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Measurement of cerebrospinal fluid formation and absorption by ventriculo-cisternal perfusion: what is really measured?

Orešković D, Klarica M - Croat. Med. J. (2014)

Bottom Line: The generally accepted hypothesis on cerebrospinal fluid (CSF) hydrodynamics suggests that CSF is actively formed mainly by the choroid plexuses, circulates unidirectionally along the brain ventricles and subarachnoid space, and is passively absorbed mainly into the dural venous sinuses.CSF formation rate (Vf) has been extensively studied using the ventriculo-cisternal perfusion technique and the results have been used as the key evidence confirming the mentioned hypothesis.This technique allows "calculation" of the CSF formation even in dead animals, in an in vitro model, and in any other part of the CSF system outside the ventricles that is being perfused.

View Article: PubMed Central - PubMed

Affiliation: Darko Orešković, Rudjer Bošković Institute, Department of Molecular Biology, Bijenička 54, 10 000 Zagreb, Croatia, doresk@irb.hr.

ABSTRACT
The generally accepted hypothesis on cerebrospinal fluid (CSF) hydrodynamics suggests that CSF is actively formed mainly by the choroid plexuses, circulates unidirectionally along the brain ventricles and subarachnoid space, and is passively absorbed mainly into the dural venous sinuses. CSF formation rate (Vf) has been extensively studied using the ventriculo-cisternal perfusion technique and the results have been used as the key evidence confirming the mentioned hypothesis. This technique and the equation for Vf calculation are based on the assumption that the dilution of the indicator substance is a consequence of the newly formed CSF, ie, that a higher CSF formation rate will result in a higher degree of dilution. However, it has been experimentally shown that the indicator substance dilution inside the CSF system does not occur because of a "newly formed" CSF, but as consequence of a number of other factors (departure of substances into the surrounding tissue, flowing around the collecting cannula into the cortical and spinal subarachnoid space, departure into the contralateral ventricle, etc). This technique allows "calculation" of the CSF formation even in dead animals, in an in vitro model, and in any other part of the CSF system outside the ventricles that is being perfused. Therefore, this method is indirect and any dilution of the indicator substance in the perfusate caused by other reasons would result in questionable and often contradictory conclusions regarding CSF formation rates.

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Different types of cerebrospinal fluid system perfusion methods in cats (A and B) and dogs (C and D).
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Figure 3: Different types of cerebrospinal fluid system perfusion methods in cats (A and B) and dogs (C and D).

Mentions: Furthermore, since the method is indirect and depends on marker dilution by “newly formed CSF” and since a marker can pass from the CSF into the brain parenchyma (5,23-26), Vf should be calculated in any part of the CSF system that will be perfused. Except the most frequent type of ventriculo-cisternal perfusion method, other types of perfusion have been performed in the CSF system of cats and dogs – lateroventricular-lateroventricular, ventriculo-aqueductal, cortico-cisternal, corticofrontal-corticofrontal, cervical-lumbosacral, and lumbosacral-cervical (Figure 3) (15,16,22,38-40), and in each of these models a significant amount of net CSF formation has been calculated. So, we can actually show that CSF is formed inside the ventricles (if we perfuse the ventricles; Figure 3 A and B), but also inside the cortical and spinal subarachnoid space (if we perfuse these parts of the CSF system; Figure 3 C and D). Thus, we can show CSF formation using the equation of Heisey et al (21) anywhere (in whichever segment someone decides to perfuse) because, due to various factors, marker dilution will occur in any case.


Measurement of cerebrospinal fluid formation and absorption by ventriculo-cisternal perfusion: what is really measured?

Orešković D, Klarica M - Croat. Med. J. (2014)

Different types of cerebrospinal fluid system perfusion methods in cats (A and B) and dogs (C and D).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4157383&req=5

Figure 3: Different types of cerebrospinal fluid system perfusion methods in cats (A and B) and dogs (C and D).
Mentions: Furthermore, since the method is indirect and depends on marker dilution by “newly formed CSF” and since a marker can pass from the CSF into the brain parenchyma (5,23-26), Vf should be calculated in any part of the CSF system that will be perfused. Except the most frequent type of ventriculo-cisternal perfusion method, other types of perfusion have been performed in the CSF system of cats and dogs – lateroventricular-lateroventricular, ventriculo-aqueductal, cortico-cisternal, corticofrontal-corticofrontal, cervical-lumbosacral, and lumbosacral-cervical (Figure 3) (15,16,22,38-40), and in each of these models a significant amount of net CSF formation has been calculated. So, we can actually show that CSF is formed inside the ventricles (if we perfuse the ventricles; Figure 3 A and B), but also inside the cortical and spinal subarachnoid space (if we perfuse these parts of the CSF system; Figure 3 C and D). Thus, we can show CSF formation using the equation of Heisey et al (21) anywhere (in whichever segment someone decides to perfuse) because, due to various factors, marker dilution will occur in any case.

Bottom Line: The generally accepted hypothesis on cerebrospinal fluid (CSF) hydrodynamics suggests that CSF is actively formed mainly by the choroid plexuses, circulates unidirectionally along the brain ventricles and subarachnoid space, and is passively absorbed mainly into the dural venous sinuses.CSF formation rate (Vf) has been extensively studied using the ventriculo-cisternal perfusion technique and the results have been used as the key evidence confirming the mentioned hypothesis.This technique allows "calculation" of the CSF formation even in dead animals, in an in vitro model, and in any other part of the CSF system outside the ventricles that is being perfused.

View Article: PubMed Central - PubMed

Affiliation: Darko Orešković, Rudjer Bošković Institute, Department of Molecular Biology, Bijenička 54, 10 000 Zagreb, Croatia, doresk@irb.hr.

ABSTRACT
The generally accepted hypothesis on cerebrospinal fluid (CSF) hydrodynamics suggests that CSF is actively formed mainly by the choroid plexuses, circulates unidirectionally along the brain ventricles and subarachnoid space, and is passively absorbed mainly into the dural venous sinuses. CSF formation rate (Vf) has been extensively studied using the ventriculo-cisternal perfusion technique and the results have been used as the key evidence confirming the mentioned hypothesis. This technique and the equation for Vf calculation are based on the assumption that the dilution of the indicator substance is a consequence of the newly formed CSF, ie, that a higher CSF formation rate will result in a higher degree of dilution. However, it has been experimentally shown that the indicator substance dilution inside the CSF system does not occur because of a "newly formed" CSF, but as consequence of a number of other factors (departure of substances into the surrounding tissue, flowing around the collecting cannula into the cortical and spinal subarachnoid space, departure into the contralateral ventricle, etc). This technique allows "calculation" of the CSF formation even in dead animals, in an in vitro model, and in any other part of the CSF system outside the ventricles that is being perfused. Therefore, this method is indirect and any dilution of the indicator substance in the perfusate caused by other reasons would result in questionable and often contradictory conclusions regarding CSF formation rates.

Show MeSH