Cancer that has metastasized to the brain may have no symptoms or may present with very severe neurological symptoms. At first, patients do not have any discomfort symptoms when the cancer spreads to the brain. As the disease progresses and the tumor in the brain grows larger, they start to experience milder symptoms of nerve compression or damage such as headache, weakness and blurred vision. If the tumor continues to grow and compress various functional brain areas, symptoms such as aphasia, blindness, paralysis and numbness of one side of the limb will appear. If the patient still does not go to hospital for treatment, when the tumor grows to a certain level and the pressure inside the skull becomes higher and higher, it will lead to brain tissue embedding into the physiological orifice in the brain to form brain hernia, then the patient will have drowsiness, coma and other disorders of consciousness, or even sudden respiratory and cardiac arrest and death.