A NOTE ON THE RELATIONSHIP OF CEREBROSPINAL AND INTRALABYRINTHINE PRESSURES

Abstract

A new method for the accurate determination of intralabyrin thine pressure is based on the Wever and Bray phe nomenon. The relationship between this pressure and cerebrospinal fluid pressure was studied and the effect of changes in the latter determined. Using intravenous injections of hypertonic salt or distilled water sharp changes in cerebrospinal fluid pressure could be produced and the effect upon intralabyrinthine pressure studied. These pressures varied always in the same direction al though the extremes of intralabyrinthine pressure were reached sometime after the extremes in cerebrospinal fluid pressure. It was also noted for the first time that an increased intralabyrinthine pressure did not affect the ability of the cat''s ear to transmit sound stimuli, while decreases in pressure had a very striking effect, particularly on the transmission of high tones. In prac tically every instance the high tones were lost com pletely. The standard of procedure was that the intro duction of the intralabyrinthine manometer needle should have no effect whatever upon the ability of the ear to transmit all tones and spoken voice normally, the normal having been previously established.