need help with your account or subscription? click here to email us (or see the contact page)
join telegramNEW! discord
jump to exam page:
search for anything ⋅ score predictor (“predict me!”)

You must be logged in to vote!
Retired NBME 24 Answers

nbme24/Block 2/Question#18 (reveal difficulty score)
A 68-year-old man has loss of pain and ...
Right dorsolateral medulla 🔍 / 📺 / 🌳 / 📖
tags: FA20p504

 Login (or register) to see more


 +26  upvote downvote
submitted by m-ice(370)
get full access to all contentpick a username

The patient has loss of pain and temperature on the right side of his face. Sensation of the face is ipsilateral, so the issue must be on the patient's right side, which we can confirm by knowing that sensation of the body is contralateral, and he has lost left sided pain and temperature of the body.

Pain and temperature sensation of the body is part of the spinothalamic tract, which always runs laterally through the brainstem. This can be confirmed by remembering that sensation to the face also runs laterally through the brainstem. So, we can confirm this is a right sided lateral brainstem issue.

The loss of gag reflex and paralysis of the vocal cords imply impairment of cranial nerves IX and X, both of which localize to the medulla. Therefore, the answer is right dorsolateral medulla.

get full access to all contentpick a username
duat98  You're a good man. +6
charcot_bouchard  You must be handsome too +14
amy  The dorsal vs ventral is confusing! +


You must be logged in to vote!

 +5  upvote downvote
submitted by brethren_md(105)
get full access to all contentpick a username

Lateral Medullary Syndrome (Wallenberg) - see FA for more details. Symptoms for this syndrome match up with what is being presented.

get full access to all contentpick a username


You must be logged in to vote!

 +5  upvote downvote
submitted by cassdawg(1780)
get full access to all contentpick a username

"Simple rules of the brainstem" (credit to our anatomy gods at UofL for organizing, also this image is fucking great for visual learners):

  1. There are 4 structures always in the ‘midline‘ beginning with M
    • Motor pathway (or corticospinal tract): damage results in contralateral weakness of the arm and leg
    • Medial Lemniscus: damage results in contralateral loss of vibration and proprioception in the arm and leg
    • Medial longitudinal fasciculus: damage results in ipsilateral inter-nuclear ophthalmoplegia (failure of adduction of the ipsilateral eye towards the nose and nystagmus in the opposite eye as it looks laterally)
    • Motor nucleus and nerve: damage results in ipsilateral loss of the cranial nerve that is affected (III, IV, VI or XII)

  2. There are 4 structures to the ‘side‘ (lateral) beginning with S
    • Spinocerebellar pathway: damage results in ipsilateral ataxia of the arm and leg
    • Spinothalamic pathway: damage results in contralateral alteration of pain and temperature affecting the arm, leg and rarely the trunk
    • Sensory nucleus of CN V: damage results in ipsilateral alteration of pain and temperature on the face in the distribution of CN V (this nucleus is a long vertical structure that extends in the lateral aspect of the pons down into the medulla)
    • Sympathetic pathway: damage results in ipsilateral Horner’s syndrome, that is partial ptosis and a small pupil (miosis)

  3. The rule of CN 4’s (also found in FA2020 p504)
    • 4 cranial nerves in the medulla (IX-XII)
    • 4 in the pons (V-VIII)
    • 4 above the pons (2 in the midbrain= III, IV, 2 in the cortex= I, II)
    • The 4 motor nuclei that are in the midline are those that divide equally into 12 (except I and II), including III, IV, VI and XII (V, VII, IX and XII are in the lateral brainstem)
get full access to all contentpick a username
cassdawg  Sorry for the formatting fuck up +1
drdoom  @cassdawg best to avoid doing nested lists. website doesn't seem to like that :P better to start a “brand new” list for each little subsection kinda thing :) p.s. congrats on your MVP of the Year Award! +2
unknown001  this is the most complex picture i have seen on brain stem +

Wow can we talk about how amazing this image is? Thanks for sharing!

+/- motherhen(69)

You must be logged in to vote!

 +2  upvote downvote
submitted by charcot_bouchard(574)
get full access to all contentpick a username

I get why its lateral but dont all cranial nerve except 4 arise Ventrally? WTF they add this Dorso before lateral?

get full access to all contentpick a username
qfever  I think it's the nucleus affected in lateral medullary syndrome (instead of the nerve axons) +
nerdstewiegriffin  Because in the medulla section the nucleus is dorsal motor nucleus of X +
doctordave  They all exit the brainstem ventrally, but the nuclei can be located deep within the brainstem +


You must be logged in to vote!

 +0  upvote downvote
submitted by abhishek021196(119)
get full access to all contentpick a username

Posterior inferior cerebellar artery [PICA] supplies

  1. Lateral medulla
  2. Nucleus ambiguus (CN IX, X, XI)
  3. Vestibular nuclei
  4. Lateral spinothalamic tract, spinal trigeminal nucleus
  5. Sympathetic fibers
  6. Inferior cerebellar peduncle

Damage to PICA causes Lateral medullary (Wallenberg) syndrome.

Dysphagia, hoarseness, decreased gag reflex, hiccups. Vomiting, vertigo, nystagmus decreased pain and temperature sensation from contralateral body, ipsilateral face. Ipsilateral Horner syndrome. Ipsilateral ataxia, dysmetria.

Nucleus ambiguus effects are specific to PICA lesions.

“Don’t pick a (PICA) horse (hoarseness) that can’t eat (dysphagia).” Also supplies inferior cerebellar peduncle (part of cerebellum).

get full access to all contentpick a username


You must be logged in to vote!

 -1  upvote downvote
submitted by welpdedelp(270)
get full access to all contentpick a username

This was lateral medullar syndrome aka dorsolateral infarct of the PICA.

get full access to all contentpick a username


You must be logged in to vote!

Must-See Comments from nbme24

seagull on Intestinal mucosa
tissue creep on Ask the roommate not to smoke in the apartment
drdoom on Adenosine
seagull on Increased serum testosterone concentration
atstillisafraud on Lamins
niboonsh on Only cookies are independently associated ...
atstillisafraud on Scar formation
lamhtu on Decreased adherence
drachenx on Damage to the rectovaginal septum
drdoom on Intestinal mucosa
azibird on Coronavirus
lsmarshall on Organic acid metabolism disorder
sympathetikey on Inhalant abuse
tea-cats-biscuits on Eosinophils

search for anything NEW!