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CP Angle or Tentorial Meningioma

February 10, 2016


Here is a resection of a CP angle or tentorial meningioma. This is a 55-year-old male, who presented with progressive imbalance. MRI evaluation revealed a meningioma centered and based underneath the tentorium, growing into the CP angle, leading to brainstem compression. He subsequently underwent a left-sided retromastoid craniotomy. Sigmoid sinus. Transverse sinus. The dura over the petrous bone. Arachnoid bands were widely opened, to release the cranial nerves. The superior petrosal sinus was coagulated and cut, and the tumor was devascularized at its base. This is an important initial maneuver, so that blood loss is minimized, and the tumor can be efficiently debulked. Here's the seven and eighth cranial nerves. The bulk of the tumor. Petrotentorial junction. Can see the tumor is being further disconnected at its base. The fifth cranial nerve is identified. Here's going all the way across the base of the tumor. The fourth nerve has to be protected at the level of the incisura. You can see that the more proximal segments of the trigeminal nerve are quite adherent to the inferior pole of the tumor. I like this maneuver, where I use the fine forceps to grab the arachnoid bands, encasing the nerve and mobilizing the nerve away from the tumor mass. This maneuver minimizes direct manipulation of the nerve, and is most atraumatic. Further demonstration of this technique. Now that the trigeminal nerve is mobilized, the tumor capsule can be further isolated. Before the bulk of the tumor is removed, it is further debulked, due to its large size. The posterior fossa portion of the tumor, which was the dominant part of the tumor, is removed. Next, I'm going to create a transtentorial, or a tentorial window, to remove any part of the tentorium affected by the tumor. Here's the petrous ridge, or the petrotentorial junction. You can see the tumor infiltrating that part of the tentorium. Small piece of the tumor that is invading the petrous apex may have to be left behind to protect the trochlear nerve. Here's a de-magnified view of the operative corridor. And postoperative MRI demonstrated gross total removal of the mass, and this patient made an excellent recovery. Thank you.

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