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Another Arnold!

Topic: Pediatric

Created on Saturday, November 8 2008 by rednucleus

Last modified on Saturday, November 8 2008.

A child has been referred to you as having Arnold-Chiari malformation type II. The presence of which one of the following would suggest type I, not type II malformation?

A) Normal brain

B) Inferiorly displaced cerebellum

C) Beaked tectum

D) Inter-digitated gyri

E) Medullary kink

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This question was created on November 08, 2008 by rednucleus.
This question was last modified on November 08, 2008.

ANSWERS AND EXPLANATIONS

A) Normal brain

This answer is correct.

Grossly normal brain is compatible with type I, not type II, malformation. Type II malformation may demonstrate medullary kink, beaked tectum, inter-digitated gyri, and inferiorly displaced vermis, and that their cerebellum seems to creep around the brainstem. (See References)


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B) Inferiorly displaced cerebellum

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C) Beaked tectum

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D) Inter-digitated gyri

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E) Medullary kink

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References:

1. Victor, M., and Ropper, A.H. (2001). Adams and Victor's Principles of Neurology, 7th Edition. McGraw-Hill, New York. (ISBN:0070674973)

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pediatric
Another Arnold!
Question ID: 110808114
Question written by rednucleus. (C) FrontalCortex.com 2006-2009, all rights reserved. Created: 11/08/2008
Modified: 11/08/2008
Estimated Permutations: 120

User Comments About This Question:

1 user entries

jdmiles

pediatric Comment Nov 09, 2008 @ 10:55

Thanks to rednucleus for this well-thought out question.

I did want to point out to the reader that, while a normal brain is more suggestive of a type I Chiari malformation, a type I Chiari does not guarantee a normal brain.

There were 4 types of malformations described by Hans Chiari that we now refer to as Chiari malformations. Chiari I is a protrusion of part of the cerebellar tonsils through the foramen magnum. In Chiari II, there is a Chiari I plus downward displacement of the medulla and 4th ventricle. A Chiari III malformation is defined as cervical spina bifida with a cerebellar encephalocele. The Chiari IV malformation (a term now not often used) is probably unrelated, and is defined as hypoplasia of the cerebellum, and does not involve protrusion of the tonsils through the foramen magnum.

Syringomyelia, syringobulbia, and hydrocephalus are often seen in each of the Chiari I, II and III malformations. Patients with a Chiari II malformation almost always have a lumbar meningomyelocele.

Note that the definition of Chiari malformations may depend on the source you read. Adams & Victor (8th edition) defines the Chiari I and II as "the cerebellomedullary malformation without and with a meningomyelocele, respectively."

Thanks again to rednucleus for another good question.

REFERENCES:

1. Sklar, E.M.L., Ruiz, A., Quencer, R.M., and Falcone, S.F. (2004). Structural neuroimaging. In Bradley, W.G., Daroff, R.B., Fenichel, G.M., and Jankovic, J. (Eds.). Neurology in Clinical Practice, Fourth Edition. Butterworth Heinemann, Philadelphia, pp. 521-597 (ISBN:0750674695).

2. Sarnat, H.B., and Flores-Sarnat, L. (2004). Developmental disorders of the nervous system. In Bradley, W.G., Daroff, R.B., Fenichel, G.M., and Jankovic, J. (Eds.). Neurology in Clinical Practice, Fourth Edition. Butterworth Heinemann, Philadelphia, pp. 1763-1789 (ISBN:0750674695).

3. Rosenbaum, R.B., and Ciaverella, D.P. (2004). Disorders of bones, joints, ligaments, and meninges. In Bradley, W.G., Daroff, R.B., Fenichel, G.M., and Jankovic, J. (Eds.). Neurology in Clinical Practice, Fourth Edition. Butterworth Heinemann, Philadelphia, pp. 2189-2222 (ISBN:0750674695).

4. Victor, M., and Ropper, A.H. (2005). Adams and Victor's Principles of Neurology, 8th Edition. McGraw-Hill, New York. P. 861. (ISBN:007141620X)

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