Tonsilla cerebelli - anatomy, function and its significance for neurosurgery

Abstract

The goal of our work was to acquaint the reader -neurosurgeon with the detailed anatomy of the cerebellar tonsil, focusing on its individual surfaces. This is because, in most publications, the tonsil is presented only within the context of the anatomy of the entire cerebellar hemisphere, or possibly the anatomy of the cerebellomedullary fissure or the course of the arteria cerebelli posterior inferior. We conducted cadaveric dissections of the tonsil on 4 cerebellar hemispheres (divided sagittally in the plane of the vermis) and on one complete cerebellum with its peduncles and the floor of the fossa rhomboidea. We used this for demonstrating the telovelar approach. We believe that for the safe mastering of the telovelar approach in the operating room, laboratory dissection is mandatory. It allows the neurosurgeon to recognize even less known structures of the lateral recess, cerebellomedullary fissure, and understand the telovelar junction. In a comprehensive review, we also document individual surgeries related to the tonsil and telovelar approach: the surgery for Chiari malformation with syringomyelia, tumor of the IV th ventricle, cavernoma of its lateral recess, and cystic hemangioblastoma of the medulla oblongata. Based on literary data, we document the history of the surgical approach, which is an exemplary demonstration of the collaboration between two world-renowned neurosurgeons (Rhoton and Matsushima), and was underpinned by extensive laboratory work. In the review, we address congenital variants of cerebellar tonsil herniation (Chiari malformation) as well as secondary causes and their imaging possibilities. We mention the clinical significance of the pathological descent of tonsils and their association with syringomyelia.