Experimental determination of the Stern layer thickness at the interface of the human arachnoid membrane and the cerebrospinal fluid.

The paper is part of an investigation of the electrostatic forces contributing to the interaction between colloidal molecules, suspended in the cerebrospinal fluid, with other molecules of the cerebrospinal fluid and with the surrounding environment. The study is based on experimental observations and theoretical considerations. We are reporting about the microscopic observation of particles suspended in the cerebrospinal fluid which was obtained by lumbar puncture of 27 neurosurgery patients. We found that the mean particle diameter and therefore the mean thickness of the Stern layer at the interface of the arachnoid membrane with the cerebrospinal fluid is a few micrometers. Individual variations of this diameter have been observed.