The rate at which isotopes descend from the cisterna magna to the lumbar subarachnoid space is highly variable. In monkeys, with and without previous lumbar puncture, transit time was measured. In animals with a previous lumbar puncture, transit times were 10 to 120 minutes; in monkeys without a previous lumbar puncture, transit times were 120 to 180 minutes, in experimental studies of cerebrospinal fluid circulation, the effect of lumbar puncture must be controlled.
展开▼