Cochlear Implant Surgery

Cochlear implant surgery is usually performed as on an out-patient basis, and is usually a fairly minor procedure to undergo. It is performed under general anesthesia and takes about 1.5-2 hours. The site of the internal receiver is first planned out and drawn on the skin. The incision is then planned and performed. The bed for the internal receiver is prepared, and small holes are drilled in the skull to allow the device to be secured to the skull. The mastoid bone is then opened, and the middle ear is then entered. The round window is opened, and a tiny hole is made in or near the round window to enter the cochlea, which is called a cochleostomy. The implant’s electrode array is then inserted into the cochleostomy. A few tiny pieces of muscle are inserted around the electrode array to seal the hole and the wire is placed in the mastoid. The internal receiver is sutured to the skull. The incision is closed and the integrity of the device is sometimes checked with electrical equipment and an x-ray is sometimes ordered to confirm the position of the device in the cochlea. A dressing is wrapped around the head.

The patient recovers for a few hours in the hospital and when he is able to walk independently, he is discharged home. Oral antibiotics are used for one week, and pain pills are prescribed, although most patients are comfortable with over the counter medications for pain control. The dressing is removed by the patient the next day, and sleeps on the opposite ear for one week. Attention has to be taken to not wear tight-fitting glasses, and contact sports need to be postponed for a month. The patient may shower the next day.

The incision is allowed to heal for 2-3 weeks before the device is activated. The patient then returns to the office for activation of the device. During the initial activation, the patient learns about the care and function of the external component of the implant. The channels are checked and an initial map, or program, is installed. The patient returns again a few days to one week later for more adjustments. Refinement of the program allows him to eventually hear more clearly with time. Several different programs are usually installed to allow the patient to have different programs for different listening conditions. The patient is monitored over time and “remapped” as he gets used to the noises of the world returning to his life.

Surgery in babies and young children is usually performed on an in-patient basis, but the stay in hospital is usually only for observation for one night. Care must be taken to avoid the child from touching the incision or banging the head during play or a fall. A dressing is frequently kept on for a few days, and a small hat is recommended to keep fingers off the incision.

Loss of residual hearing
Cochlear implant surgery by nature involves trading a patient’s acoustic poor hearing in for hearing with an electronic device. There is frequent loss of all residual hearing in the ear, so that a regular hearing aid will no longer benefit the patient. In many instances, some residual hearing is maintained, but this can not be relied upon.
Failure to benefit
there is a small risk that the patient will be disappointed in the hearing that is obtained following cochlear implant surgery. Careful detailed analysis is performed prior to surgery to insure patients will not be disappointed that they have sacrificed their acoustic hearing. Less than 5% of patients are dissatisfied with the results of this surgery.
Device failure
the device can fail or stop working in a small number of patients. These rates vary with the device implanted, but are usually less than 2%. This failure can come soon or many years after surgery. The failed device can usually be successfully replaced with revision surgery.
Infection
Infection is a potential infection of any surgery. Severe infection after cochlear implantation can result in extrusion, or removal of the device.
Cochlear implant candidates are at an increased risk of contracting meningitis after surgery. All implant candidates require vaccination for Streptococcus pneumonia at least 2 weeks prior to surgery.
Facial nerve paralysis
this is a rare complication of surgery
Taste change or loss
this can occur after surgery and cause a lack of taste, or change in taste on the side of the tongue. Taste problems can be more serious in patients undergoing bilateral surgery
Dizziness
few patients experience problems with dizziness or imbalance after surgery. It can be severe in a patient with balance problems prior to surgery.
Tinnitus
this occurs in about 50% of patients after surgery but usually resolves over time. Less than 5% complain of dizziness after 1 year. Tinnitus can frequently improve after implantation and is sometimes considered in choosing which ear to implant.


A "mini" Incision	external processor


The round window membrane	The cochleostomy - the round window has been drilled open	The electrode array inserted into the cochleostomy

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