Cochlear implant (CI) surgery has gone through a considerable expansion of the indications, varying from pediatric to elder adults nowadays. The otological surgeon must consider that anatomical variations are frequently encountered during cochlear implantation, especially in pediatric patients, and may complicate standard surgical approaches. Special consideration must be taken for those variations that may involve the jugular bulb, the sigmoid sinus, or middle cranial fossa dura and the facial nerve. Preoperative imaging plays a fundamental role in surgical planning and it may be of her in considering a subtotal petrosectomy (SP) in selected cases. This chapter presents key anatomical variants, their surgical implications, and illustrative case examples.