A brain tumor is an intracranial tumor, classified as benign or malignant, which is mainly an abnormal growth of a small part of nerve cells or surrounding tissues in the skull, like a weed, constantly encroaching on the surrounding land, thus causing various uncomfortable clinical symptoms. Intracranial tumors can originate from both cranial structures and other structures, the former being called primary and the latter secondary. The causes of brain tumors have not been fully clarified yet, among which there are several possible causes.1. Genetic factors. For example, neurofibromatosis can have congenital malformations, and a few gliomas can be hereditary, etc. 2. Viruses. Although a variety of viruses have been found to induce brain tumors, direct evidence has not been obtained.3. Physical factors. For example, some research studies have shown that radiation can cause glioma, etc. 4, chemical factors. For example, ethylene chloride is the most likely chemical agent to cause human brain tumor. 5.Congenital factors. The common congenital tumors are craniopharyngioma and so on. The clinical symptoms caused by brain tumor are very strange, the most common ones are dizziness, headache, nausea and vomiting, some of them may also show mental symptoms, such as slow reaction, memory loss, and consciousness impairment, as well as drowsiness and even coma. Some seizures may also occur, causing speech dysfunction and numbness of the limbs due to the violation of the motor nerve centers. Sometimes there is also loss of vision and visual field defects, ataxia, etc. Therefore, if abnormalities occur, it is important to go to the hospital for relevant examinations to clarify the nature of the pathology and provide relevant treatment in a timely manner.