The normal value of cerebrospinal fluid examination, the pressure is usually 80-180 mmHg, and the color is clear and transparent. The number of white blood cells inside the cerebrospinal fluid is <8, generally mononuclear cells are predominant, while the protein content inside the cerebrospinal fluid is 0.15-0.45 g/L, the chloride content is higher than blood chloride at 120-130 mmol/L, and the sugar content in the cerebrospinal fluid is generally 2.5-4.4 mmol/L, which is lower than blood glucose. If laboratory tests of cerebrospinal fluid suggest lower than normal values, it is important to look for any associated etiologies, such as infectious diseases of the central nervous system and demyelinating diseases, which can shift these values and play an important role in clinical diagnosis.