Radiological Category Neuroradiology Principal Modality 1 MRI Principal

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Radiological Category: Neuroradiology Principal Modality (1): MRI Principal Modality (2): NONE Case Report #0054

Radiological Category: Neuroradiology Principal Modality (1): MRI Principal Modality (2): NONE Case Report #0054 Submitted by: Karen Seaberg, M. D. Faculty reviewer: Clark Sitton, M. D. Date accepted: 23 January 2004

Case History 20 year old with a history of a lumbar myelomeningocele.

Case History 20 year old with a history of a lumbar myelomeningocele.

Radiological Presentations

Radiological Presentations

Radiological Presentations

Radiological Presentations

Radiological Presentations

Radiological Presentations

Radiological Presentations

Radiological Presentations

Radiological Presentations

Radiological Presentations

Test Your Diagnosis Which one of the following is your choice for the appropriate

Test Your Diagnosis Which one of the following is your choice for the appropriate diagnosis? After your selection, go to next page. • Dandy Walker Malformation • Chiari I Malformation • Klippel-Feil Syndrome • Chiari II Malformation

Findings and Differentials Findings: Image 1: Sagital T 1 WI demonstrates elongation of the

Findings and Differentials Findings: Image 1: Sagital T 1 WI demonstrates elongation of the cerebellum and descent of the cerebellar tonsils and medulla. Additionally there is kinking of the medulla. Images 2 and 3: Axial T 2 WIs show a narrow 4 th ventricle, “beaking” of the tectum, a towering cerebellum, and a hypoplastic clivus. Images 4 and 5: Sagital T 1 and T 2 WI demonstrate dysgensis of the corpus callosum with hypoplasia of the splenium and body of the corpus callosum. Image 6: Axial T 2 WI demonstrates interdigitation of the posterior parietal lobe due to absence of the falx cerebri. Differentials: • Chiari II Malformation • Chiari I Malformation

Discussion Chairi II malformation, also known as Arnold Chiari, is a complex CNS anomaly

Discussion Chairi II malformation, also known as Arnold Chiari, is a complex CNS anomaly that occurs in 0. 02% of births with a female predominance of 2: 1. Although the exact etiology of Chairi II malformation is unknown it has been theorized that a chronic leakage of CSF in utero may lead to collapse of the developing brain resulting an abnormally small posterior fossa. In Chiari II malformation the abnormalities involving hindbrain and cerebellum are constant. These include downward displacement of the medulla and cerebellum, kinking of the medulla, anteromedial displacement of the cerebellar hemispheres as well as upward herniation of the cerebellar hemispheres and vermis through the widened incisura, and the tectal plate is often “beaked”. The ventricular system is also involved in Chiari II with 90% of patients having hydrocephalus or colpocephaly (dilation of the atria and occipital horns of the lateral ventricles). The fourth ventricle is typically small and elongated. Other associated abnormalities include agenesis of the corpus callosum, gray matter heterotopias, and lumbar myelomenigocele (seen in greater than 95% of cases).

Discussion Findings of Chiari II malformation involve the skull , dura, brain, and spine.

Discussion Findings of Chiari II malformation involve the skull , dura, brain, and spine. Changes of the skull in Chiari II can be seen on skull films, CT and MRI. Focal calvarial thinning and a “scooped-out” appearance are typical but usually resolve by the age of six months. Other skull anomalies include an abnormally small posterior fossa, enlarged foramen magnum, hypoplastic clivus, and concave petrous temporal bones. Dural abnormalities consist of a deficient tentorium producing a widened or “heart-shaped” incisura. The falx cerebri is often fenestrated or hypoplastic resulting in interdigitation of the cortical sulci.

Diagnosis 1. Chiari II Malformation References: 1. Dahnert, W. , Radiology Review Manual; 2003.

Diagnosis 1. Chiari II Malformation References: 1. Dahnert, W. , Radiology Review Manual; 2003. p 268 -270. 2. Osborn, A. , Diagnostic Radiology; 1994. pp 18 -24 3. Grossman, R. , Neuroradiology: The Requisites; 2003. pp 436 -438.