Girard N, Lasjaunias P, Taylor W
Neuroradiologie Vasculaire Diagnostique et Thérapeutique, Hôpital de Bicêtre, France.
Childs Nerv Syst. 1994 Apr;10(3):141-7. doi: 10.1007/BF00301078.
We report eight cases of vein of Galen aneurysmal malformation (VGAM) associated with a "Chiari type I malformation." In four cases magnetic resonance imaging (MRI) or computed tomography performed in the neonatal period did not demonstrate the posterior fossa anomaly, which appeared on later scans. In the other cases the MRI was performed in infancy and the anomaly was already present. We compared the venous phases of the posterior fossa angiograms and the MRI in these patients. In all eight cases, the angiograms showed a reflux in the cerebellar veins, via the petrous vein, associated with a uni- or bilateral stenosis or thrombosis of the distal posterior dural sinuses. Furthermore, in two cases the posterior fossa returned to normal on MRI following endovascular treatment, while in three cases the herniation of the cerebellar tonsils decreased after the embolization. Tonsillar prolapse becomes irreversible when the venous outlet is incapable of taking the flow even when the VGAM has been treated adequately. In eight additional cases of VGAM for which MRI and angiogram studies were available and in which stenosis or thrombosis of posterior dural sinuses was present without tonsillar prolapse, no reflux into the cerebellar veins was shown. We suggest that the posterior fossa hydrovenous congestion is a result of inadequate venous drainage and that the tonsillar descent is reversible if adequate venous drainage is reconstituted following therapeutic embolization of the fistula. Tonsillar prolapse is not a consequence of mass or raised intraventricular pressure. Our observation suggests that in some other conditions, the "Chiari I malformations" may be secondary to early hydrovenous dysfunction of the posterior fossa.
我们报告了8例与“Chiari I型畸形”相关的大脑大静脉动脉瘤样畸形（VGAM）。4例在新生儿期进行的磁共振成像（MRI）或计算机断层扫描未显示后颅窝异常，该异常在后来的扫描中出现。在其他病例中，MRI在婴儿期进行，异常已经存在。我们比较了这些患者后颅窝血管造影的静脉期和MRI。在所有8例病例中，血管造影显示小脑静脉通过岩静脉反流，伴有远端后硬脑膜窦的单侧或双侧狭窄或血栓形成。此外，2例在血管内治疗后MRI显示后颅窝恢复正常，3例在栓塞后小脑扁桃体疝减轻。当即使VGAM已得到充分治疗，静脉流出道仍无法承受血流时，扁桃体脱垂就会变得不可逆转。在另外8例有MRI和血管造影研究且存在后硬脑膜窦狭窄或血栓形成但无扁桃体脱垂的VGAM病例中，未显示小脑静脉反流。我们认为后颅窝静脉性充血是静脉引流不足的结果，并且如果在瘘管的治疗性栓塞后重建了充分的静脉引流，扁桃体下移是可逆的。扁桃体脱垂不是肿块或脑室内压力升高的结果。我们的观察表明，在其他一些情况下，“Chiari I型畸形”可能继发于后颅窝早期静脉功能障碍。
