(3) cerebrospinal fluid cytology to determine the presence of subarachnoid hemorrhage, diagnose the presence of meningeal cancer, tumor cerebrospinal fluid dissemination and other diseases through cerebrospinal fluid exfoliation cytology, dynamically observe the changes in cerebrospinal fluid, diagnose and judge the prognosis of the disease, and further guide drug therapy. Lumbar puncture can also regulate the balance of intracranial pressure by releasing cerebrospinal fluid and treat intracranial neoplastic diseases by intrathecal drug injection.