INCREASED TRANSMITTER AMINO-ACID CONCENTRATION IN HUMAN VENTRICULAR CSF AFTER BRAIN TRAUMA

THE concentrations of L-aspartate, L-glutamate, L-serine, glycine and gamma-aminobutyric acid (GABA) were determined in repeated samples of ventricular CSF from five patients with severe closed head injury. The values were compared with those obtained from five subjects undergoin g surgical treatment for intractable depression. In the head-injured p atients, the concentrations of aspartate, glutamate and glycine were 2 - to 8-fold higher and the concentration of GABA 56- to 317-fold highe r than control values; the concentration of serine was unaffected. Spe arman correlation analysis indicated that the concentration of glutama te significantly increased after injury (R(s) = 0.60, p < 0.0001, n = 42), reaching an average concentration of about 7 mu M 3 days after th e injury. This is probably sufficient to cause further excitotoxicity, which suggests the use of excitatory amino acid receptor antagonists as a treatment following severe head injury may require prolonged admi nistration for maximum therapeutic benefit.