Comparison of electrical resistance, bubble withdrawal, and stereotaxic method for cannulation of cerebral ventricles

A comparison was made of three methods of lateral intraventricular (LV) cannulation in the rat brain. Rats in a control group (n = 8) were cannulated using traditional stereotaxic coordinates. In a second group (n = 8), electrical resistance was used to localize the ventricle and differentiate it from surrounding brain areas. In a third group (n = 8), a bubble withdrawal technique was employed where movement of a bubble in polyethylene tubing was monitored as the cannula was lowered in brain. All three methods produced accurate LV cannulation, but the electrical resistance technique was associated with optimal placement within the LV. Using the resistance procedure, greater access was obtained to posterior portions of the ventricular system. Also described is a novel stereotaxic cannula holder that may be used in the bubble withdrawal procedure or in obtaining acute samples of cerebrospinal fluid.