Peter S Stewart, Bindi S Brook, Oliver E Jensen, Tamsin A Spelman, Robert J Whittaker, Moussa A Zouache
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引用次数: 0
Abstract
Purpose: Subdural hemorrhage along the optic nerve (ON) is a histopathological indicator of abusive head trauma (AHT) in infants. We sought to determine if this bleeding could be caused by an abrupt increase in intracranial pressure transmitted to cerebrospinal fluid (CSF) at the optic foramen (OF).
Methods: A theoretical model is developed to simulate the effect of a pressure perturbation of maximal amplitude P applied at the optic foramen for a short duration T on the CSF-filled ON subarachnoid space (ONSAS). The ONSAS is modelled as a fluid-filled channel with an elastic wall representing the flexible ONSAS-arachnoid/dura interface. A constitutive law describing the relationship between CSF pressure and ONSAS deformation is inferred from published measurements. CSF pressure profiles along the ONSAS are examined systematically over a broad range of P and T.
Results: The pressure perturbation initiated at the OF produces a pressure wave that stretches the ONSAS. This wave propagates rapidly along the ONSAS toward the scleral end of the ON, where it is reflected back toward the brain. For sufficiently small T a shock wave with amplification up to six times larger than P over a timescale of tens of milliseconds is observed at the scleral end of the ON. Comparatively smaller amplifications are observed for slower perturbations.
Conclusions: A sudden increase in CSF pressure in the cranial cavity can cause a rapid expansion of the ONSAS, which may lead to rupture of the bridging blood vessels. Our study predicts a plausible mechanism for subdural hemorrhage that occurs in abusive head trauma in infants.
目的:沿视神经(ON)硬膜下出血是婴儿头部外伤(AHT)的一个组织病理学指标。我们试图确定这种出血是否会因颅内压突然升高传导至视神经孔(OF)处的脑脊液(CSF)而引起:方法:建立了一个理论模型,模拟在视神经孔处施加最大振幅为 P 的压力扰动,持续时间为 T,对充满 CSF 的ON蛛网膜下腔(ONSAS)的影响。ONSAS被模拟为一个充满液体的通道,其弹性壁代表灵活的ONSAS-蛛网膜/硬脑膜界面。根据已发表的测量结果推断出描述 CSF 压力与 ONSAS 变形之间关系的构成法则。在广泛的 P 和 T 范围内,系统地研究了沿 ONSAS 的 CSF 压力曲线:结果:从 OF 开始的压力扰动产生了压力波,拉伸了 ONSAS。这种波沿着 ONSAS 向 ON 的巩膜端快速传播,在那里被反射回大脑。当 T 足够小时,在 ON 的巩膜端观察到的冲击波在数十毫秒的时间尺度上放大到 P 的六倍。在较慢的扰动下观察到的振幅相对较小:结论:颅腔内 CSF 压力的突然增加会导致 ONSAS 快速扩张,从而导致桥接血管破裂。我们的研究预测了婴儿头部外伤时发生硬膜下出血的合理机制。
期刊介绍:
Investigative Ophthalmology & Visual Science (IOVS), published as ready online, is a peer-reviewed academic journal of the Association for Research in Vision and Ophthalmology (ARVO). IOVS features original research, mostly pertaining to clinical and laboratory ophthalmology and vision research in general.