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Old 07-16-2016
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Default Explanation to this neuro q please

A 60 year old man is brought to the ER because of a severe headache and weakness on the left 3 hours after falling from a from a ladder and hitting his head on the sidewalk.He briefly lost consciousness but is awake on arrival at the ER .He is alert and oriented .His temperature is 36.1 C (97 F), pulse is 65/min, respirations are 12/min, and blood pressure is 160/100 mm hg. Neuro examination shows a dilated pupil on the RIGHT side and a normal left pupil..He has mild weakness of his LEFT upper and lower extremities.Which of the folowing is most likely on a CT scan of the head??

A) Brain stem haemorrhage
B) Herniation of cerebellar tonsils
C) Herniation of cingulate gyrus
D) Herniation of uncus
E) Subararachnoid hemorrhage.
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The stem of the question doesn't tell us which side of his head hit the sidewalk, but I'm presuming the it was the right side. In which case I suppose the CT scan would show an epidural hematoma and an uncal herniation.

D) Herniation of uncus

With an uncal herniation, there is ipsilateral eye dilation and contralateral limb paralysis. However, there may also be ipsilateral paralysis due to compression of the brain on the opposite side of the injury.

Here is a link to a powerpoint presentation... https://www.peacehealth.org/sites/de...esentation.pdf

The info below is from wikipedia...

Ipsilateral eye dilation

"The uncus can squeeze the oculomotor nerve (a.k.a. CN III), which may affect the parasympathetic input to the eye on the side of the affected nerve, causing the pupil of the affected eye to dilate and fail to constrict in response to light as it should."

Ipsilateral limb paralysis as a false localizing sign

"Another important finding is a false localizing sign, the so-called Kernohan's notch, which results from compression of the contralateral cerebral crus containing descending corticospinal and some corticobulbar tract fibers. This leads to Ipsilateral hemiparesis in reference to the herniation and contralateral hemiparesis with reference to the cerebral crus .Since the corticospinal tract predominately innervates flexor muscles, extension of the leg may also be seen."
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Thanks for the reply.But uncal herniation would present with oculomotor palsy , down and out.


In addition to it , it is the ipsilateral palsy which is more common in uncal herniation, the false localizing sign. Given in first aid.C/L palsy is not specified.

In favour of SAH ,

Severe headache , high systolic and diastolic pressure.

Also paresis can be there.

Can you rule SAH out here?
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"Pupillary dilation often precedes the somatic motor effects of CN III compression called oculomotor nerve palsy or third nerve palsy. "


The reason being that the parasympathetic nerves are compressed first.
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Ok but what about the contralateral paralysis ???
and points go against SAH??
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uncal herniation

i mentioned that the paralysis could be ipsilateral just for the sake of completeness. however, the paralysis is more commonly contralateral.

quote from the presentation above...

"Contralateral hemiparesis occurs with compression of the ipsilateral cerebral peduncle of the midbrain. Since the corticospinal tracts decussate below the midbrain, the hemiparesis is contrateral"


as for arguments against subararachnoid hemorrhage...
1. an epidural hematoma is more common following the type of trauma described
2. a subararachnoid hemorrhage presents with a sudden onset of a headache, possibility due to a ruptured aneurysm in the brain
3. a subararachnoid hemorrhage is not intrinsically tied to the neurologic deficits described
4. increased blood pressure, due to the cushing reflex, can occur with any cause of increased intracranial pressure
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Thanks for the wonderful explaination.
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no problem... i hope it helped
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