to traditional bipolar coagulation. I dissect the superior pole of the tumor and attempted to identify the neurovascular structures including the cranial nerves early. Although this portion of the operation was relatively straightforward, any attempt at devascularizing the tumor from its pedicle over the area of the petrous bone and jugular foramen was faced with significant amount of bleeding that was very difficult to control. Here are some of the cranial nerves that are being identified early, most likely they're branches of the lower cranial nerves. Hemangioblastoma is quite tense and associated with a high turgor due to the amount of blood flowing within the mass. The initial resection around the superior lateral portion of the tumor is relatively straightforward again. The cranial nerves are being protected and shouldn't be dissected. You can see these large feeding vessels and draining veins, their control is almost impossible due to their lack of coagulable walls. I used different methods of hemostasis, including Gelfoam powder soaked in thrombin and Floseal. Despite these efforts, you can see the bleeding continues. It's quite torrential. Patience is a virtue especially under these circumstances. We continue to lose a serious volume of blood, at the same time, remained persistent and devascularized the lesion from its pedicle. And you can see the exuberant bleeding from the area of jugular foramen and its more inferior aspects. There is no identifiable bleeding source. Using the non-stick bipolars was especially important technique in order to control the bleeding. Again, using Gelfoam powder soaked in thrombin to pack the areas of the bleeding, and seal the defect in the caverns of the lesion seemed most appropriate and effective in this case. We continued to remain specially careful about the amount of blood that we were losing. And after about one and a half liter of blood loss, felt that staging the procedure is most likely the safest strategy. Here, you can see some of the lower portion of the tumor being dissected off of medulla. The mass remains quite tense, does not appear to be significantly devascularized. Further attempts at its devascularization led to additional amount of blood loss. Even though this lesion was somewhat embolized from some of the larger pial feeders, preoperatively, you can see it continues to have many other feeders most likely from other pial collaterals. Therefore this procedure was abandoned due to, again, extensive amount of blood loss, and the procedure was staged. But 10 days later, additional embolization of the ascending pharyngeal artery was completed. This embolization procedure was complicated with some bleeding within to the pons in the cerebellum. Upon our return, you can see the lesion is much more manageable. I had to decompress the mass somehow in order to be able to mobilize it away from the brainstem. Ultrasonic aspirators were used. This is a live portion of the mass that was entered and I continue to remain persistent, and use bipolar coagulation as much as possible in addition to Gelfoam packing to control the bleeding. Ultimately, I was able to reach the capsule of the tumor interfacing the brainstem. The arachnoid bands between the mass and the brainstem were carefully protected and sharply dissected to avoid any pial invasion into the parenchyma of the brainstem. Again, piecemeal decompression of the mass was necessary to create additional space for mobilization of the mass away from the brainstem rather than vice-versa. A more devascularized portion of the tumor appears as such. Again, you can see the cavernous texture of the mass. There is no real obvious vessels within the mass but rather caverns that are filled with blood. Here's the vertebral artery, C1 nerve branches or rootlets. Here's the pia of the medulla. Here, you can see the PICA that is being carefully protected and a dissection is being carried along the arachnoid bands. Here you can see the vessel somewhat engulfed by the malformation. Some of the veins on the surface of the brainstem can be quite challenging to control, however, they have to be isolated, coagulated, and dissected away from the capsule. Here's a capsule of the malformation being dissected, again, from the brainstem. The magnified view provides the viewer with some orientation of where we are. Here again, is the capsule being mobilized from the brainstem. Here is the more necrotic part of the tumor laterally, the brainstem is here. Some of the nerve roots around the vertebral artery. Here's the arachnoid along the anterior aspect of the capsule. Here's the bleeding from the embolization procedure that is being evacuated. This part of the clot is mostly extra-axial. Here's the postoperative MRI which demonstrates a radical, near total resection of the malformation or the hemangioblastoma. The small amount of a capsule that was very adherent to the medulla was left alone to prevent any transgression of the pia in the region. Here's some more organized blood related to previous episode of hemorrhage, related to the embolization procedure. And here is a coronal view with contrast, which demonstrates a very thin sheet of tumor that was left behind, or the pial of the brainstem where the mass was very adherent to avoid any pial injury or violation of the perforators in this area. This patient suffered from significant amount of swallowing difficulty that required placement of a gastrostomy tube. His case also worsened after these series of procedures. However, he has continued to improve during his six months evaluation. Again, this video demonstrates the daunting challenges associated with treatment of solid hemangioblastomas, their cavernous character, difficulties in control of the bleeding, and also the importance of staging of the procedure, if necessary, to avoid excessive blood loss. Patience and control of the bleeding using different hemostatic methods is quite important. And if a small amount of tumor has to be left behind over the pia to protect the neurovascular structures, such small amount of tumor should be left alone to protect neurological function. Thank you.
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