Cannulation of the cisterna magna in sheep: a method for chronic studies of cerebrospinal fluid.

A method of cannulating the cisterna magna of sheep is described. Successful cannulations were achieved in 15 of 17 attempts (88%). Mean cannula patency was 13.9 days (range 7-20). Using these cannulas, it was possible to obtain samples of cerebrospinal fluid (CSF) in large volumes (4-8 ml) and remove 20-30 ml of CSF over a 5 h period. This technique allows access to the CSF of an animal large enough for the removal of samples of CSF of sufficient size to detect materials present at very low concentrations.