Transcanal infrapromontorial approach for internal auditory canal surgery and cochlear implantation.

Objective: To demonstrate the feasibility of a transcanal infrapromontorial approach for vestibular schwannoma surgery through an anatomical dissection study and the description of a clinical case. Methods: A microscopic and endoscopic dissection of cadaveric heads was undertaken through a transcanal infrapromontorial approach to the internal auditory canal (IAC), preserving the cochlea and the cochlear nerve. Description of the anatomy and surgical steps is reported as well as presentation of a clinical case in which a transcanal infrapromontorial approach was performed. Results: In all of the cadaveric dissections, a transcanal infrapromontorial route with near total cochlea preservation was performed, removing only the most posterior portion of the basal turn of the cochlea. The IAC was opened through removal of "cochlear-vestibular bone". At the end of the dissection a cochlear implant array was placed. A transcanal infrapromontorial approach was also performed in a patient to allow a concurrent cochlear implant placement, with good postoperative results. Conclusion: The transcanal infrapromontorial approach permits the preservation of the cochlea and the cochlear nerve. This approach may be considered as an option in case of a small intracanalicular schwannoma removal (< 0.5 cm cerebellopontine angle spread), when concurrent cochlear implantation is indicated.