engleski

The investigation of cerebrospinal fluid formation by ventriculo-aqueductal perfusion method in cats

Objectives: The perfusion the cerebrospinal fluid (CSF) spaces by the arteficail CSF (aCSF) containing a of large molecular weight indicator, is an indirect method usually used to calculate net CSF formation. To evaluate this method we have developed a ventriculo-aqueductal perfusion method which enable a direct measurement of CSF formation in ventricles assuming that, at the physiological CSF pressure, the inflow rate should be smaller than outflow rate for net CSF formation. Methods: In chloralose anaesthetized cats the aqueduct of Sylvius was approached via transcerebellar route and cannulated so that outflow of the plastic cannula was positioned extracranially, and thereafter the skull was hermetically closed. Both lateral ventricles were also cannulated: one cannula was used for infusion of aCSF containing blue dextrane and the other one for measurement of CSF pressure. Results: During ventriculo-aqueductal perfusion (direct method) at the rate of 26.06 µ L/min at the physiological CSF pressure, the outflow rate from aqueductal cannula did not differ significantly from the inflow rate i.e. no CSF formation was observed. On the other hand, when indirect method based on dilution of blue dextran in outflowing perfusate was used to calculate the CSF formation, a net formation of nearly 5 µ ; ; ; ; ; ; L/min was obtained. Conclusion: Results attained by a direct method indicate that CSF formation inside brain ventricles does not exist, as we have suggested recently. The opposite results obtained by indirect method which is based on dilution of indicator substance in outflowing perfusate questioned this method a as reliable for study of CSF formation.

cerebrospinal fluid ; ventriculi-aqueductal perfusion ; CSF formation ; CSF pressure

Supplementum : Intracranial pressure and brain monitoring XII.