Shankar Jai Jai Shiva, Chakraborty Santanu, Lum Cheemun
Department of Diagnostic Imaging, The Ottawa Hospital, Ottawa, ON, Canada.
Neuroradiology. 2009 Jul;51(7):453-6. doi: 10.1007/s00234-009-0518-7. Epub 2009 Mar 21.
In patients with Intracranial Hypotension Syndrome (IHS), we observed reduction of the angle between vein of the Galen (VOG) and internal cerebral vein (ICV), which returns to the baseline after treatment. We coin the term "venous hinge" to describe this dynamic process and discuss its importance in IHS.
A midsagittal T1W image showing both VOG and ICV in the same plane was retrospectively analyzed by three different neuroradiologists in 17 patients with IHS. The angle between the lines drawn along the main axis of VOG and ICV (venous hinge angle (VHA)) was measured and documented. This angle measured from the magnetic resonance imaging (MRI) of the 50 normal controls was also recorded. Paired t tests were used to compare the VHA between male and female controls and between patients of IHS and normal controls. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were calculated. The VHA was also calculated after treatment of these patients and paired t test was done to look for significant change in the VHA after treatment.
The mean VHA formed by the veins in the IHS and control groups were 65 degrees (35-98 degrees) and 91 degrees (76-124 degrees) respectively (P < 0.0001). At a VHA of 79 degrees, the sensitivity, specificity, PPV, and NPV for diagnosis of IHS were 88.24%, 92%, 78.95%, and 95.83% respectively. In ten patients, follow-up MRI demonstrated normalization of the collapsing angle following appropriate treatment (p = 0.003).
We report a previously undescribed imaging finding in patients with IHS. Recognition of this sign may aid in the diagnosis of IHS.
在颅内低压综合征（IHS）患者中，我们观察到大脑大静脉（VOG）与大脑内静脉（ICV）之间的夹角减小，治疗后该夹角恢复至基线水平。我们创造了“静脉铰链”这一术语来描述这一动态过程，并讨论其在IHS中的重要性。
由三位不同的神经放射科医生对17例IHS患者的矢状面T1加权图像进行回顾性分析，该图像在同一平面显示了VOG和ICV。测量并记录沿VOG和ICV主轴绘制的线之间的夹角（静脉铰链角（VHA））。还记录了从50名正常对照者的磁共振成像（MRI）中测得的该夹角。采用配对t检验比较男性和女性对照者之间以及IHS患者与正常对照者之间的VHA。计算敏感性、特异性、阳性预测值（PPV）和阴性预测值（NPV）。对这些患者进行治疗后也计算VHA，并进行配对t检验以观察治疗后VHA的显著变化。
IHS组和对照组静脉形成的平均VHA分别为65度（35 - 98度）和91度（76 - 124度）（P < 0.0001）。在VHA为79度时，诊断IHS的敏感性、特异性、PPV和NPV分别为88.24%、92%、78.95%和95.83%。在10例患者中，随访MRI显示经过适当治疗后塌陷角恢复正常（p = 0.003）。
我们报告了IHS患者中一种先前未描述的影像学表现。识别这一征象可能有助于IHS的诊断。
