Retired (Old) NBME form question ?

[Focused1]

http://imgur.com/BxGgmr1

A 57 year old man dies 7 bdays after sudden onset of incoordination, ataxia, a loss of sensation in the right side of his face and left side of his trunk and extremities. At autopsy lesion is in the area marked in the photo by an arrow. Which artery is involved ?

1. AICA
2. Basilar
   
3. Pontine
4. PICA
5. Sup Cerebellar

The online discussion threads are notorious for errors. I looked it up and this one wan;t discussed in the NBME 7 thread on SDN but was at other forums. Most said answer is PICA. But how does this account for the contralateral loss of sensation. It has got to involve the medial lemniscus for that. The medial lemniscus is in the medial part of the pons and medulla and the lateral part of the midbrain. If its PICA (i.e Lateral Medullary Syndrome)... It cant account for the Medial lemniscus loss.

I would really appreciate help in this question.

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[sloop]

Not every stroke victim's symptoms fit the textbooks exactly. In any case, that question gives an image pointing to the lateral medulla. The question basically asks what artery supplies the lateral medulla. it's PICA.

The image is not of the Pons, so it's not AICA, basilar or pontine. It's not of the midbrain or cerebellum, so it's not SCA. It has to be PICA.

 

[pd1112]

Also, you're tunneled in on "loss of sensation" meaning touch & trying to rationalize medial lemniscus involvement. It doesn't specify touch, so it could mean touch, pain, temp and/or proprioception. In this case, it's decreased pain/temp due to involvement of the spinothalamic tract in the anterolateral medulla.