The most likely cause of high cerebrospinal fluid leukocytes is an intracranial infection. The most common causes of intracranial infection are the following: i. Bacterial meningitis: This is the most common cause of high leukocytes, and generally patients with bacterial meningitis have very high leukocytes. Second, viral meningitis: viral meningitis can cause high white blood cells. Meningitis caused by tuberculosis bacilli: Meningitis caused by tuberculosis bacilli can cause an increase in white blood cells. Fourth, radioencephalopathy: there are some other radioencephalopathies or some blood diseases, such as lymphoma, leukemia and so on. We need to analyze and judge which disease is caused by the clinical symptoms, imaging examination, and the characteristics of cerebrospinal fluid examination.