CANNULATION OF A LATERAL VENTRICLE IN THE BRAIN OF HOLSTEIN CALVES

A surgical technique was developed for implanting a flexible polyureth ane cannula in a lateral ventricle in the brain of calves. Initially, measurements were made on 25 calves at necropsy to develop equations f or calculating coordinates for cannula placement. The distance (cm) ca udal, in the sagittal plane, from the coronal suture line to the cente r of a hole to be drilled in the parietal bone of the skull was: 0.73 + (0.00925 x body weight [kg]). The distance (cm) lateral from the mid line to the center of the hole to be drilled was: 0.018 + (0.6464 x di stance caudal) The depth (cm) from the surface of the skull to the dor sal surface of the lateral ventricle was: 2.29 + (0.0159 x body weight [kg]). Surgery was subsequently performed on 17 calves. A 5-mm-diamet er hole was drilled through the skull with a hand trephine at coordina tes derived from the aforementioned regression equations. A polyuretha ne cannula (total length, 30 cm; 1 mm ID; 2 mm OD) covering a stainles s-steer 20-gauge blunt-tipped needle (stylet) was lowered through the brain and into a lateral ventricle at an angle of 20.5 degrees relativ e to the frontal bones of the skull. The blunt-tipped needle was then removed, and CSF was allowed to drip from the cannula to verify placem ent. One stainless-steel screw was inserted 0.6 cm medial, and another was inserted 0.6 cm caudal to the hole in the skull. The area around the cannula, bone screws, and hole in the skull was covered with denta l acrylic (approx 2 cm in diameter) to stabilize the cannula. With min imal restraint of calves, injection of substances into and withdrawal of CSF from a lateral ventricle of the brain were possible in most cal ves for at least 6 weeks after surgery was performed.