Triad for transtentorial/uncal herniation

[loveoforganic]

---

Members do not see this ad.

Just want to sure this up:

Increased ICP due to mass effect --> herniation ipsilateral to region of mass

- Compression of III ipsilateral to the mass -> lateral strabismus and mydriasis ipsilateral to the mass

- Compression of PCA ipsilateral to the mass -> Ischemia of the primary visual cortex ipsilateral to the mass -> Homonymous hemianopsia contralateral to the mass

- Compression of the crus cerebri contralateral to the mass (Kernohan's notch) -> Hemiparesis (more or less from the neck down) ipsilateral to the mass

Thanks

 

[Morsetlis]

Sounds like Weber's with hemianopsia, and I'd expect a huge headache.

 

[Aclamity]

Just want to sure this up:

Increased ICP due to mass effect --> herniation ipsilateral to region of mass

- Compression of III ipsilateral to the mass -> lateral strabismus and mydriasis ipsilateral to the mass

- Compression of PCA ipsilateral to the mass -> Ischemia of the primary visual cortex ipsilateral to the mass -> Homonymous hemianopsia contralateral to the mass

- Compression of the crus cerebri contralateral to the mass (Kernohan's notch) -> Hemiparesis (more or less from the neck down) ipsilateral to the mass

Thanks

Bringing this up again because NBME 7 had a question where the fellow with uncal herniation had contralateral paresis... anyone else catch that? Does this mean uncal herniations can cause both?

 

[AndyRSC]

Was it in the context of an epidural hematoma? I've seen this alternate. All my step 2 sources are divided right down the middle on whether paresis is ipsilateral or contralateral in that scenario. The ipsilateral occurs by the mechanism outlined above. The contralateral occurs, I would guess, by direct compression of the motor cortex by the hematoma.

 

[usmleq]

I learned that initially you get contralateral hemiparesis and can develop ipsi hemiparesis if it is severs enough b/c of kernohans notch

 

[Aclamity]

I learned that initially you get contralateral hemiparesis and can develop ipsi hemiparesis if it is severs enough b/c of kernohans notch

Yeah, I mean feasibly it could cause both, depending on how far the uncus herniated. I just figured that if there was a "classic triad" it meant that the ipsilateral paresis was overwhelmingly more common than contralateral (in which case Step 1 would likely present it that way hah)