The cribriform plate is enclosed between the two medial orbital walls extending anteroposteriorly from the crista galli to the planum sphenoidale. During the nasal phase, the anterior attachment of the nasal septum is detached from the skull base according to the exposure needed. Prior to performing the bone opening, all the soft tissues have to be resected and eventually all feeders branching off nasal vessels could be isolated and coagulated. Bilateral removal of the cribriform plate is achieved with a 3-mm diamond burr high-speed drill in a rostrocaudal direction up to the medial orbital walls. Early tumor devascularization is achieved upon identification and coagulation of the anterior and posterior ethmoidal arteries129; on the contrary, eventual uncontrolled bleeding can cause retraction of these arteries with a retrobulbar hematoma.