S-100 protein in cerebrospinal fluid of patients with subarachnoid haemorrhage: a potential marker of brain damage.

Concentrations of S-100 protein in cerebrospinal fluid (CSF) were measured by a recently developed radioimmunoassay (RIA) in 45 patients with subarachnoid haemorrhage (SAH), 44 with verified ruptured aneurysm. In each of 43 patients 2-15 serial CSF samples were analysed, and in the remainder 1 sample was examined. The concentrations of S-100 protein proved to be related to the brain damage caused by the SAH, indexed as outcome (Glasgow Outcome Scale). The S-100 concentrations were related to the severity of the haemorrhage and to the development of delayed ischaemic deterioration. Delayed ischaemic deterioration (vasospasm) was usually accompanied by an increase in CSF S-100 concentration after 4 days. Patients in whom no S-100 value exceeded 20 ng S-100 per ml during the course of the disease had a favourable outcome, whereas patients in whom one or several CSF samples contained more than 100 ng/ml became severely disabled or vegetative or died. The present study suggests that CSF S-100 analysis may be used as an objective and early measure of the degree of brain damage sustained by the SAH patient.