The transventricular approach through a transcortical approach or a transcallosal approach allows access to the third ventricle with transforaminal, subchoroidal, or transfornician approaches. The usefulness of these approaches have been reported for intraventricular tumor removal 1) 2) 3) 4) but there is a risk of injuries to the surrounding neuronal or vascular structures, such as the body of the fornix.
In 1958, Niemeyer described a more selective approach to the hippocampus and amygdala through the middle temporal gyrus 5).