The symptoms of CNS leukemia are manifested in the following ways: i. headache, nausea, violent vomiting; ii. seizures with twitching of limbs, foaming at the mouth and clenching of teeth; iii. limb paralysis, slurred speech, aphasia and even loss of consciousness. CNS leukemia requires lumbar puncture and cerebrospinal fluid examination to further clarify the diagnosis. For patients with clear CNS leukemia, treatment with lumbar puncture and intrathecal injection of chemotherapeutic drugs twice a week is required until the lumbar puncture cerebrospinal fluid examination turns negative for leukemia cells. After the leukemia cells have metastasized, another lumbar puncture once a week and a total of 2 intrathecal injections of chemotherapeutic drugs are required.