Vertical Digitation of the Hippocampus: An Intraventricular Landmark for Amygdalohippocampectomies

Duvernoy's vertical digitation of the hippocampus (VDH) forms the medial wall of the temporal horn anterior to the inferior choroidal point. Although it is inevitably resected in all the classical techniques, as it is the key for disconnecting medially the temporal lobe from the central core, it is seldom mentioned in the literature as a reliable alternative intraventricular landmark for guiding amygdalohippocampectomy. The primary objective is to provide a detailed and focused technical note describing how this landmark is safely used for amygdalohippocampectomies.

We describe the anteromedial temporal resection technique used by the authors, and characterize anatomically and histologically the VDH. We analyzed 5 cadaveric specimens and examined histologically a resected VDH tissue from a representative patient with epilepsy to precisely describe the proposed anatomic landmark.

The VDH facilitates precise identification of the superior amygdalar boundary, helping to avoid damage to critical structures such as the globus pallidus or the optic tract. On its extraventricular aspect, the VDH marks the posterior limit of the semilunar gyrus. This gyrus houses the cortical nucleus of the amygdala and is covered by archicortex, specifically the piriform cortex. Achieving seizure freedom relies on key technical principles, including complete removal of the amygdala-encompassing the piriform cortex, also known as the "the area tempesta"-and hippocampal resection extending posteriorly to the quadrigeminal plate.

Our findings support the VDH as a practical anatomic reference for ensuring complete and safe anteromedial temporal resection. This landmark enhances surgical precision, particularly in cases where traditional references are inadequate, and improves the reproducibility of amygdalohippocampectomy techniques.