Excess glutamate levels in the cerebrospinal fluid predict clinical outcome of bacterial meningitis
M. Spranger, S. Schwab, S. Krempien, M. Winterholler, T. Steiner and W. Hacke
Department of Neurology, University of Heidelberg, Germany.
BACKGROUND: The clinical course of bacterial meningitis still is
characterized by a high mortality and frequent neurological deficits in
survivors. In addition to other potentially neurotoxic mediators of
inflammation, the excitatory amino acid glutamate, which has been
implicated in neuronal death in a variety of other neurological diseases,
may also be involved in the pathological process of bacterial meningitis.
OBJECTIVES: To investigate the prognostic value of the glutamate
concentration in the cerebrospinal fluid (CSF) of patients with bacterial
meningitis. PATIENTS AND METHODS: Thirty consecutive patients with
bacterial meningitis were included in a prospective study. The clinical
severity of the disease was assessed on admission and 14 days after the
beginning of antibiotic treatment by means of the Glasgow Coma Scale.
Studies of CSF were performed on admission and after 3 to 6 days. In
addition to standard CSF investigations, including cell count, cytologic
findings, protein analysis, glucose and lactate levels, and microbiological
tests, the concentration of glutamate in the CSF was measured by an
enzymatic assay. RESULTS: At admission, both CSF cell count and
concentration of glutamate correlated well with the severity of the
disease. After treatment, glutamate concentrations decreased significantly
to normal or only slightly elevated levels in 23 patients. However, in 7
patients glutamate levels remained markedly increased. In this group,
clinical outcome was significantly worse than in the group of patients with
low glutamate levels in the second CSF analysis. CONCLUSIONS: A prolonged
increase of glutamate levels in the CSF may predict poor clinical outcome
in patients with bacterial meningitis, possibly because of the sustained
neurotoxic effects of this excitatory neurotransmitter.
