The Barrier Between the Blood and Cerebrospinal Fluid

Abstract

In a previous communication 1 the results of investigation of this barrier by means of the Walter bromide method were reported. It was found then that the series of mental diseases investigated could be divided into 3 classes according to the distribution ratio of bromides in the blood and cerebrospinal fluid. (1) In some of these diseases the distribution ratio was about normal (about 3 times as much bromide in the blood as there was in the cerebrospinal fluid and varying from 2.8 to 3.2). (2) In others this distribution ratio was higher. That is, less of the bromides passed into the cerebrospinal fluid. (3) In a third group the ratio was lower; that is, more bromides passed into the cerebrospinal fluid. Most of the diseases belonging to the third group were of the type where one finds affections of the smaller cerebral vessels.

In discussing the nature of this phenomenon the question was brought up as to whether this distribution of bromides could be regarded as due to a process of dialysis. The fact that there was 3 times as much of the bromides in the blood as there was in the cerebrospinal fluid apparently argued against it, for in the case of chlorides, for instance, we find a distribution of 1.0 in the blood to about 1.2 in the cerebrospinal fluid. It was suggested then that some of the bromides may be fixed in some way in the blood and rendered indiffusible. This would mean that the nature of the membrane itself, (whatever it may be) that separates the blood from the cerebrospinal fluid was not the governing factor.

Since then we have been investigating this question and some results obtained apparently argued this possibility.