THE NEURONAL ENVIRONMENT AFTER SUBARACHNOID HEMORRHAGE - CORRELATION OF AMINO-ACID AND NUCLEOSIDE LEVELS WITH POSTOPERATIVE RECOVERY

The study explores biochemically the neuronal environment adjacent to a subarachnoid haemorrhage in 11 patients after neurosurgical clipping of an arterial aneurysm. Extracellular fluid (ECF) from the rectus gy rus and subarachnoid fluid (SAF) were sampled with microdialysis probe s. The concentrations of amino acids and nucleosides were monitored in 60 min samples collected over 2-4 days. The patients were 33-67 years of age. Surgery was performed 0-5 days after rupture of the aneurysm in 8 patients. One patient was operated on after 15 months. Clipping o f aneurysms without prior haemorrhage was performed in two cases. Mark edly elevated concentrations of the excitatory amino acid glutamate wa s observed in the ECF of only one patient who underwent surgery within 8 hours after the haemorrhage. Moderate glutamate elevations were see n in two patients and of aspartate in another patient. Five patients d isplayed periods of varying length of specifically elevated taurine co ncentrations in ECF or SAF. Transient periods of high concentrations o f glycine and serine were seen in two patients. Even though average co ncentrations of all amino acids were fairly similar in the ECF and SAF , the pattern of changes vs. time differed markedly in the two compart ments. Presently, we conclude that the level of consciousness in the p ost-operative phase was inversely related to total amino acid concentr ation in the ECF. Furthermore, while the ECF concentrations of taurine and glycine increased both specifically and transiently in several pa tients, excitatory amino acid levels were not appreciably elevated sub sequent to the neurosurgical intervention. No pattern of amino acid co ncentrations could clearly serve as an indicator of haemorrhage or dis turbed blood-brain barrier (BBB) function.