Computer modeling of siphoning for CSF shunt design evaluation

A computer model of the cerebrospinal fluid (CSF) compartment and various shunt designs was developed to simulate CSF dynamics, particularly in the upright position in which siphoning is known to occur. This novel mathematical model of the CSF compartment incorporates negative pressure and volume components that permit simulation of siphoning. The model was tested with data from a previously reported animal experiment. The correspondence between the model simulation and the reported intracranial pressure and CSF shunt flow rate was very good. A simulation of a shunted hydrocephalic patient in the recumbent and upright position was then carried out to examine the effects of a standard shunt valve, an externally adjustable valve, a variable resistance valve, and an antisiphon device. The resulting pressure profiles, which conformed to previously reported data, indicate that this model would be useful for the evaluation of current and future shunt designs.