Establishment and evaluation of a novel rat model of the fourth ventricle hemorrhage.

Background: Hemorrhagic expansion into the fourth ventricle is an independent risk factor for poor outcomes in intraventricular hemorrhage (IVH) patients. However, to date, available animal models of IVH are limited to models of supratentorial ventricular hemorrhage, and there are no specific models of fourth ventricle hemorrhage. This limitation hinders comprehensive basic research and the understanding of the pathophysiological changes that occur following fourth ventricle hemorrhage. Therefore, the development of an animal model of fourth ventricle hemorrhage is highly important.

Methods: In this study, a novel rat model of fourth ventricle hemorrhage was established via autologous blood injection through the foramen of Magendie. Anesthetized rats were positioned in a stereotaxic apparatus with their heads tilted downward at an angle of approximately 20° relative to the vertical axis. A needle was inserted through the foramen, and autologous blood obtained from the rat's heart was injected into the fourth ventricle via a microinfusion pump. Systematic evaluations of the model were conducted using small-animal magnetic resonance imaging, histopathological analysis, and neurological function assessment.

Results: The rats developed stable and reproducible fourth ventricle hematomas and ventricular dilation. They also exhibited acute-phase hydrocephalus and pathological features of perilesional brain tissue injury, with observed neurological deficits comparable to patients with fourth ventricle hemorrhage.

Conclusion: This model successfully recapitulates the clinicopathological and pathophysiological characteristics of patients with fourth ventricle hemorrhage and can be utilized for further investigation into the pathophysiological mechanisms underlying posthemorrhagic hydrocephalus and perilesional brainstem tissue injury.