Relationship between brain interstitial fluid tumor necrosis factor-α and cerebral vasospasm after aneurysmal subarachnoid hemorrhage

Tumor necrosis factor-α (TNF-α) has a crucial role in the onset of hemolysis-induced vascular injury and cerebral vasoconstriction. We hypothesized that TNF-α measured from brain interstitial fluid would correlate with the severity of vasospasm following aneurysmal subarachnoid hemorrhage (aSAH). From a consecutive series of 10 aSAH patients who underwent cerebral microdialysis (MD) and evaluation of vasospasm by CT angiogram (CTA) or digital subtraction angiography (DSA), TNF-α levels from MD were measured at 8-hour intervals from aSAH days 4–6 using enzyme-linked immunosorbent assay. An attending neuroradiologist blinded to the study independently evaluated each CTA and DSA and assigned a vasospasm index (VI). Five patients had a VI < 2 and 5 patients had a VI > 2, where the median VI was 2 (range 0–13). The median log TNF-α area under the curve (AUC) was 1.64 pg/mL ∗ day (interquartile range 1.48–1.71) for the VI < 2 group, and 2.11 pg/mL ∗ day (interquartile range 1.95–2.47) for the VI > 2 group (p < 0.01). Thus, in this small series of poor-grade aSAH patients, the AUC of TNF-α levels from aSAH days 4–6 correlates with the severity of radiographic vasospasm. Further analysis in a larger population is warranted based on our preliminary findings.