Zimmerman R A, Bilaniuk L T, Gallo E
AJR Am J Roentgenol. 1978 Mar;130(3):503-6. doi: 10.2214/ajr.130.3.503.
A dilated fourth ventricle due to outlet obstruction is a clinical-radiologic entity with symptoms similar to those of a posterior fossa space-occupying lesion. Computed tomography reveals cystic dilatation of the fourth ventricle and hydrocephalus supratentorially. Frequently the symptoms resolve completely and the fourth ventricle returns to normal following lateral ventricular shunting. If there is actual obliteration of the aqueduct, the fourth ventricle must be shunted directly. While the exact mechanism by which the fourth ventricle becomes trapped is not fully known, outlet obstruction must be present. It is most frequently related to previous episodes of meningitis or subarachnoid hemorrhage. In a review of 48 cases of an abnormally enlarged fourth ventricle demonstrated on CT, six were found to have a trapped fourth ventricle. Careful attention to densities and configurations on CT allows its differentiation from other lesions such as cystic tumors and cysts.
由于出口梗阻导致的第四脑室扩张是一种临床-放射学实体，其症状与后颅窝占位性病变相似。计算机断层扫描显示第四脑室囊性扩张及幕上脑积水。通常，症状会完全缓解，侧脑室分流术后第四脑室会恢复正常。如果导水管确实闭塞，则必须直接对第四脑室进行分流。虽然第四脑室被困的确切机制尚不完全清楚，但必须存在出口梗阻。它最常与既往脑膜炎或蛛网膜下腔出血发作有关。在对CT显示的48例第四脑室异常扩大病例的回顾中，发现6例存在被困第四脑室。仔细观察CT上的密度和形态有助于将其与其他病变如囊性肿瘤和囊肿区分开来。
