pontomedullary tumor resection

Brain stem tumors are mostly gliomas, of which astrocytic tumors (including glioblastoma) are the majority, and the rest are ependymoma, oligodendroglioma, and mixed glioma. Hemangioblastoma (vascular reticuloma) is also not uncommon. In addition, a spongy malformation (spontaneous hemangioma) that has been pathologically classified into a vascular malformation can also be seen. According to the location of the tumor, the bridge brain is mostly, the midbrain and the medulla are less, but sometimes it can affect the entire brain stem. Tumors originating in the medulla oblongata may still involve the upper cervical spinal cord. Brain stem tumors can occur in all age groups, but they are more common in children and young people, and also in middle-aged and old age. Tumors are invasive, but some are nodular or mixed, or cystic. The clinical manifestations vary in the location, extent and extent of the brain stem damaged by the tumor, and the intracranial pressure may increase in the late stage. The blood supply to the tumor comes from the vertebral-basal artery and the branch of the posterior cerebral artery. Tumors with limited, nodular, and well-differentiated brainstem gliomas are suitable for surgical treatment and can achieve certain effects. Postoperative survival with radiotherapy can prolong survival. The incidence of brainstem spongiform deformity is increasing in the MRI era. Pathologically, it has been classified into vascular malformation, but due to its repeated hemorrhage (annual bleeding rate of each lesion is about 5%), the lesion gradually increases and plays a role in the brainstem, so it tends to be treated as a tumor. The brainstem cavernous vascular malformation has a worse prognosis than other cavernous vascular malformations. For patients whose lesions have protruded into the pia mater, surgical resection should be considered. The cavernous vascular malformation in the brain is different from the cavernous vascular malformation of the parasagittal and cavernous sinus. It is a cluster of abnormal blood vessels, the blood supply artery is small, and there is a thrombotic material in it, which has a clear boundary with the surrounding brain tissue. Change and gliosis), resection is easier. However, it should be noted that there is often a developmental venous abnormality (DVA) around the lesion, which is the blood outflow pathway of normal brain tissue and therefore cannot be damaged. Hemangioblastoma is more common in the medulla, the dorsal aspect of the bridge junction or the dorsal side of the cervical spinal cord. The blood supply is very abundant. If the blood supply artery (mainly from the posterior inferior cerebellum) can be processed first in the operation, the tumor can be completely removed. , and achieved satisfactory results. Surgery should be done under the microscope. At present, the indications for surgical resection of brain stem tumors are mainly from the brain stem, but the boundary is relatively clear and grows to the outside of the brain stem. The choice of brainstem surgery approach is based on where the tumor has broken through the brain stem or closest to the surface of the brain stem. This area generally shows bulging, pale, and in addition to vascular tumors, generally local blood vessels are reduced. Since the function of the brainstem has been affected here, no new symptoms or only slight aggravation can be added after the incision. Sometimes, after the lesion is removed, the oppression is relieved, and the symptoms are alleviated. Of course, it should be emphasized that surgery can cause serious damage to the brain stem, especially those involving the medullary respiratory center, cardiovascular center, and midbrain reticular formation. Therefore, in-depth study of the practical anatomy of the brain stem and the anatomical location of important structures are also an important topic in clinical practice. Kyoshima and other researchers proposed two "safe" bands that enter the brainstem through the fourth ventricle: one is the suprafacial triangle, the inner boundary is the medial longitudinal bundle, and the tail is the facial nerve (intracerebral segment). The outside is the cerebellum; the other is the infrafacial triangle, whose inner boundary is the medial longitudinal bundle, the tail is the medulla, and the outside is the facial nerve. In these two triangles, the important structures are not densely arranged, and the blood supply to the brainstem parenchyma is mainly from the ventral and lateral arterial perforating branches, rather than the surface of the fourth ventricle, by these two triangles. It is relatively safe to enter the brainstem. Of course, the deep side of the ventral side of these two triangles is the inner mound, which cannot be damaged. Entering the bottom of the fourth ventricle and close to the dorsal side of the brainstem usually requires separation of the cerebellar vermis, but sometimes it can damage the dentate nucleus. Cutting the chin can damage the cerebellar fibers associated with the vestibular system, causing the caudal tail. Caudal vermis syndrome, which causes dysarthria, silence, and tonic ataxia. According to the anatomical features of the "cerebello-medullary fissure" reported by Matsushima and Rhoton, in recent years, the fourth ventricle and the posterior aspect of the brain stem have been exposed, eliminating the need to remove the cerebellar vermis (but sometimes need to be removed). tonsil). The cerebellar medullary fissure is the cerebellar tonsil and the second ventral lobe; the caudal end is the medulla, choroid plexus and lateral crypt. The cerebellar medullary fissure can extend to the top of the fourth ventricle, and enter the cisterna magna and cerebellar pons. The cerebellar medullary fissure divides the cerebellar tonsils from the medulla, which is a safe and natural path to the fourth ventricle and the lateral side of the brainstem. The surgical approach of the brainstem generally has the following options: 1 pterional approach, suitable for tumors at the cerebral and interdental fossa; 2 subtalar approach, suitable for the midbrain and the upper half of the pons ; 3 under the pillow - cerebellar approach, for the midbrain posterior, posterior lateral tumor; 4 under the cerebellum approach, there are central, lateral central, lateral and extreme lateral approach, suitable for Tumors in the posterior and posterior cerebral ventricles; 5 occipital posterior median approach, suitable for tumors in the pons and the medial dorsal medulla; 6 suboccipital-emulsion and suboccipital-polar lateral approach, suitable for pons, Tumors on the lateral side of the medulla. Treatment of diseases: brain stem tumors Indication The cerebral medullary tumor resection is suitable for all types of tumors of the medulla oblongata. The range is limited, and it is nodular or cystic, and the whole body is in good condition. Contraindications 1. Extensive invasive pons medullary glioma, the patient has central respiratory disorders. 2. The situation around the body has been exhausted. Preoperative preparation 1. There must be a correct positioning diagnosis before surgery. In recent years, due to advances in imaging inspection technology, clinical applications such as CT, MRI, and DSA have become increasingly widespread. The relationship between the location of the lesion and the surrounding structure should be analyzed before surgery in order to select the appropriate surgical approach, to obtain the best exposure, avoid the important structure of the skull as much as possible, increase the safety of the operation and strive for good Effect. 2. Skin preparation, wash the head with soap and water 1 day before the operation, shave the hair on the morning of the operation. You can also shave your head on the eve of surgery. 3. Fasting the morning of surgery. 4. Give phenobarbital 0.1g orally before surgery to ensure a quiet rest. One hour before the operation, 0.1 g of phenobarbital, 0.4 mg of atropine or 0.3 mg of scopolamine were intramuscularly injected. Surgical procedure 1. The incision takes a straight incision in the posterior cranial fossa. If the tumor is biased to one side, a lateral straight incision on the tumor side may also be used. 2. The craniotomy step is the same as the posterior fossa decompression. 3. After incision of the dura mater, observe whether the cerebellar hemisphere and the shape of the ankle are bulging. If the pons and medullary tumors grow to one side of the cerebellar hemisphere, the lateral hemisphere may be swelled, and the position of the tonsils may be lower than the contralateral side. When the tumor is explored, the cerebellar hemisphere is retracted to the midline by a brain pressure plate, and the medullary tumor can be found. The pons tumor grows mostly to the cerebellopontine angle, and the medullary tumor can protrude to the side. Glioma is mostly taupe or purple brown. Find the adjacent relationship between the cranial nerves and the tumors of the 5th, 7th, 8th, 9th, 10th, and 11th. The tumor is selected from the vasospasm in the avascular zone, and the electrocoagulation is a little. From this point to the deep puncture, if there is a cyst change, withdraw Cyst fluid. The cerebral medullary tumor was cut in the lateral side, and the tumor tissue and biopsy were clamped to confirm the tumor properties. 4. Nodular tumors can be carefully removed along the tumor boundary by biopsy forceps, and generally invasive can absorb tumor tissue. 5. In the operation of the intramedullary tumor in the brainstem, do not pull too much, especially beyond the tumor, so that aspiration of the brain stem normal tissue. Small oozing points are pressed with cotton sheets to stop bleeding. Small blood vessels are hemorrhaged by bipolar coagulation, and only weak current can be used to avoid injury to the important structure of the brain stem. Tumor tissue that grows to the cerebellar hemisphere is simultaneously removed, but those that infiltrate to the bottom of the fourth ventricle are not suitable for hyperactivity. 6. Surgical methods for hemangioblastoma Because of the rich blood supply to the tumor, it is forbidden to remove the block. The weak blood current should be used to electrocoagulate into the blood supply artery of the tumor and coagulate the blood vessels on the surface of the tumor. Then carefully separate the tumor from the brain dry surface, while stopping bleeding, while releasing the tumor, until the tumor is separated from the brain stem, and then completely removed. The trunk of the inferior cerebellar anterior and posterior inferior cerebellum cannot be clamped or electrocoagulated. 7. Wash the wound, completely stop bleeding, suture the dura mater, place the drainage tube on the tumor bed if necessary, and perform closed drainage. Stitch the muscle layer, subcutaneous tissue and skin. complication 1. Concurrent brain stem injury, postoperative coma, central respiratory and circulatory failure, need assisted breathing or tracheotomy. 2. Brain stem edema causes tonic seizures, routine use of sedatives such as phenobarbital, diazepam and so on. 3. When high fever occurs, hibernation hypothermia is used. 4. Special attention should be paid to respiratory changes and stress ulcers.