Evaluation of Photoscanning of the Diffusion of Intrathecal RISA in Infantile and Childhood Hydrocephalus

HE limitations of pneumography for delineation of available extraventricular subarachnoid space have encouraged us to examine the use of radioactive isotopes. The rate of diffusion and distribution of an confined to this space could permit, by external scanning, an estimation of cerebrospinal fluid (CSF) distribution and dynamics. In contrast to pneumography, the procedure would not simultaneously disturb the CSF dynamics, and information so derived might be useful for assessing the severity and progress of hydrocephalus. The physiological basis rests upon the observations of Sweet and others, r,8 namely, that labeled protein is confined to the CSF space and, by diffusion and directional flow, passes over the hemispheres ultimately into the venous system along the major sinuses. The first clinical applications were for demonstration of spinal blocks. 2,6 Later, DiChiro, with others, 4,5 developed methods for demonstrating CSF fistulas, arachnoid cysts, porencephaly, and hydrocephalus, and introduced the term isotope cisternography, which has been generally adopted. Currently the technique is being tried in studies of communicating hydrocephalus in adults. 1,~ Our investigations were to assess the possible diagnostic usefulness in childhood and infantile hydrocephalus by correlating the isotopic findings with the degree and progression of the hydrocephalus as determined by previous pneumography, ventriculography, and clinical parameters. Some of the children were studied before and following insertion of ventriculoatrial shunts. Our experience so far includes 51 scans in 45 patients. The majority of these patients had hydrocephalus (28 infants and children, 12 adults) but we also included cases of pseudotumor cerebri, CSF rhinorrhea, and adult cerebral atrophy.