Pediatric medulloblastoma
Introduction
Introduction to pediatric medulloblastoma Medulloblastoma is a common intracranial tumor in children. It is mainly characterized by cerebellar symptoms such as increased intracranial pressure and ataxia. It often has diplopia and multiple cranial nerve disorders. Cerebellar tonsils often have neck stiffness. The torticollis showed an average disease duration of about 4 months. basic knowledge The proportion of illness: 0.005% Susceptible people: children Mode of infection: non-infectious Complications: hydrocephalus
Cause
Pediatric medulloblastoma etiology
(1) Causes of the disease
Medulloblastoma This disease is a common central nervous system tumor, which is a highly malignant tumor. It originates from the cerebellar vermis or the fourth ventricle. The posterior medullary primitive embryonic residual tissue, which accounts for 10 of children's primary brain tumors. % to 20%, 40% of posterior fossa tumors occur in children.
(two) pathogenesis
Tumors located in the cerebellar palsy accounted for about 80%, most of them protruded into the fourth ventricle. The older ones (13-15 years old) were located in the cerebellar hemisphere. Some people explained that medulloblastoma originated from the myeloid proliferation center, while the older ones It can be developed from the residual cells of the extragranular extragranular layer. A very small number of tumors can progress to the upper cervical spinal canal (ie, the descending occipital macropore tumor in the brain) through the occipital macropores. The tumor is highly malignant and often has tumor cells falling off. Dissemination and transfer along the cerebrospinal fluid can be planted in the cauda equina, spinal cord or brain surface, ventricles, etc., and some people with cranial spinal cord metastases account for 12% to 46%.
Pathogenesis
At present, according to the characteristics of certain tumors, pathology and some basic experimental research, several theories are proposed.
(1) Genetics: In the field of neurosurgery, some tumors have obvious family tendencies, such as retinoblastoma, vascular reticuloma, multiple neurofibromas, etc., which are generally considered to be autosomal dominant. Hereditary tumors have a high penetrance rate.
(2) Virology: Experimental studies have shown that some viruses, including DNA viruses and RNA viruses, can induce brain tumors if inoculated into the brain of animals.
(3) physics and chemistry said: the physical factors identified in the tumor is likely to be radiation, there have been many reports of intracranial tumors caused by cranial radiotherapy, in chemical factors, polycyclic aromatic hydrocarbons and nitric acid compounds, such as Methylcholine, benzopyrene, methylnitrosourea, nitrosopiperidine, can induce brain tumors in some animal experiments.
(4) Immunosuppression theory: the application of organ transplant immunosuppressive drugs will increase the risk of intracranial or peripheral tumors.
(5) Embryonic residual theory: craniopharyngioma, epithelioid and dermoid cysts, teratoma, chordoma obviously occur in the embryonic tissue remaining in the brain, these residual tissues have the potential of proliferation and differentiation, under certain conditions Developed into a tumor.
2. Classification
There are many methods for classification of central nervous system intracranial tumors. The most representative ones are the following. See Table 1. The classification of Bailey and Cushing can reflect the source and malignancy of tumor tissue. It has long been used in neurosurgery in most parts of the world. The pathology department used, based on this, some new classification methods were derived, such as Kernohan's I-IV classification, Russell's glioma classification, and more influential is that Kernohan proposed to include gliomas, including astrocytes. Tumors, oligodendrogliomas, ependymoma, and neurogenic tumors are classified into grades I-IV according to their degree of differentiation. According to this classification, it seems that the development of tumors and the prognosis of patients can be easily judged, so they are clinicians. Welcome, used in domestic and international for many years, but this classification is also flawed, such as the same tumor in different parts, cell differentiation can be different, some mixed tumors can not be graded, and some tumors are not meaningful, on this basis, the World Health Organization A new taxonomy has been developed, which is characterized by a detailed classification, including various types of tumors that occur in the brain, and absorbs various classifications Features and advantages, both to reflect the tumor morphology, but also indicate the source of the tumor, and the use of change between this concept can be considered as the best classification.
Tumor cells can be disseminated to the subarachnoid space with the cerebrospinal fluid or transferred to the extracranial cavity, up to 11% to 43%. The tumor tissue is grayish red or purple red, soft and fragile, the boundary is unclear, and the tumor cells are dense under the microscope. The nucleus is round or elliptical, deeply stained, with many mitotic divisions, less cytoplasm and interstitial, and some are arranged in the form of fake daisy.
Prevention
Pediatric medulloblastoma prevention
1. Avoid harmful substances (promoting factors)
It is able to help us avoid or minimize exposure to harmful substances.
Some related factors of tumorigenesis are prevented before the onset, and many cancers can be prevented before they are formed. A report in the United States in 1988 compared the international malignant tumors in detail and proposed many external factors of known malignant tumors. In principle, it can be prevented, that is, about 80% of malignant tumors can be prevented by simple lifestyle changes, and traced back. In 1969, Dr. Higginson's research concluded that 90% of malignant tumors are caused by environmental factors," "Environmental factors", "lifestyle" refers to the air we breathe, the water we drink, the food we choose to make, the habits of activities, and social relationships.
2. Improve the body's immunity against tumors
Can help to strengthen and strengthen the body's immune system and cancer.
The focus of our current cancer prevention efforts should first focus on and improve those factors that are closely related to our lives, such as quitting smoking, eating properly, exercising regularly, and losing weight. Anyone who follows these simple and reasonable lifestyles can Reduce the chance of cancer.
The most important thing to improve the function of the immune system is: diet, exercise and control troubles. Healthy lifestyle choices can help us stay away from cancer. Maintaining good emotional state and proper physical exercise can keep the body's immune system at its best. Tumors and prevention of other diseases are equally beneficial. Other studies have shown that appropriate activities not only enhance the body's immune system, but also reduce the incidence of colon cancer by increasing the peristalsis of the human intestinal system. Here we mainly understand the diet in preventing tumorigenesis. Some questions.
Human epidemiology and animal studies have shown that vitamin A plays an important role in reducing the risk of cancer. Vitamin A supports normal mucosa and vision. It directly or indirectly participates in most of the body's tissue functions. Vitamin A is present in animal tissues. In the liver, whole eggs and whole milk, the plant is in the form of -carotene and carotenoids, which can be converted into vitamin A in the human body. Excessive intake of vitamin A can cause adverse reactions in the body and -carrot This is not the case with carotenoids, and the low vitamin A content in the blood increases the risk of malignant tumors. Studies have shown that those with low levels of vitamin A intake in the blood increase the likelihood of lung cancer, while those with low blood levels in smokers Levels of vitamin A ingestors have the potential to double lung cancer. Vitamin A and its mixture can help remove free radicals in the body (free radicals can cause damage to genetic material), and secondly stimulate the immune system and help differentiate cells in the body. Ordered tissue (while the tumor is characterized by disorder), some theories suggest that vitamin A can help early carcinogens Invasion mutated cells become reversed the occurrence of the normal growth of cells.
In addition, some studies suggest that supplementation with -carotene alone does not reduce the risk of cancer, but rather increases the incidence of lung cancer. However, when -carotene binds to vitamin C, E and other antitoxin substances, its protective effect. It is shown, because it can increase free radicals in the body when it is consumed by itself. In addition, there are interactions between different vitamins. Both human and mouse studies have shown that the use of -carotene can reduce 40% of vitamins in the body. At E-level, a safer strategy is to eat different foods to maintain a balanced vitamin to protect against cancer, as some protective factors have not been discovered so far.
Vitamin C, E is another anti-tumor substance that prevents the harm of carcinogens such as nitrosamines in food. Vitamin C protects sperm from genetic damage and reduces the risk of leukemia, kidney cancer and brain tumors in their offspring. Vitamin E can reduce the risk of skin cancer. Vitamin E has the same anti-tumor effect as vitamin C. It is a scavenger that protects against toxins and scavenges free radicals. The combination of vitamins A, C and E protects the body against toxins. Better than applying it alone.
At present, research on phytochemistry has attracted widespread attention. Phytochemistry is a chemical found in plants, including vitamins and other substances found in plants. Thousands of plant chemicals have been found, many of which have anticancer properties. The protective mechanism of these chemicals not only reduces the activity of carcinogens but also enhances the body's immunity against carcinogens. Most plants provide antioxidant activity that exceeds the protective effects of vitamins A, C, and E, such as a cup of cabbage. Contains 50mg of vitamin C and 13U of vitamin E, but its antioxidant activity is equivalent to the antioxidant activity of 800mg of vitamin C and 1100u of vitamin E. It can be inferred that the antioxidant effect in fruits and vegetables is far better than what we know. The effect of vitamins is strong, and no doubt natural plant products will help prevent cancer in the future.
Complication
Pediatric medulloblastoma complications Complications hydrocephalus
Combined with chronic cerebellar tonsil, it can cause neck resistance or forcing the head position by stimulating the upper cervical nerve root. When the tumor invades the facial mound, it can spread and facial nerve paralysis. The spinal cord metastasis can cause paraplegia.
First, bleeding
Hemorrhage after surgery in the fourth ventricle and cerebellar sac tumors may cause acute obstructive hydrocephalus or direct compression of the medullary respiratory center to cause respiratory arrest. If there is lateral drainage outside the brain before surgery, it can help identify whether there is postoperative bleeding. A small amount of oozing can be relieved by drainage outside the brain; if the amount of bleeding is large, secondary surgery is necessary to stop bleeding.
Second, breathing stops
Pulling or directly injuring the medullary respiratory center during surgery, or bleeding edema after surgery, can cause respiratory arrest. Injury of the anterior or posterior inferior cranial artery causes a brain stem infarction caused by retrograde embolism and can also cause respiratory arrest.
Third, intracranial gas
It is related to excessive loss of cerebrospinal fluid and high intraoperative head position. In severe cases, a tensional gas skull can be formed. Gas can be located in the subdural, longitudinal fissure, cerebral cistern or lateral cerebral ventricle.
Fourth, hydrocephalus
Many cases of tumor resection are not completely postoperative aqueduct adhesion, surgical area adhesions, effusion, postoperative infection, brain tissue edema and other factors. For the cause of hydrocephalus, measures can be taken to relieve obstruction or lateral ventriculo-peritoneal shunt.
Symptom
Pediatric medulloblastoma symptoms Common symptoms Ataxia swallowing sputum gait instability muscle tension reduction dilated intracranial pressure increased neck tonic closed eyes difficult to sign eyeball tremor bone separation
Mainly manifested as cerebellar symptoms such as increased intracranial pressure and ataxia, invasive brainstem often have diplopia and a variety of cranial nerve disorders, cerebellar tonsil tendon often have neck stiffness, torticollis, due to tumor majority obstruction of the fourth ventricle The intracranial pressure is increased, and the average disease duration is about 4 months.
1. Increased intracranial pressure manifested as headache, vomiting and optic disc edema. This group of headaches accounted for 76.6%, vomiting accounted for 95%, optic disc edema accounted for 72.1%, and smaller children may have cranial sutures.
2. The cerebellar damage sign is mainly due to the trunk ataxia caused by cerebellar sacral damage, gait instability and standing shaking, Romberg sign positive, tumor compression medulla may have swallowing bun and pyramidal tract sign, 2 / 3 of the disease Children showed low muscle tone and low sputum reflexes. Some patients had nystagmus and limbs. The group had 88.3% of cerebellar signs.
Examine
Pediatric medulloblastoma examination
Lumbar puncture: cerebrospinal fluid pressure increased, biochemical protein and leukocytosis accounted for 1/5, because the tumor cells can fall off and spread, so cerebrospinal fluid tumor cell examination is very important, but for those with optic disc edema should be careful to avoid cerebral palsy .
1. The skull X-ray film shows signs of increased intracranial pressure, and tumor calcification is extremely rare.
2. CT can be seen in the cerebellar or four-chamber uniform uniform density or slightly higher density occupying space, and more with the fourth ventricle at the bottom of the boundary, the brain stem forward, surrounded by a thin low-density edema zone, significantly uniform Intensive, tumor calcification sac becomes rare.
3. The MRI tumor parenchyma is characterized by a long T1 long T2 signal. The sagittal position can better show the relationship between the tumor originating from the cerebellum and the tumor and the fourth ventricle. This can be regarded as the identification point of the ependymoma. .
Diagnosis
Diagnosis and diagnosis of medulloblastoma in children
diagnosis
Preschool or school-age children, especially boys, have unexplained headaches, vomiting, gait instability, nystagmus, and diplopia. First, the possibility of medulloblastoma should be considered. Further neurological examination should be performed to confirm the diagnosis. Some children can be diagnosed by finding detached tumor cells in the cerebrospinal fluid. The medulloblastoma is easy to spread and metastasize. If the posterior cranial tumor has intraventricular dissemination, the disease can be diagnosed before operation.
Differential diagnosis
Different from the causes of increased intracranial pressure and ataxia, it can be diagnosed by clinical manifestations and laboratory, auxiliary examination, but medulloblastoma should be differentiated from ependymoma: ependymoma originates from the fourth ventricle The ependymal cells in the bottom or side wall, the boundary between the tumor and the four-chamber bottom is unclear, and can grow along the ventricle side hole to the cerebellopontine angle of the cerebral ventricle, extending into the spinal canal through the occipital foramen and even surrounding the medulla and cervical spinal cord, thus the brain stem Symptoms of compression appear earlier, and neuroimaging is also characteristic.
