一滴水 发表于 2012-4-23 11:56:33

胼胝体发育不良(Corpus Callosum Agenesis)MRI病例

C A S E 1 病例1
1. Summarize all imaging findings seen on this neonatal magnetic resonance image (MRI).
2. What is your diagnosis?
3. In which order does the corpus callosum (CC) develop?
4. In which malformation is the posterior CC developed without an anterior part?
4. 在什么畸形中,胼胝体仅后部发育正常而前部缺如?

一滴水 发表于 2012-4-23 11:57:00

本帖最后由 一滴水 于 2012-4-23 11:58

A N S W E R S答案
C A S E 1病例1
Diagnosis: Corpus Callosum Agenesis

1. Complete lack of the CC, radiating appearance of the medial brain sulci, no inversion of the cingulated gyrus, trident shape of the ventricles on coronal imaging, malrotated hippocampi, high-riding third ventricle, prominent adhesion interthalamica, colpocephaly, parallel course of the lateral ventricles on axial images, Probst bundle (tractography) that runs in the anteroposterior (AP) direction without left-right crossing, mild ventriculomegaly.
2. Complete agenesis of the CC.
3. Genu, truncus, splenium, and rostrum.
4. Lobar and semilobar holoprosencephaly.

Hetts SW, et al: Anomalies of the corpus callosum: an MR analysis of the phenotypic spectrum of associated malformations, AJR Am J Roentgenol 187:3–8, 2006.

Blickman JG, Parker BR, Barnes PD: Pediatric radiology— the requisites, ed 3, Philadelphia, 2009, Mosby, p 222.

The CC is the largest commissure (bundle of white matter tracts) connecting both cerebral hemispheres. Additional hemispheric connections are the anterior commissure and the hippocampal commissure. The CC has a complex, programmed anterior-to-posterior development starting with the genu and followed by the truncus and splenium. The rostrum of the CC is the final segment to develop. 胼胝体是连接双侧大脑半球的最大的联合纤维组织(白质纤维束)。其它的半球连接包括前联合和海马联合。胼胝体按照从前向后的顺序发育,先是膝部,然后是体部和压部,最后是嘴部。Agenesis of the CC is observed on imaging with multiple, characteristic anatomic sequelae. Most of the classical sequelae are demonstrated in this case. The lack of the CC is usually evident in the midline, sagittal slice. In addition, the sulci along the medial surface of both cerebral hemispheres show a typical radiating appearance converging to the third ventricle. The third ventricle may be enlarged and extend interhemispherically. In rare cases the third ventricle may reach the vertex, or an associated interhemispheric cyst may be revealed影像学检查可见胼胝体发育不良的多个特征性的解剖学改变,大部分可见于本例。胼胝体缺如常于中线矢状位图像清楚显示。另外,双侧大脑半球内侧面的脑沟呈典型的放射状,汇聚于第三脑室。第三脑室可扩大,上凸至双侧大脑半球之间,极个别病例的第三脑室甚至可达颅顶,或伴有半球间囊肿。On axial imaging the lateral ventricles reveal a parallel course because the CC is lacking. In addition, frequently the occipital horns of the ventricles are enlarged (colpocephaly). The fibers that cannot cross the midline usually realign along the medial contour of the lateral ventricles and run in an anterior-to-posterior direction. These fibers are known as Probst bundles and can easily be recognized on tractography reconstructions using diffusion tensor imaging data. On coronal imaging the combination of the separated lateral ventricles, the medial impression of these ventricles by the Probst bundles, and the shape of the adjacent third ventricle mimic a trident or Texas longhorn cow.由于胼胝体缺如,轴位像可见双侧侧脑室呈平行走行。另外,常见双侧侧脑室枕角扩大。未能跨越中线的大脑纤维束常沿侧脑室内缘重新排列,呈前后走行,称为Probst束。采用扩散张量成像数据行神经纤维束成像,可清楚显示Probst束。冠状位可见分离的、受Probst束压迫内缘的双侧侧脑室和邻近的第三脑室共同构成三叉戟状或呈德克萨斯长角牛状。Because the CC is one part of the commissures connecting both hemispheres, the remainder of the commissures should be studied for additional malformations. The hippocampi may be malrotated; the anterior commissure may be lacking. In 50% of children a CC agenesis is part of a more extensive malformation (e.g., Dandy-Walker malformation, Arnold-Chiari II malformation, septooptic dysplasia). In addition, migrational abnormalities are frequently encountered. Ruling out additional malformations is essential; doing so will determine a functional and cognitive prognosis由于胼胝体只是双侧半球间连接的一部分,还须观察半球间连接的其它部分有无合并畸形。海马可能旋转不良,前联合可能缺如。在50%的患儿中,胼胝体发育不良只是更复杂的畸形(如Dandy-Walker畸形,Arnold-Chiari II畸形,视隔发育不良)的一部分。另外,常见神经元移行异常。除外合并畸形非常重要,因为这样可确定患儿的功能和认知方面飞预后。Clinically, an isolated CC agenesis may be an incidental finding on an MRI. If additional malformations are present, then seizures, a developmental delay, and a hypothalamic- pituitary dysfunction may result. CC agenesis should be differentiated from secondary injury of the CC. For example, a severe atrophy of the CC resulting from an extensive periventricular leukomalacia should not be confused with a primary CC agenesis. In addition, it is important to remember that the only exception to the anterior-to-posterior rule of development is a semilobar or lobar holoprosencephaly. In these malformations the posterior CC may be present without the genu or anterior trunk of the CC.临床上,单纯性胼胝体发育不良可能只是被MR偶然发现的。如合并其它畸形,则可能出现癫痫发作、发育延迟(精神发育迟滞?)、下丘脑-垂体功能低下等临床表现。胼胝体发育不良须与胼胝体的继发性损伤(例如,由于脑室周围白质软化导致的严重胼胝体萎缩)相鉴别。另外,须牢记,大脑发育按由前往后顺序进行的唯一的例外是全脑叶型和半脑叶型全脑无裂畸形,在这些畸形中,胼胝体后部可存在,而胼胝体膝部或体部前方缺如。

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lmshu9 发表于 2014-8-18 16:37:36

学习了! 谢谢了!
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