MODIFIED TECHNIQUE FOR THE SELECTIVE PERFUSION OF THE 4TH CEREBRAL VENTRICLE IN CONSCIOUS DOGS

A method is described which permits selective and repetitive perfusion of the fourth cerebral ventricle in the conscious dog. An inflow needle is introduced stereotaxically at an angle of 42°-44° through the occipital bone and the cerebellum until its tip reaches the ventricular space. The outflow guide needle is placed vertically above the cisterna cerebello-medullaris. Later a matching outflow needle is introduced through the guide needle, punctures the atlanto-occipital membrane and drains the cisterna magna. A retaining ring with a set-screw, which fits into the hub of the guide cannula, is used to adjust the outflow needle in the vertical plane. The inflow needle and outflow cannula are fixed permanently in place with the aid of a kneadable solidifying dough (Technovit) to two self-threading screws at the external protuberance. In a separate study fentanyl perfused through the fourth cerebral ventricle in increasing concentrations (2.5, 5, 10, and 20 μg/ml) induced a dose-related hypotension, bradycardia, and electroencephalograph-synchronization. These effects could be reversed by subsequent naloxone (20 μg/ml) perfusion. © 1979.