Slowly progressive dysphagia; what CN involved? - USMLE Forums
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  #1  
Old 06-23-2011
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Neuro Slowly progressive dysphagia; what CN involved?

51-year-old male patient presents with slowly progressive dysphagia and hoarseness. The patient complains that he aspirates often while eating. Clinical testing reveals loss of the gag reflex on the right, and leftward deviation of the uvula. Careful swabbing of the back of the pharynx with a cotton swab suggests decreased sensation on the right. ENT testing reveals right vocal cord paralysis. Further neurologic testing detects some weakness in turning the head to the left against resistance, and some weakness in elevating the right shoulder against resistance. The tongue was normal, without atrophy or fasciculations, and protruded in the midline.

What cranial nerves do you think is / are involved?


A) right IX nerve
B) right X nerve
C) right XI nerve
D) right VII nerve
E) right VII, IX and XI nerves
F) right IX, X and XI nerves
G) right X and XI nerves
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  #2  
Old 06-23-2011
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My Answer..F
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  #3  
Old 06-23-2011
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Ffffffffffffffffff
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Old 06-23-2011
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Trying to decide between F and G - clearly X and XI are involved, but I'm not sure about IX.
The nasopharynx and the oropharynx are innervated by IX, and the laryngopharynx is innervated by X. In the question they say "Careful swabbing of the back of the pharynx with a cotton swab suggests decreased sensation on the right." I interpret that to mean they swabbed the laryngopharynx; if it was simply a test for IX, why would they have to go all the way to the back of the pharynx when the could simply swab the posterior third of the tongue Maybe I'm overthinking it.

I'll say G!
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Old 06-23-2011
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im thinking g as well, was thinking of the back swab in the question and also that if there was a IX lesion, surely they would have mentioned the post 1/3 tongue as well?
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Old 06-24-2011
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Correct Answer

Correct answers is F) right IX, X and XI nerves

Loss of the gag reflex on the right suggests involvement of either the right 9th (glosso pharyngeal) or 10th (vagus) nerves, or both. The paralysis of the right vocal cord suggests a right 10th nerve lesion. The decreased sensation along the pharyngeal mucosa suggests a 9th nerve lesion. Shrugging the shoulder and turning the head are functions of the trapezius and sternocleidomastoid muscles respectively. These are innervated by cranial nerve 11. Therefore, the history and physical findings strongly suggest involvement of the 9th, 10th and 11th cranial nerves.

The nuclei of the 9th and 10th nerves are in close proximity in the dorsolateral medulla, and so are often involved together. However, the nuclei of cranial nerve 11 subtending the trapezius and sternocleidomastoid muscles are actually in the cervical cord. Therefore, an intra-axial lesion would be unlikely. More likely, the lesion involves the nerves after they have exited the medulla and cervical cord and while they are traveling together. Possible locations would be in the perimedullary cistern at the level of the foramen magnum, at the level of the jugular foramen, or in the neck along the course of the carotid sheath.
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  #7  
Old 06-24-2011
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Ah, good one! Why do you think they had to swab all the way back to the pharynx for IX?
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Old 06-24-2011
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Quote:
Originally Posted by heights View Post
Ah, good one! Why do you think they had to swab all the way back to the pharynx for IX?
I think they did it because the absence of gag reflex could be due to a lesion on either one of the nerves (IX / X) or both...
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Old 06-24-2011
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bebix..those r grt questions...man...ooops...sorry,,....woman...
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Old 06-24-2011
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I think C..
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Old 06-25-2011
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Quote:
Originally Posted by mle2resident View Post
I think C..
@mle2resident, the correct answers is F) right IX, X and XI nerves (more info above)
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  #12  
Old 06-25-2011
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Ya bebix.. I got that.. Usually I answer n then scroll down to see the answer.. Very good question. Thanks.
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