USMLE Step 1 Neuroanatomy Review 26 15 Midbrain (5_5)

USMLE Step 1 Neuroanatomy Review 26 15 Midbrain (5_5)

On these “Gold Standard Step 1 Facts” pages you will find Free:

  • USMLE Audio Review files from our “Gold Standard USMLE Reviews”
  • Transcriptions of those files
  • And videos (as they become available)

The idea is that you can review for the USMLE online by:

  • Listening to the Audio
  • Following along with the transcription
  • Or by watching the video (if available)

If you like what you here, you can purchase the entire Gold Standard Step 1 MP3 audio USMLE review for your iPhone, iPod, or computer here.

Let’s start our USMLE Review with Anatomy from the Gold Standard USMLE Step 1 Audio Review program.

Play USMLE Audio MP3 26 15 Midbrain (5_5) Below

Begin 26 15 Midbrain (5_5) Transcription

Now let’s take a look at the lesions of the midbrain. Student doctor,

what is the name of the syndrome that is characterized by the paralysis of upward and downward gaze, and also has light-fixed, mid-positioned pupils?

  • This is Paranaud’s syndrome. I’m kind of using the Americanization of that word, it’s actually a French word.

Now what is the other term, the more scientific term, for Paranaud’s syndrome?

  • This is also known as the dorsal midbrain syndrome.

Alright let’s review that from the other direction. What are the signs of Paranaud’s syndrome, the dorsal midbrain syndrome?

  • Paralysis of upward and downward gaze, and light-fixed, mid positioned pupils.

Student doctor, what is the most frequent cause of Paranaud’s syndrome, two different types of tumors?

  • Either a pinealoma or a germanoma.

Now in Paranaud’s syndrome, what two regions are affected?

  • The pretectal regions and the superior colliculus.

Student doctor, what is the name of the syndrome characterized by the following features: hemiplegia, weakness of the lower face, weakness of the tongue and palate, and hemiparesis of the trunk and extremities?

  • This is Weber’s syndrome. Again, this is an Americanized name.

Now student doctor, what is the cause of Weber’s syndrome?

  • Weber’s syndrome is caused most likely by the occlusion of the posterior cerebral artery in the midbrain.

Now Weber’s syndrome can also result from what other possible cause?

  • From aneurysms of the circle of Willis.

Now let’s review that. Student doctor, what are the four main features of Weber’s syndrome?

  • And please pause. Hemiplegia, weakness of the lower face. Weakness of the lower tongue and palate, and hemiparesis of the trunk and extremities.

Student doctor, what is the cranial nerve affected in the midbrain that results in hemiplegia?

  • This is the oculomotor nerve, cranial nerve III.

Now, is the hemiplegia ipsilateral or contralateral?

  • The hemiplegia in Weber’s syndrome is contralateral.

Student doctor, what is the cranial nerve affected in Weber’s syndrome which results in weakness of the lower face?

  • This is the facial nerve, cranial nerve VII.

Is the weakness of the lower face ipsilateral or contralateral in Weber’s syndrome?

  • The weakness of the lower face is contralateral.

Student doctor, what is the cranial nerve affected which results in weakness of the tongue?

  • This is the hypoglossal nerve, cranial nerve XII.

Is the weakness of the tongue ipsilateral or contralateral?

  • In Weber’s syndrome, the weakness of the tongue is contralateral.

Now what is the cranial nerve affected in Weber’s syndrome which results in the weakness of the palate?

  • This is the vagus nerve, cranial nerve X.

Student doctor, what is the name of the syndrome characterized by the following features: eye abduction and depression, ptosis, intention tremor, loss of proprioception, tactile sensation, and vibration sensation from the trunk and the extremities?

  • This is the Benedict’s syndrome.

Student doctor, what is the cause of Benedict’s syndrome?

  • Occlusion or hemorrhage of the paramedian brances of the posterior cerebral artery.

Let’s review the signs of Benedict’s syndrome. What are the four main signs or categories of signs and symptoms?

  • First, eye abduction and depression.
  •  Second, ptosis.
  • Third, intention tremor.
  • Fourth, loss from the trunk and extremities, of proprioception and tactile sensation and vibration sensation.

****END OF TRANSCRIPTION****

Want More USMLE Step 1 Review Facts?

boardprep.net

Leave a Reply