karusmle
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a 37 yr old is in a serious automobile accident and sustained a close head injury,she does not immediately seek medical attention,but is brought to the emergency room two hours later by her brother,on physical examination there is mydriasis and loss of pupillary light reflex,several hours later she is unable to follow a flash light with her eyes,which of the following herniation is most likely occuring in this patient????
A)cerebellar tonsils into the forman magnum
B)cerebellum upward past the tentorium
C)singulate gyrus under the falx
D)medulla into the foramen magnum
E)temporal lobe under the tentorium
ans with explanation
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| cyra
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I think it is E)temporal lobe herniation under the tentorium.This would constitute a descending transtentorial herniation.
Mydriasis and loss of the pupillary light reflex....There is paresis of the 3rd cranial nerve due to compression of the parasympathetic fibres located at the outer 3rd aspect of the nerve ....this dysfunction of the PS fibers and unopposed action of the Symp. fibers leads to mydriasis.
The inability to follow a flash light after a few hours would be attributable to further damage to the nerve resulting in denervation of the extraocular muscles(causing the eyes to look down and out due to unoppsed action of lat. rectus and sup.oblique)
A and D...are examples of foramen magnum herniation.Clincal features of such a herniation are bilat. arm dysthesias and obtundation.An acute foramne magnum herniation may be clinically catastrophic as the brain herniated through the foramen magnum.
B...is an ascending tentorial herniation ususally caused by a slow growing cerebellar or brainstem process..e.g...a diffusely infiltrating astrocytoma.clincal features are nausea and vomiting followed by obtundation.Progression to obtundation can be very rapid and therefore ca be considered an emergency depending on the length of time the mass has been in the post. fossa.
C...is a subfalcine hernaition.It can occur in siolation or with transtentorial herniation.Has no severe clinical symptomatology.Clinical features include headache and later on as the herniation progresses,contarlat. leg weakness.
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| ssrpk
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i agree with cyra, excellent explanation.
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| p53
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Actually, to be more concrete, it's harniation of the hyppocampal uncus on the same side (where tumor or hamatoma is), with ipsilateral oculomotor nerve damage. Kernohan notch may be on the other side, but not in this case - there isn't contralateral hemiparesis.
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| karusmle
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thank u guys , especially to cyra for those good explanation,where did u do ur CNS???robins???i did goljan and nothing much is given ,can u advice me on the text for CNS???
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| cyra
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You are welcome karusmle...I found CNS difficult too!!...and i still do...i have gone through BRS pathology...its pretty ok!...see...what has helped me alot is browsing through these forums...if i see a question to which i don't know the answer...i look it up..text books...google it..wat ever!..for example, the question above...i knew it had to be E because of the clinical features...but had to look up the cardinal clinical features for the rest...so i should be thanking you for posting the question!....try making little notes or flash cards for every difficult question you come across for future reference..hope it helps!
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| karusmle
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thank u so much cyra for these tips......r u active in any other forums????can u mention them if u r ........
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| mildus
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there are 19 types of CNS tumors, is there any mnemonics or something to help us memorise all of them?
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