Infratentorial and supracerebellar approach for tumor surgery of the third ventricle and pineal region

Krause first succeeded in this approach in 1926. In 1971, Stein made an important contribution to re-evaluating this approach. Domestic Yang Qingyu adopted this approach in 1981, Luo Shiqi in 1983 and Huang Yanlin in 2000. Because the pineal region tumors are mostly located in the midline, the tumor can be well exposed through the posterior fossa pathway during the sitting operation. Tumors are mainly located below the great venous system of the brain to avoid damage to these veins. Because it is not necessary to pull the occipital lobe, it avoids vision and visual field obstacles. When the tumor is extended beyond the notch, or to the anterior portion of the third ventricle, there is difficulty in passing through the approach. Even if the cerebellum can be cut, it is still difficult to remove the front of the tumor. Treating diseases: brain tumors Indication Mainly adapted to the tumors in the pineal region that are not sensitive to radiotherapy, especially those who are posterior to the posterior fossa. Contraindications 1. When the pineal region tumors expand upwards. 2. Pineal area germ cell tumor should be the preferred radiotherapy. Preoperative preparation Ventricular drainage should be performed before surgery. Through this approach, surgical microscopes and long microsurgical instruments must be used. Because the surgical field distance is generally longer, ordinary instruments cannot meet the requirements. Surgical procedure Skin incision A midline incision under the pillow. The second cervical vertebra is delivered, and the upper and lower occipital trochanter. Use a periosteal stripper to separate the muscles from the occipital scaly to the sides to fully open the incision. 2. The bone window Generally, a larger pillow lower bone window is made. The transverse sinus and the lower edge of the sinus are exposed, and the posterior margin of the occipital foramen is removed. 3. Dural incision The d-shaped incision of the dura mater opens the dura mater upwards and to the sides. 4. Reveal the pineal body area After opening the dura mater, all the bridge veins that flow from the cerebellar hemisphere and the cerebellar upper iliac crest into the transverse sinus and sinus should be cut off to get close to the quadrilateral region and the cerebellar incision. Use a general or serpentine automatic retractor, one to lift the cerebellum up and the other to pull down the cerebellum. Gravity helps the cerebellum to sag automatically when sitting. In general, the arachnoid membrane in the quadrilateral region is often thickened, and the arachnoid is cut under a surgical microscope to reveal the tumor. The cerebral venous and intracerebral veins are usually above the tumor, and the medial aspect of the temporal lobe and the basal vein are visible on the outside. These veins converge upward in this area, and the thickened arachnoid covering the tumor can blur the anatomical structure below. Clear, cut arachnoid, the operation should be as close as possible to the cerebellar hemisphere and the front of the ankle, electrocoagulation and cut off the central vein of the cerebellum, then the cerebellum can further sag, revealing the back of the tumor. 5. Resection of the tumor Tumors are mostly supplied by branches of the posterior choroidal artery. The tumor capsule is electrocoagulated and then incised, and the intracranial resection is performed by using a tumor-clamp, a curette or an aspirator depending on the hardness of the tumor. Since most tumors are extended to the third ventricle, individual cases can even be extended to the interventricular septum, so some long surgical instruments are needed to remove the posterior portion of the third ventricle and even the more extended tumor. In general, the direction of the operation is toward the middle sail, and special care should be taken when attempting to remove the tumor in the lower part of the third ventricle to prevent damage to the hypothalamus. Carefully operate under a surgical microscope to achieve a full-cut tumor without increasing damage. For tumors that cannot be completely cut, the tumor volume can be reduced, or the cerebrospinal fluid circulation can be reconstructed by the tumor to the third ventricle, or the internal shunt can be directly placed into the third ventricle, through the tumor and the cerebellar hemisphere to the cisterna magna. . Or after surgery, a shunt should be performed if necessary to replace ventricular drainage. 6. Guan skull After the tumor is removed and the ventricular system is obstructed, the dura mater should be sutured. complication 1. Air embolism can occur when sitting, should pay attention to prevention. 2. Eye movement disorders: often accompanied by upper and collective movement disorders and pupillary dysfunction. Due to damage to the quadrilateral area, it is usually temporary.