A watery fluid, continuously produced and absorbed, which flows in the ventricles (cavities) within the brain and around the surface of the brain and spinal cord. The CSF is produced by the choroid plexus, a series of infolded blood vessels projecting into the cerebral ventricles, and it is absorbed into the venous system. This fluid surrounds and protects the brain and spinal cord. Samples can be obtained by lumbar puncture . In the later procedure a needle is passed between vertebrae in the spinal column and into the cerebrospinal space and fluid collected.
This suggests that any number of leukemic cells inthe CSF identifies patients who may benefit fromintensified intrathecal chemotherapy,which effectively prevents CNS relapse in cases of intermediate- or high-risk ALL.