Cognitive function is a complex brain function that is important in the cognition of the reality and connecting with it. It has a complicated reflex basis, arises from external factors exposure, improves by growing up and learning till its maximum and declines in the elderly age. For several years it was believed that cognitive function drop is connected with ageing processes of the whole organism. However, the results of the latest studies show that it can be affected by many factors. Two of the most influencing factors are hearing and vestibular efficiency. Moreover, hearing and vestibular normalization can even improve the cognitive function. Unfortunately, studies, that describe the role of hearing and vestibular function in the cognitive sphere, are extremely rare. That is why further research is very important, especially in the rehabilitation tactics. For elderly patients with severe-to-profound hearing loss cochlear implantation is the optimal rehabilitation method. However, ear surgery can lead to such complication as vestibular dysfunction. That is why preoperative diagnostics and postoperative care are very important for preventing cognitive impairments.