These are some risks associated with Cochlear Implant
Injury to the facial nerve: facial nerve goes through the middle ear to give movement to the muscles of the face. An injury during surgery can cause a temporary or permanent facial paralysis on the side of the implant.
Meningitis: cases found of meningitis after cochlear implant. People who have abnormally formed inner ear structure are at greater risk.
Tinnitus: ringing or buzzing sound in the ear.
Taste disturbance: the nerve that gives taste sensation to the tongue also goes through middle ear and might be injured during the surgery.
Loss of residual hearing: permanent loss of residual/remaining hearing in implanted ear.
Failure of the internal equipment: contact sport, accident, slips and falls near the ear can damage the implant.
May not be able to have MRI: MRI and some other medical examinations and treatments can not be done due to the presence of magnetic field.
Recipient will have to be careful of electrostatic field and devices.