Intracranial pressure changes and outcomes in the early phase of experimental subarachnoid hemorrhage: severity of subarachnoid hemorrhage and maximum intracranial pressure

Purpose To investigate the correlation between intracranial pressure (ICP) and the outcomes in rat subarachnoid hemorrhage (SAH) model and determine whether maximum ICP can predict severity of SAH. Methods Sprague-Dawley rats underwent the monofilament puncture procedure to induce SAH, and were divided into 4 groups according to the maximum ICP for survival prediction: sham group, mild ICP group (ICP < 50 mmHg), moderate ICP group (ICP 50–149 mmHg), and severe ICP group (ICP ≥ 150 mmHg). Results Maximum ICP showed strong correlations with the neurological score, SAH grade at 24 hours after induction, and mortality. Histological study demonstrated that greater increase in maximum ICP was associated with worse outcome and more severe neuronal damage, apoptosis, and oxidative stress in the brain cortex and hippocampus at 24 hours after induction. Conclusion The present study demonstrates that monitoring the ICP can confirm the induction of SAH and classify individual cases into severity grade. Animals with maximum ICP of 50–149 mmHg may be the most suitable for the experimental study of SAH.