Early High Cerebrospinal Fluid Glutamate: A Potential Predictor for Delayed Cerebral Ischemia after Aneurysmal Subarachnoid Hemorrhage

Abstract

Delayed cerebral ischemia (DCI) is an important complication after aneurysmal subarachnoid hemorrhage (aSAH). Early identification of cerebrospinal fluid (CSF) markers is helpful for warning of impending DCI. This study assessed whether early high CSF glutamate levels can be observed in aSAH patients who later developed DCI. In this prospective clinical study, patients with normal pressure hydrocephalus or aSAH were enrolled. We found that the early CSF levels of glutamate were significantly elevated in aSAH patients compared to patients with normal pressure hydrocephalus. There was a significant difference in early CSF levels of glutamate between aSAH patients without DCI and with DCI. The early CSF levels of glutamate are significantly related to the Hunt and Hess grade, the World Federation of Neurological Surgeons (WFNS) grade, and the modified Fisher score on admission and occurrence of DCI in aSAH patients. Preliminary evidence of this study suggests that early high CSF glutamate levels are correlated with DCI in aSAH patients.

Figure 1

CSF samples of control and aSAH patients were collected within 48 h. The glutamate concentration in CSF was measured using the Glutamate Assay Kit and expressed as μmol/L. (A) Box and whisker plot of early CSF levels of glutamate in patients with normal pressure hydrocephalus (control, n = 8) and aSAH patients (n = 61), unpaired two-tailed t-test, p < 0.001. (B) Box and whisker plot of early CSF levels of glutamate in control patients (n = 8), aSAH patients without DCI (n = 42) or with DCI (n = 19), one-way analysis of variance (ANOVA) followed by Bonferroni’s multiple comparison test, ^***p < 0.001.

Figure 2

CSF samples of aSAH patients were collected within 48 h. The glutamate concentration in CSF was measured using the Glutamate Assay Kit and expressed as μmol/L. (A) Scatter dot plot of early CSF levels of glutamate in aSAH patients who had a Hunt and Hess grade 1–3 (n = 44) or 4–5 (n = 17), (B) WFNS grade I–III (n = 46) or IV–V (n = 15), and (C) modified Fisher score 1–2 (n = 42) or 3–4 (n = 19), unpaired two-tailed t-test, p < 0.001.