The Influence of Body Position on Cerebrospinal Fluid Pressure Gradient and Movement in Cats with Normal and Impaired Craniospinal Communication

Abstract

Intracranial hypertension is a severe therapeutic problem, as there is insufficient knowledge about the physiology of cerebrospinal fluid (CSF) pressure. In this paper a new CSF pressure regulation hypothesis is proposed. According to this hypothesis, the CSF pressure depends on the laws of fluid mechanics and on the anatomical characteristics inside the cranial and spinal space, and not, as is today generally believed, on CSF secretion, circulation and absorption. The volume and pressure changes in the newly developed CSF model, which by its anatomical dimensions and basic biophysical features imitates the craniospinal system in cats, are compared to those obtained on cats with and without the blockade of craniospinal communication in different body positions. During verticalization, a long-lasting occurrence of negative CSF pressure inside the cranium in animals with normal cranio-spinal communication was observed. CSF pressure gradients change depending on the body position, but those gradients do not enable unidirectional CSF circulation from the hypothetical site of secretion to the site of absorption in any of them. Thus, our results indicate the existence of new physiological/pathophysiological correlations between intracranial fluids, which opens up the possibility of new therapeutic approaches to intracranial hypertension.

A new look at cerebrospinal fluid movement

“…In both cases, our findings could not be fitted into “classic” CSF physiology hypothesis. Furthermore, our recent experiments in anaesthetized cats involved no surgical intervention apart from invasive CSF pressure monitoring [11]. We observed the hydrostatic pressure gradient in the upright position and found a long-lasting sub-atmospheric intracranial pressure, zero CSF pressure in the cervical region and +30 cm H 2 O in the lumbar region.…”

“…We observed the hydrostatic pressure gradient in the upright position and found a long-lasting sub-atmospheric intracranial pressure, zero CSF pressure in the cervical region and +30 cm H 2 O in the lumbar region. This does not support the traditional CSF “circulation” along the cranio-spinal CSF space because CSF can only flow from a region of higher to a region of lower CSF pressure [11]. …”

“…It is true that our research has not been conducted at the molecular or cellular level, but that is because we were investigating this phenomenon at the level of systems physiology [3-11]. However, our hypothesis has been strongly supported and our investigation extended as in a recent molecular study of Nakada’s research team [15], who analyzed water passage from the brain into the CSF in aquaporin-1 (AQP-1), aquaporin-4 knockout and wild-type mice using a newly-developed water molecular MRI technique.…”

“…However, CSF/water volume is slowly carried bidirectionally along all CSF spaces by the systolic-diastolic to-and-fro displacement [3,10]. This movement of fluid is different in the spinal, compared to the cranial subdural space, due to different anatomical and biophysical characteristics of the cranial and spinal compartments [10,11,21-24]. Namely in the cranium, the dura is firmly attached to the bone and the subdural volume cannot not be changed significantly.…”

New Concepts of Cerebrospinal Fluid Physiology and Development of Hydrocephalus

“…3 ) [39,40,49] . Together with pulsatile movement as a consequence of large vessel pulsations, there are additional CSF movements which occur inside the spinal SAS due to cervicolumbar CSF volume redistribution, which is a result of gravity influence in different body positions [39,40,49] .…”