Assessment of damage to the central nervous system by determination of S-100 protein in the cerebrospinal fluid.

S-100 protein was determined by Particle Counting ImmunoAssay in the CSF of patients with various neurological disorders. With a limit of sensitivity of 2.5 micrograms/l this brain-specific protein was detected only in samples from patients with acute damage of the central nervous system, particularly in compression of the spinal cord by tumour, ischaemic disorders, subarachnoïd bleeding and haematoma, and viral or suspected viral infections. Our results support the assumption that S-100 is a reliable index of central nervous system damage and that changes in its concentration could have a prognostic value.