Pneumoencephalographic Study of Cerebrospinal-Fluid Absorptive-Block Mechanisms

DESPITE extensive research, the factors concerned with the dynamic equilibrium of cerebrospinal fluid are but imperfectly understood. Theories on the formation of cerebrospinal fluid consider the possibilities of dialysis, ultrafiltration,1or a secretory process, the last theory being supported by more recent data.2The site of formation of cerebrospinal fluid also remains in doubt. Earlier theories centered it in the choroid plexus,3while recent studies suggest that the cerebrospinal fluid is formed more diffusely in all perineuronal and perivascular spaces.4Physiological mechanisms influencing the formation of cerebrospinal fluid and abnormal factors capable of altering its formation remain even more obscure. Although the anatomical pathways of cerebrospinal-fluid circulation are known,5a thorough investigation of the pathological conditions which may block these channels and of the resultant effects of such a block mechanism has not been made. Likewise, the absorptive bed and physiological factors concerned with absorption