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Disorders of Ocular Motility 1

Topic: Behavior

Created on Sunday, August 27 2006 by jdmiles

Last modified on Sunday, September 17 2006.

A 499 year-old female presents with recent abrupt onset of abnormal eye movements. On exam, you see the movements shown in the image above as she follows your finger to the left and right. Of the following options, which is the most likely site of the lesion?

 
        A) Left cranial nerve VI
 
        B) Bilateral medial longitudinal fasciculi
 
        C) Right cranial nerve VI
 
        D) Left medial longitudinal fasciculus
 
        E) Right medial longitudinal fasciculus
 

 


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This question was created on August 27, 2006 by jdmiles.
This question was last modified on September 17, 2006.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ANSWERS AND EXPLANATIONS




A) Left cranial nerve VI

This answer is incorrect.


A lesion affecting the abducens nerve (CN VI) would result in impaired abduction of the eye ipsilateral to the lesion. This patient has intact abduction of the left eye.   (See References)

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B) Bilateral medial longitudinal fasciculi

This answer is incorrect.


A lesion affecting both medial longitudinal fasciculi would present as bilateral impaired adduction, with nystagmus of either eye when it is abducted.   (See References)

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C) Right cranial nerve VI

This answer is incorrect.


A lesion affecting the abducens nerve (CN VI) would result in impaired abduction of the eye ipsilateral to the lesion. This patient has impaired adduction of the right eye, with normal abduction.   (See References)

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D) Left medial longitudinal fasciculus

This answer is incorrect.


A lesion of the left medial longitudinal fasciculus would present as impaired adduction of the left eye, with nystagmus in the right eye when it is abducted.   (See References)

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E) Right medial longitudinal fasciculus

This answer is correct.


This patient has impaired adduction of the right eye, with some nystagmus of the left eye on abduction during attempted conjugate horizontal eye movements. This constellation of findings defines an internuclear ophthalmoplegia (INO). An INO localizes to a lesion of the medial longitudinal fasciculus (MLF) ipsilateral to the eye with the adduction deficit.   (See References)

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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. Pp. 289.
2. Wall, M. (2004). Brainstem Syndromes. In In Bradley, W.G., Daroff, R.B., Fenichel, G.M., and Jankovic, J. (Eds.). Neurology in Clinical Practice, 4th Edition. Butterworth Heinemann, Philadelphia. Pp. 273-286.
3. Leigh, R.J., and Zee, D.S. (2006). The Neurology of Eye Movements, 4th Edition. Oxford University Press, Oxford.
4. Bickley, L.S., and Hoekelman, R.A. (1999). Bates' Guide to Physical Examination and History taking, 7th Edition. Lippincott, Philadelphia. Pp. 163-244.
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behavior
Disorders of Ocular Motility 1
Question ID: 827200601
Question written by J. Douglas Miles, (C) 2006-2009, all rights reserved.
Created: 08/27/2006
Modified: 09/17/2006
Estimated Permutations: 2880

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