December 10, 2015
Resection of giant recurrent cerebellar hemangiopericytomas can be quite challenging. This video describes the case of a 48 year old female with progressive history of imbalance as well as history of subtotal cerebellar hemangiopericytoma resection. Years earlier, she did not undergo radiotherapy after the initial index operation. Due to her progressive symptoms she underwent MRI evaluation, which revealed this very large hemangiopericytoma centered over the jugular foramen and the area of the entry into the foramen of the lower cranial nerves. Angiography revealed a relatively hypervascular tumor but no obvious pedicles to embolize. There is remarkable evidence of brain stem compression and therefore operative intervention, at her young age, was indicated. You can see that the tumor extends all the way to the posterior aspect of medulla oblongata. And this is gonna be the trickiest part of the operation, to dissect the tumor without injury to the surrounding structures. Obviously the hypervascularity of this tumor and its close association to the lower cranial nerves is important. The patient's otolaryngological preoperative evaluation demonstrated malfunction of the lower cranial nerves on the right side. Nonetheless, significant vascularity along the area of the jugular tubercle is expected. The previous linear incision was used. The dura was opened in a cruciate fashion as you can see. In the area of the gliosis the part of the cerebellum that was gliotic was removed over the capsule of the tumor to expose the posterior pole of the tumor. You can see that from the initial part of our dissection the tumor proved to be highly vascular. Here's the right cerebellar hemisphere around the tumor. I continued to remain persistent in the face of bleeding and coagulate the capsule of the tumor, knowing that additional bleeding and more torrential bleeding expected along the CP angle and the jugular tubercles. So here is a demagnified view of my initial dissection, to orient you to the initial findings, you can see the dura is reflected laterally. The tumor continues to bleed despite aggressive coagulation of the capsule and surrounding cerebellar gliotic margins. After the initial tumor removal and some degree of hemostasis, the tumor was debulked so the tumor can be mobilized away from the CP angle structures without undue pressure and traction on them. Upon coagulation of the capsule the inside of the tumor seems to be less vascular and more easy to handle. Here is the difficult part of the operation, where the tumor is being devascularized from the dura of the CP angle. The majority of bleeding is from the large venous channels connected to the dura. These venous channels can be quite difficult to coagulate because the walls are not amenable to bipolar coagulation and collapse. Gel foam powder soaked in thrombin with gentle tamponade was used to seal off some of these low pressure veins along the dura. However, this maneuver seems to be not very effective. You can see some of these large venous channels along the dura near the tumor capsule. Because of the lower cranial nerves, function was already compromised, aggressive coagulation deemed reasonable to achieve hemostasis knowing that there is additional risk to these nerves that could be even slightly functional despite our preoperative findings. Here's further debulking of the tumor so the capsule can be more aggressively mobilized away from the CP angle dura. Ultimately, I packed the area with pieces of gel foam soaked in thrombin and diverted my attention elsewhere, where the inferior pole of the tumor and its more medial borders were dissected away from the cerebellum and the posterior brain stem. Small pieces of Cottonoid were used to wipe the tumor away from the brain. Here you can see the nodule of the tumor that is encroaching upon the cerebellar hemisphere. The tumor does not own smooth margins, as expected, and it's nodular, complicating resection. The tumor is removed piecemeal. Here is the more critical part of the operation, where the posterior capsule of the tumor comes in close contact with the brain stem. Aggressive coagulation is avoided. This is part of this cerebellum still. We're gonna reach to the surface of the brain stem momentarily. The perforating vessels are carefully protected and identified before their sacrifice to make sure they are not en passage vessels. Here is further dissection along the capsule of the tumor. The tumor is fragmented into pieces so its removal can be facilitated. This debulking significantly improved the safety of the next stages of the operation by increasing the mobility of the tumor away from the brain stem rather than vice versa. Here is the area of the brain stem. You can see a piece of cotton is used and direct suction over the brain stem is avoided. The last pieces of the tumor proved to be more suckable. Here is additional piece that is being extracted. Here is the posterior aspect of the brain stem. Aggressive suction on this part of the tumor is avoided. A gross total resection was completed. The postoperative MRI demonstrates gross total resection of the mass all the way to the posterior aspect of the medulla without any complicating features. This patient did have some worsening of her swallowing right after surgery, but her swallowing returned to normal within three months post surgery. Thank you.
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