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  #1  
Old 03-20-2012
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Neuro Which cranial nerve affected first by Pituitary tumor expansion!

A 67 years old man comes to his physician because of a new onset of headaches and discharge from both nipples. An MRI of the brain shows a small tumor of the pituitary gland. If the tumor expands laterally, which of the following nerves will most likely be affected first?

A. VI
B. III
C. II
D. V
E. IV
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  #2  
Old 03-20-2012
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Cavernous sinus is located on either side of the pituitary gland.. so lateral expansion of the gland may compress 3, 4, 5, 6.. but since 6 is present within the sinus, may be it'll get compressed first.. I go with A.
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Almost didn't read lateral. So it should be CN6
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  #4  
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The answer should be the 3 cranial nerve. Most frequently affected by pituitary tumor expansion
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Sorry about this post- I keep changing my mind but I stick to CN6 because of compression internal carotid first which would compress the cn6.
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Default E) cn iv

I would've picked CN III (Occulomotor N.) But 3, 6 and 12 are also the ones that are located medially so if the question is asking LATERAL EXPANSION I would go with CN IV (Trochlear N.)
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Quote:
Originally Posted by Hope2Pass View Post
I would've picked CN III (Occulomotor N.) But 3,6 and 12 are also the ones that are located medially so if the question is asking LATERAL EXPANSION I would go with CN IV (Trochlear N.)
CN3 is directly above the CN4 in the cavernous sinus- both lateral. CN6 is posterior-lateral to the pituitary. CN12 is not in cavernous sinus.
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Its 3rd Nerve ........

The order of injury of the CNs in the cavernous sinus by lateral extension of macropituitary adenoma is CN III, CN VI, CN IV and then CN V.

Which cranial nerve affected first by Pituitary tumor expansion!-figure31.jpg
Click image to enlarge

http://www.endocrinetoday.com/view.aspx?rid=60740
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Old 03-21-2012
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think it's A.
CNVI is the nerve that runs more medial in the cavernous sinus
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CN III?

only 3 and 4 are up that high (midbrain level)
3 is the highest
so sounds good to me lol
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Definitely A
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3,4,5 and 6
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whats the ans bunny ............
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yeaaa.......ans please
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Answer is Abducens nerve CN VI
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Which cranial nerve affected first by Pituitary tumor expansion!-3427-0550x0475.jpg   Which cranial nerve affected first by Pituitary tumor expansion!-gray571.png  
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