What is Your Diagnosis

Meningocele: The embryological development of the neural axis is rather complex, hence congenital disorders are not uncommon. A meningocele is an outpouching of the meninges, mostly dorsally (Fig. 11.46a). If it also contains brain parenchyma, it is called a myelomeningocele.

Dandy-Walker complex: In Dandy-Walker complex, aplasia of the cerebellar vermis goes along with cystic dilatation of the fourth ventricle (Fig. 11.46b). The posterior fossa is enlarged, the tentorium is raised. Resulting compromised CSF flow is frequently associated with hydrocephalus.

Arnold-Chiari malformations: The Arnold-Chiari I malformation is a complex group of malformations characterized by the downward displacement of the cerebellar tonsils and the medulla oblongata into the cervical spinal canal (Fig. 11.46c). Arnold-Chiari II malformations are more complex and include spinal dysraphism and menin-goceles or myelomeningoceles.

I The Case of Jimmy Slowly r%

Fig. 11.45 Can you determine Jimmy's histological diagnosis on the basis of these representative images?

I Congenital Malformations of the Brain a Meningocele b Dandy-Walker complex c Arnold-Chiari malformation a Meningocele b Dandy-Walker complex c Arnold-Chiari malformation

Dandy Walker Brain Images
d Agenesis of the corpus callosum
Pachygyria Picture

e Pachygyria f Tuberous sclerosis g Venous angioma e Pachygyria f Tuberous sclerosis g Venous angioma

Spinal Dysraphism

Fig. 11.46a This meningocele presents itself as a dorsal outpouching of the dura through an osseous defect. The dural pouch is filled with CSF. b On this axial CT image the vermis is missing, the fourth ventricle is enlarged, and the temporal horns are dilated considerably, indicative of hydrocephalus. This is a patient with Dandy-Walker complex. c Descent of cerebellum and brainstem into the spinal canal is characteristic of the Arnold-Chiari malformation. There is also an associated malformation of the osseous craniocervical junction zone. d The corpus callosum is missing completely (arrow, left image) on this coronal MR image (compare the normal anatomy in Fig. 11.32b). Agenesis of the corpus callosum leads to a club-shaped dilata

Fig. 11.46a This meningocele presents itself as a dorsal outpouching of the dura through an osseous defect. The dural pouch is filled with CSF. b On this axial CT image the vermis is missing, the fourth ventricle is enlarged, and the temporal horns are dilated considerably, indicative of hydrocephalus. This is a patient with Dandy-Walker complex. c Descent of cerebellum and brainstem into the spinal canal is characteristic of the Arnold-Chiari malformation. There is also an associated malformation of the osseous craniocervical junction zone. d The corpus callosum is missing completely (arrow, left image) on this coronal MR image (compare the normal anatomy in Fig. 11.32b). Agenesis of the corpus callosum leads to a club-shaped dilata tion of the posterior horns of the lateral ventricles (right image). e This 1-year-old, severely retarded child has extremely thickened and coarse-appearing gyri. This configuration is termed pachygyria. Compare to the normal gyri in Fig. 11.1a. The child also suffered from corpus callosum agenesis that caused the club-shaped dilatation of the posterior horns. f Tuberous sclerosis is characterized by the formation of tubers (nodules) alongside the ventricular wall (subependymally), which may calcify (arrow). g This median sagittal MR image, which was obtained after contrast administration, displays an atypically thick centripetal vein (arrow). This is a textbook case of a venous angioma.

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