Department of Neuroradiology, Institute of Neurosurgery Dr. Asenjo, National Health Service, Santiago, Chile.
Fetal Imaging Unit, FETALMED-Maternal-Fetal Diagnostic Center, Santiago, Chile.
Prenat Diagn. 2021 Jul;41(8):942-948. doi: 10.1002/pd.5905. Epub 2021 Feb 5.
To investigate the role of the interpeduncular angle (IPA) as a new indicator of intracranial hypotension in fetuses with open spinal dysraphism (SD).
Two groups of fetuses undergoing magnetic resonance imaging (MRI) examination were identified. The study group included fetuses with open SD (n = 21), while the control group included fetuses with a normal brain and spine (n = 43). Two observers retrospectively evaluated axial T2-weighted images of the brain and the IPA was identified and measured. Other features of the Chiari II malformation were also evaluated in the study group and correlated with the IPA.
The average value (±SD) of the IPA for the study and control groups was 9.8° ± 18.5° and 60.2° ± 5.9°, respectively. The intergroup analysis of the IPA measurements revealed a statistically significant difference between the groups (p < 0.005). Brainstem slumping or cerebellar tonsillar descent, collapse of the fourth ventricle, and ventriculomegaly also had a significant correlation with a lower IPA (p = 0.001).
Measuring the IPA may be a useful technique for assessing the degree of intracranial hypotension in fetuses with open SD. This technique can also detect less severe cases of prenatal intracranial hypotension, even before cerebellar tonsillar descent. The lower IPA in fetuses with open SD further supports the theory that cerebrospinal fluid leakage, and not traction, is the underlying cause of Chiari II malformation.
探讨脚间窝角（IPA）作为开放性脊柱裂（SD）胎儿颅内低血压的新指标的作用。
确定了两组接受磁共振成像（MRI）检查的胎儿。研究组包括开放性 SD 胎儿（n=21），对照组包括脑和脊柱正常的胎儿（n=43）。两名观察者回顾性评估脑的轴位 T2 加权图像，并确定和测量 IPA。还在研究组中评估 Chiari II 畸形的其他特征，并与 IPA 相关联。
研究组和对照组的 IPA 平均值（±SD）分别为 9.8°±18.5°和 60.2°±5.9°。IPA 测量的组间分析显示两组之间存在统计学显著差异（p<0.005）。脑干下垂或小脑扁桃体下降、第四脑室塌陷和脑室扩大也与较低的 IPA 有显著相关性（p=0.001）。
测量 IPA 可能是评估开放性 SD 胎儿颅内低血压程度的有用技术。该技术还可以检测到更轻微的产前颅内低血压病例，甚至在小脑扁桃体下降之前。开放性 SD 胎儿较低的 IPA 进一步支持脑脊液漏而非牵引是 Chiari II 畸形的根本原因的理论。
