Assessment of cerebrospinal fluid outflow resistance.
The brain and the spinal cord are contained in a cavity and are surrounded by cerebrospinal fluid (CSF), which provides physical support for the brain and a cushion against external pressure. Hydrocephalus is a disease, associated with disturbances in the CSF dynamics, which can be surgically treated by inserting a shunt or third ventriculostomy. This review describes the physiological background, modeling and mathematics, and the investigational methods for determining the CSF dynamic properties, with specific focus on the CSF outflow resistance, R out. A model of the cerebrospinal fluid dynamic system, with a pressure-independent R out, a pressure-dependent compliance and a constant formation rate of CSF is widely accepted. Using mathematical expressions calculated from the model, along with active infusion of artificial CSF and observation of corresponding change in ICP allows measurements of CSF dynamics. Distinction between normal pressure hydrocephalus and differential diagnoses, prediction of clinical response to shunting and the possibility of assessment of shunt function in vivo are the three most important applications of infusion studies in clinical practice.
Eklund
Anders
A
Department of Biomedical Engineering and Informatics, Umeå University Hospital, 90185 Umeå, Sweden. anders.eklund@vll.se
Smielewski
Peter
P
Chambers
Iain
I
Alperin
Noam
N
Malm
Jan
J
Czosnyka
Marek
M
Marmarou
Anthony
A
D002555:Cerebrospinal Fluid / Q000502:physiology*; D015170:Cerebrospinal Fluid Pressure / Q000502:physiology*; D003187:Compliance; D003937:Diagnosis, Differential; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000175:diagnosis / Q000503:physiopathology; D008959:Models, Neurological