Resection of Ependymomas Infiltrating the Fourth Ventricular Floor: Anatomosurgical and Stimulation Mapping Techniques

Despite the importance of complete, gross total resection (GTR) of fourth ventricular ependymomas, significant morbidity and/or subtotal resections are reported, particularly when the ventricular floor is infiltrated. Step-by-step technique descriptions are lacking in the literature.To describe monitoring and stimulation mapping techniques and surgical nuances in the challenging subgroup of infiltrating fourth ventricular ependymomas by a highly illustrated, step-by-step description. Superimposed outlines of cranial nerve nuclei on the surgical field demonstrate critical anatomy and facilitate understanding in a way not previously presented.We reviewed the microanatomical and neurophysiological prerequisites of resecting a diffusively infiltrating fourth ventricular ependymoma.We achieved GTR with the use of reproducible stimulating mapping and accurate cranial nerve nuclei identification.Enhanced microanatomical understanding, reproducible stimulation mapping, and meticulous resection techniques can result in GTR, even in diffusively infiltrating ependymomas.