Effects of proteins, blood cells and glucose on the viscosity of cerebrospinal fluid

It has long been assumed that cerebrospinal fluid (CSF) is a newtonian fluid with viscosity similar to water, yet high protein content, has been postulated to increase the viscosity of CSF in vivo. Such an increase in viscosity may have serious implications for the effectiveness of surgical shunts implanted to re-establish the CSF flow in cases of abnormal CSF circulation. In this study, glucose content, total protein content and blood cell count in the CSF of 23 patients undergoing brain surgery were measured. Viscosity measurements were performed on duplicate CSF samples over a range of shear strain rates of 25-1,460 s-1. The results indicated that high protein or high cell concentration in CSF does not significantly affect the viscosity of the cerebral fluid at those shear rates. CSF is clearly newtonian, and its viscosity at 37 degreesC is in the range of 0.7-1 mPa.s.