Brain tumor can cause patients to suffer from consciousness disorder and lead to coma. Human consciousness is maintained by the reticularis superioris structure in the brainstem within the cranium, and once the brainstem is compressed and the function of the reticularis superioris structure in the brainstem is impaired, human beings will suffer from consciousness disorder and lead to coma. Brain tumors that are very large in size and cause significant occupying effects lead to increased intracranial pressure, and brain herniation occurs after the intracranial pressure has increased to a certain degree, leading to brainstem compression. Once the brainstem is compressed, the reticularis superior structures within the brainstem will become dysfunctional due to ischemia and necrosis, resulting in coma. If the tumor is located directly in the brainstem, it will directly destroy the reticularis superior structures in the brainstem, which will also lead to coma.