Approach to Internal Auditory Canal

The surgery of the internal auditory canal (IAC) represents a challenge for otolaryngologists and neurosurgeons because of the important anatomical relationships of this noble area with other structures, like the internal carotid artery and the facial nerve. Moreover, despite the benign nature of the vast majority of lesions located in the IAC, extensive surgical approaches are often required to reach that area, like transpetrous routes (e.g., translabyrinthine, transotic, transcochlear), the retrosigmoid route, and the middle cranial fossa techniques. All of these procedures are based on the use of the operative microscope and are defined “open techniques,” due to the extensive bone work, the brain or cerebellar retraction, or the facial nerve re-routing to reach the affected area. Since the introduction of the endoscope in the otologic field, there has been a progressive development in term of indications for transcanal endoscopic approaches. The advantages of endoscopic visualization and the possibility to work around the corner represent great advantages during ear surgery approaches. Recently, endoscopic techniques have been introduced also in lateral skull base surgery, either as assistance to microscope-based procedures or as an exclusive mini-invasive approach. In the latter case, the IAC can be reached via the external auditory canal corridor using an endoscopic transcanal transpromontorial approach. In daily practice, this surgical corridor is seldom employed, especially if specific diseases and the patient’s features are contemporarily present. However, the knowledge of the anatomy of the inner ear and the IAC from the external auditory canal corridor is important to be totally oriented during middle-ear surgery. The ovine model offers a suitable option to train with this procedure improving surgical skills and anatomical basics