Duration of glutamate release after acute ischemic stroke

High levels of glutamate in plasma and cerebrospinal fluid (CSF) have been demonstrated in patients with acute ischemic stroke. The duration of this excitatory amino acid release has not been studied, and therefore the window of opportunity of treatment with glutamate antagonists is unknown. The aim of this investigation was to study the duration of the glutamate increase in patients with stable and progressing ischemic stroke.

Glutamate in CSF was measured by high-performance liquid chromatography in 184 patients with an acute cerebral infarction of less than 24 hours' duration and in 43 control subjects.

Among the 120 patients with stable ischemic stroke, median glutamate levels were significantly lower- and within the reference range of control subjects-in those patients studied 6 to 24 hours from onset of symptoms than in patients studied in the first 6 hours (3 [range, 2 to 10] versus 5 mumol/L [range, 2 to 17]; P < .0001). In 64 patients with progressing ischemic stroke, glutamate concentrations measured at any time interval during the first 24 hours from onset were significantly higher than in the stable stroke and control groups.

The presence of glutamate increase in the CSF cannot be documented for greater than 6 hours in stable ischemic stroke. The sustained elevation of glutamate observed in progressing stroke suggests that the window to prevent neurological deterioration may be wider.