The process of cochlear implantation

There are four steps to cochlear implantation: assessment, surgery, post-op switching on, and ongoing tuning.

Before surgery

If you are considering a cochlear implant you will need to be assessed by our surgeons and audiologists.

This assessment will determine if a cochlear implant may be of benefit and whether there are factors that might preclude implantation. This may involve several visits over a period of time to accurately assess your level of hearing and communication. An important part of this process is to ensure that the likelihood of benefit is high and that you are aware of all relevant factors. An opportunity will be provided for you to meet with people who have already received a cochlear implant and to share their experiences.

The operation

The surgical procedure is performed at St Andrews Hospital, located on South Terrace, Adelaide. The operation generally takes 2-3 hours and is performed under a general anaesthetic.

The Incision

A small amount of hair is shaved from the operation site and a curved incision is performed behind the ear.

Cortical Mastoidectomy

The skull behind the ear canal is called the Mastoid and contains a honeycomb of air pockets that connect through to the middle ear and the nose via the Eustachian tube. Using a drill these air pockets are opened up to expose the deeper structures.

Posterior Tympanotomy

In the deep part of the Mastoid are two important nerves, the Chorda Tympani (taste) and the Facial Nerve (facial movement). The bone between these nerves is gently removed allowing a direct view of the bone overlying the cochlea.

Bed Preparation

Further back on the skull a shallow recess is fashioned. The receiver stimulator part of the implant will sit in this recess at the end of the operation.

Cochleostomy

Usually a hole 1 to 1.5 mm (depending on the type of electrode being used) is then created through the bone of the cochlea to enable access to its chambers. In some cases, especially with a Hybrid electrode, the electrode is inserted via a membrane in the cochlea called the round window.

Implant Insertion

The electrode array is gently inserted into the cochlea. An additional ground electrode is tucked under a nearby muscle and the implant fitted to recess in the skull bone.

Closure

The wound is sutured closed in layers and a bandage fitted around the head.

Following surgery

You will stay in hospital for 1 to 2 days. Occasionally a longer stay is needed if you experience problems such as dizziness. Patients are not discharged from hospital until they are well enough to go home. An X-ray is usually taken the day after surgery to check the position of the implant.

You will see your surgeon approximately one week after the operation to check your progress and to remove the sutures.

During or shortly after the surgery a “Telemetry” check is performed to ensure the device is working as expected. Several weeks are then allowed for healing to occur prior to beginning the switch-on process. The switch-on process involves around ten visits lasting 1-2 hours each with our audiologists over a 4 week period to tune the cochlear implant to your changing requirements. The aim is to fine tune the implant to maximize the amount of useful sound information you receive.

Ongoing Tuning

An average of 2 to 3 visits a year are required for ongoing tuning. Many recipients report changes and indeed improvement in their hearing over several years, hence the need for ongoing care.