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  #1  
Old 02-18-2012
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Question Normal pressure versus communicating hydrocephalus

can any one explain to me the difference between normal pressure and communicating hydrocephalus as both due to decrease absorption of csf in arachnoid villi
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Old 02-18-2012
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Normal pressure is associated with decreasing cerebral mass (Atrophy) as in aging the communicating one is not.
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also presentations are different.
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Quote:
Originally Posted by Drbooda View Post
Normal pressure is associated with decreasing cerebral mass (Atrophy) as in aging the communicating one is not.

no thats hydrocephalus in ex vaco
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Quote:
Originally Posted by haga View Post
also presentations are different.
how they different in presentation???
and hydrdcephalus question in general dont depend on s/s
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Quote:
Originally Posted by rose View Post
how they different in presentation???
and hydrdcephalus question in general dont depend on s/s
Differentiate hydrocephalus into 2 categories....normal pressure and increased pressure.

Normal Pressure:

1. Normal pressure hydrocephalus is what the name suggests. The pressure in this case is NORMAL and it occurs in the elderly. Classic triad of Dementia, Ataxia and Urinary Incontinence. You don't see the typical signs of herniation, papilledema or increased pressure. The CSF is not absorbed by the arachnoid villi and ventricles enlarge and press the cortex against the skull.

2. Hydrocephalus ex vacuo where there is increased CSF due to cerebral atrophy. In this case the intracranial pressure is also normal. This is not a pathology of CSF rather the ventricles just look dilated compared to the atrophied brain so you don't get any hydrocephalus s/s.

The way to differentiate these 2 is the triad of dementia, ataxia and urinary incontinence. Does NOT happen in hydrocephalus ex vacuo.



Increased Pressure:

Both of these have increased intracranial pressure and typical signs of hydrocephalus such as papilledema and herniation which are not seen in the normal pressure varieties.

1. Communicating is due to decreased CSF absorption or increased CSF production. Most common cause is destruction of the arachnoid villi (perform absorption) due to post meningitis scarring.

Non-Communicating: Obstruction somewhere in the pathway, most commonly the aqueduct. Other common locations are 1 or more foramen of monro and 1 or more openings that exit from 4th ventricle. Basically remember that most commonly the obstruction is NOT in the ventricles but in the passages that conduct the CSF.
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thanks alot , it seems I did know nothing about it
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Old 11-04-2012
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Quote:
Originally Posted by haga View Post
Differentiate hydrocephalus into 2 categories....normal pressure and increased pressure.

Normal Pressure:

1. Normal pressure hydrocephalus is what the name suggests. The pressure in this case is NORMAL and it occurs in the elderly. Classic triad of Dementia, Ataxia and Urinary Incontinence. You don't see the typical signs of herniation, papilledema or increased pressure. The CSF is not absorbed by the arachnoid villi and ventricles enlarge and press the cortex against the skull.

2. Hydrocephalus ex vacuo where there is increased CSF due to cerebral atrophy. In this case the intracranial pressure is also normal. This is not a pathology of CSF rather the ventricles just look dilated compared to the atrophied brain so you don't get any hydrocephalus s/s.

The way to differentiate these 2 is the triad of dementia, ataxia and urinary incontinence. Does NOT happen in hydrocephalus ex vacuo.



Increased Pressure:

Both of these have increased intracranial pressure and typical signs of hydrocephalus such as papilledema and herniation which are not seen in the normal pressure varieties.

1. Communicating is due to decreased CSF absorption or increased CSF production. Most common cause is destruction of the arachnoid villi (perform absorption) due to post meningitis scarring.

Non-Communicating: Obstruction somewhere in the pathway, most commonly the aqueduct. Other common locations are 1 or more foramen of monro and 1 or more openings that exit from 4th ventricle. Basically remember that most commonly the obstruction is NOT in the ventricles but in the passages that conduct the CSF.
But if in both the communicating hydrocephalus and the normal pressure hydrocephalus the CSF is not being reabsorbed why is the clinical/pressure outcome different?
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Old 11-04-2012
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Quote:
Originally Posted by OVRPS View Post
But if in both the communicating hydrocephalus and the normal pressure hydrocephalus the CSF is not being reabsorbed why is the clinical/pressure outcome different?

I think the causes are not same......................though normal pressure hydrocephalus is a type of communicating hydrocephalus............most causes for NPH are unknown too............difficult to comment.
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Normal Pressure Hydrocephalus
It is seen in the elderly, as enlargement of the ventricles due to the normal aging process of their (soon us) brains getting smaller
The subarachnoid space does not change.

Communicating Hydrocephalus
The arachnoid villi that normally drains the CSF via absorption are damaged. Insults can be post-meningitis infections. The lack of absorption causes increase pressure. CSF circulation is not blocked hence Communicating.

VS

Non-Communicating Hydropcephalus - CSF drainage thats being blocked
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Quote:
Originally Posted by Ergo Proxy View Post
Normal Pressure Hydrocephalus
It is seen in the elderly, as enlargement of the ventricles due to the normal aging process of their (soon us) brains getting smaller
The subarachnoid space does not change.

Communicating Hydrocephalus
The arachnoid villi that normally drains the CSF via absorption are damaged. Insults can be post-meningitis infections. The lack of absorption causes increase pressure. CSF circulation is not blocked hence Communicating.

VS

Non-Communicating Hydropcephalus - CSF drainage thats being blocked

But then ex-vacuo comes in because it says is is seen in atrophy, something similar as in the elderly i think
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Quote:
Originally Posted by OVRPS View Post
But then ex-vacuo comes in because it says is is seen in atrophy, something similar as in the elderly i think
A question stem would not point you to Ex-Vacuo unless they present with Alzheimer, Pick's Disease, or Advanced HIV. - Ex-Vacuo does not have the triad that we see in Normal Pressure Hydrocephalus, which is Wet Wobbly Wacky
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Quote:
Originally Posted by Ergo Proxy View Post
A question stem would not point you to Ex-Vacuo unless they present with Alzheimer, Pick's Disease, or Advanced HIV. - Ex-Vacuo does not have the triad that we see in Normal Pressure Hydrocephalus, which is Wet Wobbly Wacky
But the mechanism of disease is the same then? Atrophy? But one is due to aging and the other one due to disease?
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Old 03-04-2013
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Default causes of Normal pressure

This is for whoever is still searching for an answer:
Normal Pressure Hydrocephalus is the same concept as ex vacuo Hydrocephalus but the cause is not atrophy. I suspect people haven't come to an agreement on it yet but altered compliance of ventricular walls and/or increased viscosity of CSF can be at fault.
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Old 06-08-2013
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Default Normal Pressure vs Increased Pressure, Communicating Hydrocephalus

I also ran into the same question. I believe that the major difference between normal pressure and increased pressure, communicating hydrocephalus is the response of the choroid plexus to decreased CSF absorption into the venous sinuses by the arachnoid granulations.

In normal pressure hydrocephalus, the choroid responds appropriately to increasing pressure and stops production of CSF. The name "normal pressure hydrocephalus" is a misnomer because pressure is increased compared to normal. The pathogenesis of this disease is based on increased pressure causing stretching of the corona radiata, represented in the triad of wet, whacky, and wobbly. Also the symptoms are relieved lumbar puncture, further supporting that the pressure is actually slightly increased. A more appropriate name might be "normal volume hydrocephalus", because the response by the choroid plexus to decrease CSF production does not exert enough pressure on the ventricles to cause radiological evidence of expansion. More clinically important, the choroid plexus response does not cause an increased risk of herniation in normal pressure hydrocephalus, distinguishing it from increase pressure, communicating hydrocephalus.
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Quote:
Originally Posted by rose View Post
can any one explain to me the difference between normal pressure and communicating hydrocephalus as both due to decrease absorption of csf in arachnoid villi
normal pressure is commonly idiopathic as communicating is due to inflammation
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