Objective  To investigate the changes of serum aquaporin 4 (AQP4) and neuron specific nuclear protein (NeuN) levels in patients with delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage (aSAH) and their clinical significance.

Methods  One-hundred patients with aSAH were selected as study objects, and were divided into non-delayed cerebral ischemia group (n=68) and delayed cerebral ischemia group (n=32) according to the occurrence of delayed cerebral ischemia after aSAH. The levels of serum AQP4 and NeuN were detected by enzyme-linked immunosorbent assay (ELISA), and the correlation between serum AQP4 and NeuN was analyzed by Pearson method. The predictive value of serum AQP4 and NeuN levels for delayed cerebral ischemia after aSAH was analyzed by using the ROC curve.

Results  Compared with the non-delayed cerebral ischemia group, the proportions of patients with grade Ⅲ to Ⅳ of WFNS, those with grade Ⅲ to Ⅳ of Hunt-Hess, and serum AQP4 level in the delayed cerebral ischemia group were higher, while the serum NeuN level was lower (P < 0.05). Pearson analysis showed that serum AQP4 was negatively correlated with NeuN (P < 0.05); Logistic regression analysis showed that Hunt-Hess classification and AQP4 were risk factors for delayed cerebral ischemia after aSAH (P < 0.05), while NeuN was a protective factor of delayed cerebral ischemia after aSAH (P < 0.05). ROC curve showed that the area under the curve (AUC) of AQP4 in predicting delayed cerebral ischemia after aSAH was 0.862 (95%CI, 0.781 to 0.942), with sensitivity of 76.50%, specificity of 83.82%, and truncation of 1.19 ng/L; the AUC of NeuN in predicting delayed cerebral ischemia after aSAH was 0.771 (95%CI, 0.672 to 0.870), with sensitivity of 78.10%, specificity of 76.50%, and truncation of 0.47μg/mL; the AUC of delayed cerebral ischemia predicted by AQP4 combined with NeuN after aSAH was 0.879 (95%CI: 0.811 to 0.948), its sensitivity was 90.60% and specificity was 75.00%. The AUC value of combined diagnosis was higher than that of NeuN diagnosis alone (Z=2.476, P=0.013).

Conclusion  The serum NeuN level is down-regulated and AQP4 level is up-regulated in patients with delayed cerebral ischemia after aSAH. AQP4 combined with NeuN can be used as an evaluation index to predict delayed cerebral ischemia after aSAH.