Dependence of Cerebrospinal Fluid Pressure and Volume on the Changes in Serum Osmolarity in Cats

Abstract

We conclude that changes in serum osmolarity change the CSF volume because of the osmotic gradient between the blood and all of the CSF compartments, and also that the change in CSF pressure is closely associated with changes in CSF volume.

“Compensated hyperosmolarity” of cerebrospinal fluid and the development of hydrocephalus

“…water) in the CSF system. It has recently been proposed that development of hydrocephalus (Krishnamurthy et al, 2009;Orešković and Klarica, 2011) and the change in CSF volume is caused by changes in blood or CSF osmolarity (Hochwald et al, 1974;Wald et al, 1976;Orešković et al, 2002;Maraković et al, 2010;Jurjević et al, 2012) and that elevated CSF osmolarity should be considered as one of the most important factors in excessive CSF/water accumulation. We have also presumed that the greatest responsibility for the maintenance of CSF iso-osmolarity is the rapid extraction of water from the bloodstream into the osmotically loaded CSF space, and that extracted water would consequently cause an accumulation of fluid, increase in ICP and the development of hydrocephalus.…”

“…As there are almost no obstacles/barriers for water within the CNS, and as water quickly and easily crosses from one compartment to another (blood, CSF, ISF, intracellular fluid), the cause of excessive fluid accumulation should be searched for in pathophysiological conditions leading to the displacement of water into the CSF space, and its accumulation within the CSF system. It is well documented that osmotic gradients play a significant part in the regulation of brain water and CSF volume (Hochwald et al, 1974;Wald et al, 1976;Orešković et al, 2002;Maraković et al, 2010;Jurjević et al, 2012). Because of this, it has been presumed that without significant obstruction or stenosis of the CSF system, all pathological processes in which an increase of CSF osmolarity (the osmotic load of CSF) takes place should lead to an increase in CSF volume, and consequently should cause hydrocephalus (Krishnamurthy et al, 2009;Orešković and Klarica 2010; what speaks in favor the most recent multiinstitutional studies of hydrocephalus as a consequence of hemispherectomy surgery for medically intractable epilepsy treatment (Lew et al, 2013).…”

New Concepts of Cerebrospinal Fluid Physiology and Development of Hydrocephalus

“…Entrance of water from the blood into the osmolar loading part of the CSF system was experimentally well documented [35,37,55] . There is no doubt that the CSF volume is regulated by changes in osmolarity, i.e., an increase in osmolarity outside the CSF system would reduce the CSF volume, whereas increased CSF osmolarity would increase the CSF volume [37,[63][64][65] . Most importantly, in all of the mentioned experiments, the CSF system had been fully passable during the process of hydrocephalus development.…”

Monoamine Neurotransmitter Metabolite Concentration as a Marker of Cerebrospinal Fluid Volume Changes

“…We previously showed [ 12 ] that osmotic forces signifi cantly infl uence the control of CSF volume and that the decrease in blood osmolarity resulted in an increase in CSF volume (Fig. 2 ) [ 9 ], most probably (mainly) by water infl ow into the CSF compartments [ 10 ]. As these changes (decrease) in HVA concentration occurred at the same time as the changes (increase) in CSF volume induced by the i.p.…”

“…We also demonstrated that, in accordance with our new proposed hypothesis, alterations in serum and CSF osmolarity change the CSF volume owing to the osmotic gradient between the blood and all of the CSF compartments, and the change in CSF pressure is closely associated with changes in CSF volume [ 9 , 10 ]. In our model of free cisternal drainage in the anesthetized cats [ 9 ], a signifi cant increase in the outfl ow rate after the intraperitoneal (i.p.) administration of a hypoosmolar substance (distilled water) was demonstrated.…”