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Updated: Dec 27, 2025
A Low Mortality Rat Model to Assess Delayed Cerebral Vasospasm After Experimental Subarachnoid Hemorrhage
Published on: January 17, 2013
The ESAS-score: A histological severity grading system of subarachnoid hemorrhage using the modified double
Dorothee Mielke1, Kim Bleuel2, Christine Stadelmann2
1Department of Neurosurgery, Georg-August-University Göttingen, Göttingen, Germany.
Objective:
The amount of extravasated blood is an established surrogate marker for subarachnoid hemorrhage (SAH) severity, which varies in different experimental SAH (eSAH) models. A comprehensive eSAH grading system would allow a more reliable correlation of outcome parameters with SAH severity. The aim of this study was to define a severity score for eSAH related to the Fisher-Score in humans.
Material And Methods:
SAH was induced in 135 male rats using the modified double hemorrhage model. A sham group included 8 rats, in which saline solution instead of blood was injected. Histological analysis with HE(hematoxylin-eosin)-staining for the visualization of blood was performed in all rats on day 5. The amount and distribution of blood within the subarachnoid space and ventricles (IVH) was analyzed.
Results:
The mortality rate was 49.6% (71/143). In all except five SAH rats, blood was visible within the subarachnoid space. As expected, no blood was detected in the sham group. The following eSAH severity score was established (ESAS-score): grade I: no SAH visible; grade II: local or diffuse thin SAH, no IVH; grade III: diffuse / thick layers of blood, no IVH; grade IV: additional IVH. Grade I was seen in five rats (7.9%), grade II in 28.6% (18/63), grade III in 41.3% (26/63) and grade IV in 22.2% (14/63) of the rats with eSAH.
Conclusion:
The double hemorrhage model allows the induction of a high grade SAH in more than 60% of the rats, making it suitable for the evaluation of outcome parameters in severe SAH.
