Alterations of intracranial tension by salt solutions in the alimentary canal

Abstract

In two interesting and suggestive papers 1 Weed and McKibben demonstrated the significant physiological fact that it is possible to reduce the cerebrospinal fluid pressure and diminish the bulk of the brain by injecting a hypertonic solution into the blood stream. Conversely they found that hypotonic solutions had the opposite effect: a rise of cerebrospinal fluid pressure and an increase of brain bulk. In the course of our studies their work has been repeated and their general conclusions confirmed.

The clinical bearing of these facts is obvious. Particularly they concern the states commonly referred to as “pressure symptoms.” By similar methods it has been found possible to secure these same results in patients with increased degrees of intracranial tension. It was felt that the undesirable effects on pulse, respiration and blood pressure of such intravenous injections might contraindicate their use. For this reason the effects of gastrointestinal doses of hypertonic solutions were studied.

In a large series of animal experiments it has been found that practically the same effects may be obtained by the gastrointestinal route of administration. By this method the intracranial changes are not attended by disturbances of pulse, respiration or blood pressure, also the possible alterations of the cellular elements of the blood are avoided.

Twenty to thirty cubic centimeters of a saturated sodium chloride solution introduced into the duodenum or rectum of an average-sized cat produced a maximal fall of cerebrospinal fluid pressure precisely comparable to that which occurred when the solution was given intravenously. Following such doses the average fall of pressure in a large series of experiments was 258 mm. normal saline. The changes were roughly proportionate to the concentration of the salt and the size of the dose.