NBME 22 Lateral medulla (NBME Answers)

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Retired NBME 22 Answers

nbme22/Block 2/Question#38 (reveal difficulty score)
Following a stroke, a patient is hoarse and ...
Lateral medulla 🔍 / 📺 / 🌳 / 📖
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submitted by nestlepurelife(6)

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I approached this using the Rule of 4's. Patient has hoarseness, which is a CN 10 problem. CN 10 is located in the medulla. Patient also has decreased pain/temp to her left face and right body, which suggests impairment of spinothalamic tract and sensory to CN 5. These lesions are lateral. Thus, the lesion is at the lateral medulla.

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submitted by ∗moloko270(77)

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this is Wallenberg syndrome - stroke caused by obstruction of PICA - so thats why we get symptoms of dysphagia, hoarseness, absent gag reflex (p. 502 FA)

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armymed88 dysphagia from hit of nucleus ambiguus (CN IX/X/XI) Sensation changes due to hit of lateral spinothalamic tract and spinal trigeminal Check out rule of 4s if you haven't already +2

theecohummer Yup, lateral meduallary syndrome or Wallenburg Syndrome. Whatever you want to call it. The hemifacial analgesia is from damage to the spinal trigeminal nucleus/tract, and you get the hoarseness from damage to the vagus and the body loss is from the spinal thalamic tract. You can also get Horner’s syndrome with this. +24

dr.xx Lateral medullary syndrome = Wallenberg's syndrome +

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submitted by ∗lowyield(43)

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just as an aside to what everyone saying, don't forget the 2 exceptions to the rule of 4s:

don't localize w/ CN5 (as seen here) b/c it is big and spans the pons and medulla

don't localize w/ the vestibular signs of CN8 b/c it is big. You CAN however localize with the sensoneural signs of CN8

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usmleboy This is the key to this Q! +2

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