After any form of craniotomy, hydrocephalus may occur at a later stage, the most reason is that during craniotomy, there will be a certain tendency of bleeding, once the bleeding is deposited inside the brain, it will gradually flow away with the circulatory pathway of cerebrospinal fluid, in the process of flowing away, there are holes or narrow and small pipelines, the cells will gradually accumulate, if the accumulation is more serious, it will If the accumulation is serious, it will block the normal circulation pathway of hydrocephalus and eventually cause hydrocephalus to occur. Once the arachnoid granules are blocked, the normal secretion and absorption function of cerebrospinal fluid will be affected, which may also cause hydrocephalus.