Article
Grading of experimental subarachnoid hemorrhage – definition of a SAH severity score
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Published: | June 9, 2017 |
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Objective: Animal models are essential for the research on pathophysiological processes following subarachnoid hemorrhage (SAH). The amount of extravasated blood is an established surrogate marker for the SAH severity, which varies comparing different experimental SAH models. A comprehensive grading system of experimental SAH (eSAH) would allow a more reliable correlation of outcome parameters with the SAH severity and a better comparability of experimental SAH models. The aim of this study was to define a severity score for eSAH.
Methods: SAH was induced in 31 Sprague Dawley male rats using the double hemorrhage model. A sham group included 5 rats, in which saline solution instead of autologous arterial blood was injected. After perfusion-fixation a histological analysis with HE(hematoxylin-eosin)-staining for visualization of blood was performed in all rats. The amount and distribution of blood within the subarachnoid space and ventricular system were analyzed.
Results: In all SAH rats blood was visible within the subarachnoid space. As expected, no blood was visible in the sham group. The following severity score was defined: 0 = no visible blood, 1 = local small amount of blood, 2 = diffuse small amount of blood, 3 = diffuse high amount of blood and 4 = additional intraventricular hemorrhage. Grade 1 SAH was detected in 4% (1/31), grade 2 SAH in 10% (3/31), grade 3 SAH in 23% (7/31) and grade 4 SAH in 63% (20/31) of the rats with SAH.
Conclusion: The double hemorrhage model allows the induction of a high grade SAH, subsequently making it especially suitable for evaluation of outcome parameters in severe SAH. We recommend a validation of the SAH severity score in other experimental SAH models.