Department of Radiology and Biomedical Imaging, University of California, San Francisco, 505 Parnassus Ave, Box 0628, Room L-358, San Francisco, CA 94143-0628, USA.
Radiographics. 2011 Nov-Dec;31(7):1889-905. doi: 10.1148/rg.317115083.
The third ventricle lies in the center of the brain. It is surrounded by critical nuclear structures (the hypothalamus and thalami) and important glandular structures (the pituitary and pineal glands). Although a wide array of pathologic processes may involve the third ventricle, most are extrinsic masses. By understanding the anatomic boundaries of the third ventricle and its relationship to adjacent structures, it is possible to create short lists of differential diagnoses. Third ventricle masses can be classified as arising in or immediately adjacent to one of five locations: anterior, posterior, inferior, foramen of Monro, and intraventricular. Anterior masses involve the optic and infundibular recesses, posterior masses affect or arise in the posterior commissure and pineal gland, and inferior masses involve or affect the ventricle floor. Masses may also arise at or adjacent to the foramen of Monro or entirely within the third ventricle. Of the intraventricular masses, chordoid glioma-a rare low-grade primary neoplasm-is unique to the third ventricle. Congenital malformations of the third ventricle are uncommon and are most often noted during childhood. Most commonly, these anomalies represent malformations of the neurohypophysis, which may manifest as hormonal abnormalities, or stenosis of the aqueduct of Sylvius, which manifests as dilatation of the third and lateral ventricles (hydrocephalus).
第三脑室位于大脑的中心。它被关键的核结构（下丘脑和丘脑）和重要的腺体结构（垂体和松果体）包围。虽然许多病理过程可能涉及第三脑室，但大多数都是外部肿块。通过了解第三脑室的解剖边界及其与邻近结构的关系，可以列出一系列可能的鉴别诊断。第三脑室的肿块可以分为五类：前、后、下、Monro 孔和脑室内部。前颅窝肿块累及视交叉和漏斗隐窝，后颅窝肿块影响或起源于后联合和松果体，下颅窝肿块累及或影响脑室底部。肿块也可能发生在 Monro 孔或完全在第三脑室。在脑室内部肿块中，脊索样胶质瘤是一种罕见的低级原发性肿瘤，是第三脑室特有的。第三脑室的先天性畸形并不常见，多在儿童时期发现。这些异常最常见的是神经垂体的畸形，可能表现为激素异常，或 Sylvius 导水管狭窄，表现为第三脑室和侧脑室扩张（脑积水）。
