Properties of the Lymphatic Cerebrospinal Fluid Transport System in the Rat: Impact of Elevated Intracranial Pressure

Abstract

Previous studies suggested that a major portion of cerebrospinal fluid (CSF) is absorbed by extracranial lymphatics located in the olfactory turbinates. The objective of this study was to determine the impact of elevated intracranial pressure (ICP) on downstream cervical lymphatic pressures in the rat. Pressures were measured in the deep cervical lymph nodes using a servo-null micropressure system. A catheter was placed in a lateral ventricle and fluid was infused from a reservoir at defined ICPs. When Ringer’s solution was infused, elevations of ICP from 10 to 50 cm H₂O resulted on average in a reduction of diastolic cervical node pressures. In contrast, when a diluted plasma solution (80% plasma in Ringer’s) was infused, downstream diastolic lymphatic pressures increased as ICP was elevated to 50 cm H₂O. These data are consistent with the view that much of the CSF-derived water that convects into the lymphatics is absorbed into the ethmoidal or nodal blood vessels. This study supports the concept of fluid continuity between the subarachnoid space and extracranial lymphatics and suggests that this loss of CSF-derived water may act as a safety mechanism to reduce the volume load to the downstream lymphatic vessels.

Idiopathic intracranial hypertension (Pseudotumor cerebri)

“…Decreased conductance to CSF outflow may be due to dysfunction of the absorptive mechanism of arachnoid granulations or extracranial lymphatics [8]. This latter mechanism of an alternative route of drainage through extracranial lymphatics, proposed by Koh et al [9], may be an important factor in the mechanism of IIH because this route may account for a substantial percentage of CSF absorption.…”

Intranasal administration of oxytocin: Behavioral and clinical effects, a review

“…The vast majority of studies concerning the morphological details of 'nose-brain-relationships' aimed at the olfactory and other routes for cerebrospinal fluid drainage and were 'looking for' possible mechanisms working in the 'opposite direction' (Bradbury and Westrop, 1983;Erlich et al, 1986;Gomez et al, 1985;Johnston et al, 2004Johnston et al, , 2005Johnston et al, , 2007aJohnston, 2003;Kida et al, 1993Kida et al, , 1995Koh et al, 2007Koh et al, , 2005Koh et al, , 2006Li et al, 2005b;Nagra et al, 2006Nagra et al, , 2008Papaiconomou et al, 2004;Pollock et al, 1997;Walter et al, 2006a,b;Weller et al, 1992Weller et al, , 2008Zakharov et al, 2003Zakharov et al, , 2004. Walter et al (2006b) described in detail a putative model of labyrinthine channels, surrounding the olfactory fibers during their passage of the cribriform plate providing the CSF with a route for draining into the lymphatic system with the possible side-effect of stimulating antibody-production in the cervical lymph nodes (Walter et al, 2006a).…”

The translaminar pressure gradient in sustained zero gravity, idiopathic intracranial hypertension, and glaucoma

“…Some CSF drainage occurs via arachnoidal granulations into the cerebral venous system, so an elevation in venous pressure leads to a rise in CSFp also [38]. Additional CSF drainage occurs into olfactory and optic nerve meningeal lymphatics in animals and humans [39][40][41][42]. The meningeal lymphatics are particularly dense around the termination of the ONSAS [42].…”