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cerebrospinal fluid[sə¦rē·brō′spīn·əl ′flü·əd]
the liquid that circulates in the ventricles of the brain and spinal canal and in the subarachnoid space (under the arachnoidea) of the brain and spinal cord. Cerebrospinal fluid is formed by vascular plexuses, glandular cells, the epen-dyma and subependymal tissue of the ventricles of the brain, the arachnoidea, and the glia. Drainage is through the venous plexuses of the brain, sinuses of the dura mater, and the perineural spaces of the cranial and spinal nerves.
Cerebrospinal fluid serves as a water cushion that protects the brain and spinal cord from external forces. It regulates intracranial pressure and ensures the constancy of the internal medium. Tissue metabolism in the central nervous system is achieved through cerebrospinal fluid. In a healthy individual, the fluid is transparent and colorless. Adults have 100–150 milliliters of cerebrospinal fluid, which varies in specific weight from 1.006 to 1.007. The fluid is slightly alkaline, and its pressure varies at different levels of the central nervous system, depending on the position of the body. (Cerebrospinal pressure is 100–200 mm H2O in the horizontal position.) In its chemical composition, cerebrospinal fluid is similar to blood serum. It may contain from zero to five cells per cu mm and 0.22-.33 parts per thousand protein.
The diagnosis and treatment of various conditions is facilitated by lumbar puncture, which permits cerebrospinal pressure to be measured and the fluid to be extracted for analysis purposes. Damage to the central nervous system alters the pressure and composition (especially the ratio between proteins and cells) of cerebrospinal fluid. Cerebrospinal pressure increases in cases of drainage disorders, which may be caused by traumas of the skull and spine, brain tumors, and hemorrhages. Bacteria are found in the fluid during meningitis. Lange’s test and the benzoin test are used in diagnosing syphilis. The biochemical analysis of the sugar, chlorides, free amino acids, and enzymes contained in cerebrospinal fluid is useful in the determination of neuroinfections and epilepsy.
REFERENCESShamburov, D. A. Spinnomozgovaia zhidkost’. Moscow, 1954.
Burgman, G. P., and T. N. Lobkova. Issledovanie spinnomozgovoi zhidkosti. Moscow, 1968.
Makarov, A. Iu. Sovremennye biokhimicheskie issledovaniia likvora v nevrologii. Leningrad, 1973.
V. B. GELFAND