Resection of acoustic neuroma through the suboccipital retrosigmoid approach

Treating diseases: acoustic neuroma Indication Suboccipital sigmoid sinus approach for auditory neuroma resection for: 1. Acoustic neuroma grows to the cerebellopontine angle of the cerebellum. 2. An acoustic neuroma located in the internal auditory canal. Preoperative preparation 1. Giant acoustic neuroma has caused increased intracranial pressure. The cerebral ventricle is continuously drained 2 to 3 days before surgery. 2, more intubation general anesthesia. The airway must be kept open during surgery. Take the sitting position or the side prone position (park-bench position), the affected side is up. The head is fixed with a three-studded head frame. Surgical procedure Incision After the mastoid, the incision is made from the upper line 5cm down to the neck 4 plane. The barb-shaped incision is also used more. The skin, subcutaneous tissue and muscle layer are cut open to the occipital surface of the occipital bone, and the automatic retractor is used. Open the incision. 2. Craniotomy Under the upper line, the occipital bone hole is drilled, and the bone window is enlarged according to the size of the tumor: the upper boundary shows the lower edge of the transverse sinus, the lateral side is near the posterior edge of the sigmoid sinus, and down to the foramen magnum. The tumor is huge and can be cut after the atlas Bow, the inner line reaches the midline or exceeds the midline. 3. The trachoma is cut in a petal or radial shape and suspended by a wire. The cerebellar hemisphere is retracted to the medial side with a brain pressure plate, and the cerebellar medullary pool and the bridge arachnoid membrane are torn off, and the cerebrospinal fluid is discharged to reduce the intracranial pressure. Explore the cerebellar pons along the lateral side of the posterior cranial fossa. Tumors can be found when approaching the inner ear hole. The acoustic neuroma is mostly gray-purple or taupe, the tumor is degenerated, and the cystic change is yellow-brown. Sometimes the surface of the tumor adheres to the arachnoid or accumulates from the cerebrospinal fluid to form a cyst. 4. Excision of the tumor usually first coagulates the tumor capsule, longitudinally incision, and the tumor is removed with a suction device, biopsy forceps or curette. If there is more bleeding when the tumor is removed, it can be freed from the periphery of the tumor and enter the lower pole of the tumor. The small blood supply arteries on the medial and superior poles are electrocoagulated and then cut off, and then the tumor is removed from the capsule. The more the tumor tissue is removed within the capsule, the better the tumor capsule collapses, which is conducive to tumor resection. 5. Separate the tumor from the ninth, 10th, and 11th cranial nerves, and then release the inner side of the tumor from the upper pole. When the upper pole is released, the branch from the superior cerebellar artery to the tumor must be electrocoagulated and cut off. The tumor is then separated from the trigeminal nerve. If the tumor has protruded upward into the cerebellar lobes, the tumor is carefully pulled down for segmentation. The tumor capsule was pulled to the outside to see the facial nerve located in front of the tumor, so that the facial nerve was released from the tumor capsule to the inner ear hole. The tumor is then cut from the inner ear hole and the tumor is removed. The tumor tissue remaining in the inner ear hole can be opened by the high-speed micro drill to open the posterior wall of the inner ear canal, and the tumor part in the inner ear canal is exposed, and the facial nerve is not damaged. When the tumor has been basically removed from the capsule, it is sometimes difficult to separate because the inner side is closely adhered to the brainstem or embedded in the brainstem. For example, forced stripping will aggravate brain stem damage. Surgery can be performed in most cases, and bipolar electrocoagulation is used to coagulate the residual tumor and destroy the tumor tissue. The cystic acoustic neuroma has a tight adhesion to the brainstem and cranial nerves, and the interface is unclear. It is especially necessary to identify it carefully during the operation. 6. Carefully stop bleeding, flush the wound, place the drainage tube on the tumor bed, and perform closed drainage. After successful total tumor resection, the dura mater can be sutured, and the muscular layer, subcutaneous and skin layers can be sutured layer by layer. 7. If the tumor is huge, exceed the midline, double incision surgery is optional. That is to do the midline of the posterior cranial fossa incision, extensive decompression Resection of the tumor from the lateral incision is beneficial to the full exposure and excision of the tumor. Postoperative decompression is also convenient, making the postoperative smoother. complication 1. Meningitis: postoperative local compression and dressing is not enough, forming a pseudocyst, secondary infection. 2. Facial nerve injury: This complication has been significantly reduced under the application of microsurgical techniques. 3. Brain stem injury: The surgery directly damages or damages the supply artery. 4. The 9th and 10th cranial nerve injuries. 5. The 5th and 7th cranial nerve injuries cause corneal ulcers.