Use of radio-iodinated serum albumin in the study of cerebrospinal fluid flow

The evidence which has accumulated over the last 15 years from the use of radio-isotopes in the investigation of cerebrospinal fluid production, flow, and absorption indicates that, whereas small molecules and ions are exchanged between the cerebrospinal fluid and the systemic circulation at a very high rate, the disappearance of protein from the lateral ventricles is primarily dependent upon a relatively slow flow through the classical pathway to the sites of absorption (Sweet, Brownell, Scholl, Bowsher, Benda, and Stickley, 1954). The dis-appearance half-time (Ti) of 1131 albumin from the lateral ventricles is grossly prolonged in hydro-cephalus, and this observation has been used more recently as the basis of a quantitative method for the diagnosis of this condition (Atkinson and Foltz, 1962; Atwell and Scott, 1966). The movement of protein through the cere-brospinal fluid pathway can be studied graphically, using a scintillation counter and serial scanning to detect the sites of maximal gamma emission after the injection of radio-iodinated serum albumin into the ventricles (Di Chiro, 1964)-a technique known as RISA ventriculography. By this method the bulk movement of the labelled protein is clearly demon-strated and, in the normal adult, the RISA reaches the basal cisterns in 1 hr, the Sylvian fissure in 3 hr, the cerebral convexity in 12 hr, and by 24 hr the remaining emission is alongside the sagittal sinus (Di Chiro, 1966). This communication is a preliminary report on the use of RISA in the investigation of various conditions with which alterations in the cere-brospinal fluid dynamics are associated. The purpose of the investigations was, firstly, to assess the reliability and place of certain procedures using this radioisotope in the diagnosis of hydrocephalus, in order to plan surgical treatment, particularly in infants, and, secondly, to see if these methods would give a fuller picture of the behaviour of cerebrospinal fluid in various pathological condi-tions