DATE OF OPERATION: MM/DD/YYYY
PREOPERATIVE DIAGNOSES: Left medium size acoustic neuroma and left severe to profound sensorineural hearing loss.
POSTOPERATIVE DIAGNOSES: Left medium size acoustic neuroma and left severe to profound sensorineural hearing loss.
OPERATIONS PERFORMED: Left translabyrinthine approach to acoustic neuroma, intradural resection of medium size acoustic neuroma, left medial facial nerve decompression, harvest of abdominal fat graft, microdissection, neuromonitoring with cranial nerve VII left side, and SSEPs.
SURGEON: John Doe, MD
ANESTHESIA: General.
ESTIMATED BLOOD LOSS: Approximately 150 mL.
COMPLICATIONS: None.
SPECIMEN: Acoustic neuroma. Frozen section preliminary diagnosis was consistent with a schwannoma.
DESCRIPTION OF OPERATION: The patient was taken to the operating room and placed supine on the operating table. After adequate general anesthesia had been obtained via endotracheal intubation, the patient was appropriately positioned and padded on the table. Attention was then turned to the right ear and right face. Facial nerve monitoring electrodes were placed along with placement of SSEPs. The facial nerve and neuro monitoring EMG system was then used throughout the procedure. Stimulation, dissecting instruments were used when dissecting around the facial nerve. Stimulation, dissecting instruments were used throughout the vast majority of the tumor resection portion of the procedure. A hair shave was performed.
The left postauricular region was then prepped and draped in the standard surgical fashion. Lidocaine 1% with 1:100,000 epinephrine was injected in the postauricular region. The operative microscope was used throughout the vast majority of the procedure, except for the skin incision and skin closures. The left side was confirmed as the operative side. A postauricular incision was then made in the C-shaped fashion. This was carried down to the level of the periosteum superiorly. Temporalis fascia was identified and harvested. A large T-shaped massive periosteal incision was made and periosteal flaps elevated.
Using cutting and diamond burs, a mastoidectomy was performed, canal wall up. The sigmoid was skeletonized along with the tegmen and the semicircular canals were identified. The incus was identified and removed. A limited facial recess approach was performed to get appropriate access into the middle ear space. Next, a labyrinthectomy was performed by removing the superior, inferior, and horizontal semicircular canals.
The vestibule was identified and widely exposed. Next, the mastoid segment of the facial nerve was skeletonized to fully expose the vestibule. The sigmoid sinus was then widely decompressed, extending into the rectosigmoid dura. This was carried down to the level of the jugular bulb. Superiorly, the dura of the temporal lobe was skeletonized and decompressed. The superior petrosal sinus was identified and preserved throughout the procedure. An overall wide bony decompression was performed of the posterior fossa dura and the middle fossa dura, extending medially. Next, the internal auditory canal was skeletonized and the superior and inferior vestibular nerves identified laterally in the internal auditory canal. The falciform crest was identified.
A medial facial nerve decompression was performed. Bone overlying the labyrinthine segment of the facial nerve was removed, decompressed. There were no traumatic potentials during this portion of the dissection. At this point, the internal auditory canal had been skeletonized in a 270 degree angle around it. All bone was removed from the posterior fossa dura and the middle fossa dura and over the internal auditory canal.
The wound was copiously irrigated and excellent hemostasis obtained. Intermittent use of the Kartush facial nerve dissecting instruments were used to map out the facial nerve and the tympanic mastoid labyrinthine and IC segments. There were noted to be excellent responses. The patient had been hyperventilated and mannitol had been given. The posterior fossa dura was noted to be pulsatile. The brain was noted to be well relaxed.
At this point, the tumor resection portion of the procedure was begun. A dural incision was made in the posterior fossa and the cerebellopontine angle space entered. CSF was decompressed from the cerebellopontine angle cistern. An acoustic neuroma, medium size, was then noted. It was noted to expand in the internal auditory canal and extend into the cerebellopontine angle. It was just abutting the cerebellum without causing any compression. There was no compressive effect on the brainstem. The stimulating dissecting instruments were used for the majority of this portion of the procedure.
The anterior inferior cerebellar artery was identified and preserved throughout the procedure. In addition, lower cranial nerves were identified and were noted to be well separate from the tumor. Similarly, cranial nerve V was identified and noted to be separate from the tumor. All these cranial nerves were preserved. Arachnoid adhesions were then fully separated from the cerebellum and the brainstem and the cochlear vestibular complex identified at the root entry zone. Just deep to the cochlear vestibular bundle, the facial nerve was noted to be exiting the brainstem. Brisk responses were obtainable at this stage.
Further dural opening was then performed over the internal auditory canal. The tumor appeared to be originating from the inferior vestibular nerve. The inferior vestibular nerve was avulsed and the internal auditory canal portion of the tumor was dissected. The plane between the facial nerve and the superior vestibular nerve in the tumor were identified and separated. Approaching the porus acusticus, the tumor was noted to be quite adherent to the facial nerve, and the facial nerve was noted to be quite splayed.
At this point, the cochlear vestibular complex was cut and tumor dissection performed from medial to lateral. Any blood vessels entering the tumor capsule were cauterized. All other blood vessels were preserved, including the petrosal vessels. The tumor was noted to be quite adherent to the facial nerve and this was a tedious dissection. Tumor was debulked. Frozen section came back consistent with a schwannoma and the tumor was then removed piecemeal. Gross total removal of the tumor was accomplished. There was some capsular tissue adherent to the region of the porus acusticus, where the facial nerve was most splayed. There was no identifiable plane between this tissue and the nerve, hence it was left in place.
With the tumor removed, the superior, inferior, and cochlear nerves were all removed with the tumor. The facial nerve was preserved throughout the procedure. The wound was copiously irrigated. There was noted to be excellent hemostasis. The patient was placed in Trendelenburg position with multiple Valsalva attempts. There was no evidence of bleeding. Stimulation of the facial nerve at its exit from the brainstem revealed brisk responses at 0.1 milliampere with the responses of 1100 microvolts at 0.5 milliampere, stimulation responses were obtained at 294 microvolts. Periosteal soft tissue was harvested for packing of the middle ear cleft. In addition, attention was then turned to the abdomen.
A horizontal incision was made between the umbilicus and the pubic bone. This was carried down to the level of the abdominal fat. A fat graft was harvested and excellent hemostasis obtained. A Jackson-Pratt drain placed through the inferior flap. The incision was then closed in layers. Drain was secured. The harvested periosteum was then cut into strips and the entire middle ear cleft and the eustachian tube were packed.
Bone wax was used to seal up any exposed air cells. The prior harvested fascia graft was then draped along the mastoid segments of the facial nerve and overlying the entrance into the epitympanum covering the entire space. The harvested fat graft was then cut into strips. Small strips were placed to fill the dural defect. In addition, further fat strips were placed into the mastoid defect. The periosteal layer was then closed with an interlocking suture, locking the fat into place. There were never any traumatic EMG potentials during this portion of the procedure.
The postauricular incision was then closed in two layers. The skin was then closed with a running interlocking Prolene suture. The ear canals were cleared of any debris. A sterile compressive mastoid dressing was applied. All neural monitoring needle electrodes were then removed. The sponge counts were accurate at the end of the procedure. A sterile dressing was applied to the abdomen as well. The patient was then awakened by the anesthesia service, extubated, and taken to the recovery room in stable condition. There were no intraoperative complications. The patient tolerated the procedure well.
In the postoperative recovery room, the patient was following commands and moving all four extremities equally. In addition, the patient with a mild facial weakness on the left side, graded as a House-Brackmann grade 2. She has a complete strong eye closure. Overall, she tolerated the procedure well and there were no complications.
