Lumbar puncture is short for lumbar puncture, which is not a “spinal tap”. It is performed by passing a puncture needle between two adjacent vertebral spaces in the lumbar region, measuring intracranial pressure, and taking a certain amount of cerebrospinal fluid for testing. It can determine whether there are lesions in the brain and spinal cord and the cause of the lesions; determine whether there is intracranial hemorrhage, inflammation, meningeal carcinoma; determine the level of intracranial pressure, whether there is obstruction or compression in the spinal cord cavity; anesthesia for surgery; and intraspinal injection of drugs including chemotherapy drugs, antibiotics and anesthetics, as well as air or oxygen for therapeutic purposes (often called intrathecal injection). The cerebrospinal fluid can be examined by taking only a few milliliters of specimen and sending it for testing. The total amount of cerebrospinal fluid averages 150 mL in normal adults, and the brain can produce 0.35 mL per minute, which can be replaced about once every 8 hours, so the cerebrospinal fluid can be replaced rapidly. This means that a few milliliters of cerebrospinal fluid taken during a lumbar puncture will not cause any damage to the body. The doctor will do lumbar puncture as needed, and the puncture needle is about the same thickness as an intramuscular injection needle, and the operation itself is very safe. There is no basis for the claim that lumbar puncture can make people stupid. As for the fact that some intracranial disorders affect the patient’s intelligence, it has nothing to do with lumbar puncture itself. People who need lumbar puncture often have intracranial lesions, which themselves may cause mental retardation or paralysis, but obviously not due to lumbar puncture. Refusal of lumbar puncture may delay the diagnosis and affect the treatment, with endless consequences.