Ventral brainstem anatomy: An endoscopic transoral perspective

In recent years the use of the endoscope through the transclival route has gained new attention as a minimally invasive operative method to successfully treat numerous clival pathologies such as chordomas, meningiomas, haemangiopericytomas, enterogenous and epidermoid cysts, and metastasis(Cappabianca et al. Neurosurgery 55:933–940, 2004; Cappabianca et al. Childs Nerv Syst 20:796–801, 2004; Cappabianca et al. Adv Tech Stand Neurosurg 33:151–199, 2008; Cappabianca et al. Neurosurgery 49:473–475, 2001; Cappabianca et al. Surg Neurol 62:227–233, 2004; Dehdashti et al. Neurosurgery 63:299–307, 2008; Kerschbaumer et al. Spine (Phila Pa 1976) 25:2708–2715, 2000; Saito et al. Acta Neurochir (Wien) 154:879–886, 2012; Stippler et al. Neurosurgery 64:268–277, 2009). Here we describe the endoscopic anatomy of the region reached through an endoscopic transoral approach. Fresh and formalin-fixed cadaver specimens were used to demonstrate both the feasibility of an endoscopic transoral–transclival intradural approach and its potential exposure. The transoral approach was performed using a clival opening of 20 × 15 mm. This smaller access point through the clivus, which allowed insertion of the endoscope and its instruments, did not limit the complete exposure of the cisternal spaces and permitted reconstruction of all anatomical layers. This endoscopic approach thus provides excellent exposure of some of the most dangerous and inaccessible territories of the brain, respecting the anatomy and remaining a minimally invasive approach. Further extensive clinical experience is necessary to prove its safety. The endoscopic transoral–transclival approach will presumably be selected to gain access to lesions of the lower ventral brainstem and the surrounding cisternal spaces, with development of new and more efficient surgical strategies for dural and bone defect repair.