Acoustic Neuroma: Medium Size
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Let's talk about a resection of a medium sized acoustic neuroma via the retromastoid craniotomy. This is a 34 year old male, with decreased hearing and tinnitus. You can see the location of the tumor. Patient underwent a left sided retromastoid craniotomy, patient positioning and incision is marked. I used this form of incision earlier in my career. You can see the location of the transverse sinus, sigmoid sinus and an incision about three finger breadths, posterior to the pinna. Following completion of the left sided retromastoid craniotomy. Cerebellum was gently mobilized and the posterior capsule of the tumor was exposed. The capsule of the tumor was mapped to exclude the location of the facial nerve. Next the tumor was interred and generously debulked. Here's the trigeminal nerve, identified along the superior pole of the tumor capsule. The inferior pole of the tumor capsule was also stimulated and the lower cranial nerves were mobilized. Next the tumor was debulked further and the more medial pole of the tumor capsule rolled laterally. Sharp dissection was used. I continue to mobilize the tumor. The vestibular and cochlear nerves were disconnected, since the patient's preoperative hearing was relatively non-functional. Next, the tumor was mobilized further. I used fine forceps to gently mobilize the facial nerve away from the tumor capsule. This maneuver is very atraumatic. Obviously sharp dissection further mobilizes the tumor capsule. Next, I continue to mobilize the tumor capsule away from the facial nerve which is encased by its arachnoid bands. My manual dissection is quite effective. You can see the nerve is not directly manipulated. Again the facial nerve, gentle mobilization of the arachnoid bands without the direct manipulation of the facial nerve. The tumor is further debulked. The nerve is now covered and the portion of the tumor within the canal is resected. The canal is unroofed, skeletonized 270 degrees circumferentially, and the IC is entered and intracanalicular portion of the tumor is removed. Facial nerve is identified early. The affected part of the vestibular nerve is disconnected. Here is the facial nerve. Now the tumor is rolled medially. Again the facial nerve is located here. The tumor is most adherent at the level of the pores. The inner cells are waxed. Here is working around the area of the pores to remove the tumor. I work both laterally to medially and medially to laterally to roll the tumor. The nerve is radially stimulated at 0.5 milliamperes. Further debulking is conducted along the intercisternal portion of the tumor, to achieve a relatively normal postoperative facial function. I may leave a very tiny piece of tumor that is very adherent to the nerve at the level of the pores. Debulking continues in steps. This small part of the tumor appears adherent to the nerve, I debulk it further. Sharp dissection is used. Traction on the nerve is avoided. You can see a very thin sheet of the tumor left behind to avoid any injury to the nerve. The nerve is readily stimulated at 0.05 milliamps This patient's facial function was relatively normal after surgery. Three months postoperative MRI demonstrates a gross total resection of the mass, although a very tiny piece is left behind based off intraoperative findings. This very small piece of the tumor did not grow at five or tenure follow-up MRI examinations. Thank you.
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