Measurement of Total Cerebrospinal Fluid Formation Proximal to an Acute Cisternal Block

The posterior fossa and adjacent supratentorial subarachnoid cisterns of dogs were obstructed with Lipiodol Ascendant. This oily radiopaque material was introduced through a needle in the cisterna magna. The cerebrospinal fluid formed proximal to the cisternal block was collected by draining it from the cisterna magna at the original cisternal pressure and at zero pressure. The rates of formation of cerebrospinal fluid recorded at both pressure levels (0.053 ml/min. at initial pressure; 0.049 ml/min. at zero pressure) correspond well with cerebrospinal fluid measurements made by other methods.