ABSTRACT
The ability to restore hearing function for the profoundly deaf by direct electrical stimulation of the auditory nerve is one of the most important advances in medical science to date.
It is made possible using an implanted intracochlear electrode array. In profoundly deafened human adults, unlike other species, the auditory nerve survives and remains viable for many years. In congenitally deaf infants, cochlear implantation is also very successful, but only if implantation occurs before the age of 4. After this, if the cortical language centres receive no stimulation, they lose the ability to organize and function. The currently agreed optimal age of implantation in the United Kingdom is around 1 year, though in other countries, such as Canada, implantation is routine in children as young as 6 months. Below this
age there are still doubts about accurate diagnosis of profound deafness and the safety of surgery, though this may change as technology improves.
