Many different specific situations (anatomical variations, advanced otosclerosis, labyrinthitis and meningitis, simple chronic otitis and cholesteatoma, ear malformations, temporal bone fractures, intracochlear  neurinomas and other rare situations) may represent a challenge to perform a cochlear implantation. Surgical treatment of these unusual cases requires experience and skill in the otologic and sometime in the lateral skull base field. To overcome the difficulties of the cases  very often a different approach is required, mainly the subtotal petrosectomy. The Authors will discuss the problems related to every single situation showing practical case and sharing their experience in the field.