Intracranial pressure elevation alters CSF clearance pathways.
Fluids Barriers CNS
; 17(1): 29, 2020 Apr 16.
Article
in En
| MEDLINE
| ID: mdl-32299464
ABSTRACT
BACKGROUND:
Infusion testing is a common procedure to determine whether shunting will be beneficial in patients with normal pressure hydrocephalus. The method has a well-developed theoretical foundation and corresponding mathematical models that describe the CSF circulation from the choroid plexus to the arachnoid granulations. Here, we investigate to what extent the proposed glymphatic or paravascular pathway (or similar pathways) modifies the results of the traditional mathematical models.METHODS:
We used a compartment model to estimate pressure in the subarachnoid space and the paravascular spaces. For the arachnoid granulations, the cribriform plate and the glymphatic circulation, resistances were calculated and used to estimate pressure and flow before and during an infusion test. Finally, different variations to the model were tested to evaluate the sensitivity of selected parameters.RESULTS:
At baseline intracranial pressure (ICP), we found a very small paravascular flow directed into the subarachnoid space, while 60% of the fluid left through the arachnoid granulations and 40% left through the cribriform plate. However, during the infusion, 80% of the fluid left through the arachnoid granulations, 20% through the cribriform plate and flow in the PVS was stagnant. Resistance through the glymphatic system was computed to be 2.73 mmHg/(mL/min), considerably lower than other fluid pathways, giving non-realistic ICP during infusion if combined with a lymphatic drainage route.CONCLUSIONS:
The relative distribution of CSF flow to different clearance pathways depends on ICP, with the arachnoid granulations as the main contributor to outflow. As such, ICP increase is an important factor that should be addressed when determining the pathways of injected substances in the subarachnoid space. Our results suggest that the glymphatic resistance is too high to allow for pressure driven flow by arterial pulsations and at the same time too small to allow for a direct drainage route from PVS to cervical lymphatics.Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Subarachnoid Space
/
Intracranial Pressure
/
Cerebrospinal Fluid
/
Intracranial Hypertension
/
Glymphatic System
/
Models, Biological
Type of study:
Prognostic_studies
Limits:
Humans
Language:
En
Journal:
Fluids Barriers CNS
Year:
2020
Document type:
Article
Affiliation country: