Cochlear Implantation

What is a Cochlear Implant?

It is a surgically implanted device, which provides hearing sensation to the patients who have severe to profound deafness and who gets either no or little benefit from hearing aid.

It bypasses the damaged part (hair cells) of the inner ear and sends electrical stimulation to the nerve ganglions and the hearing nerve, which is then interpreted as sound, by the brain.

Pre Operative Work up or evaluation for Cochlear Implant

Detailed work up is very essential part before proceeding for any surgery and in cochlear implantation this becomes more important as future of the child depends on the result of the surgery and habilitation and also the cost involved is not less.

In general work up should include:
  • Evaluation of hearing (Audiological Evaluation)
  • Psychological Assessment
  • Radiological Assessment
  • Other Evaluations if required

There is no single test, which can assess the hearing status of child properly, so battery of tests are implied to have proper assessment as the decision of the intervention will depend on this evaluation. The tests that are commonly used are:

  • Behavioral Observational Audiometry/ Pure Tone Audiometry
  • Aided Audiometry
  • Auditory Steady State Response (ASSR)
  • Brain Stem Evoked Response Audiometry (BERA)
  • Oto Acoustic Emissions (OAE)
  • Tympanometry

This will help in determining the hearing thresholds and also will evaluate whether the child will get adequate benefit from hearing aid. This means the hearing benefit, which can lead to development of speech and language.

IQ testing and also evaluation to know whether the development of the child is age appropriate or there is any delay in the development. The evaluation should also be done to know the spectrum of autism or hyperactivity.

It is mandatory to know the status of the inner ear and hearing nerve. It is also important to know whether the anatomy of middle ear and inner ear is normal or there is some anomaly, which is present. This is important because in certain anomalies cochlear implant cant be done like cochlear aplasia or absence of hearing nerve.

HRCT scan of temporal bones
MRI of inner ear with 3D reconstruction of cochlea

These two are mostly required to assess the feasibility of cochlear Implant.

There are certain other evaluations which may be required as the deafness may be a part of some syndrome, so depending on the syndrome eye check up, cardiac evaluation, kidney assessment , Neurological evaluation etc may be required.

Post operative care and Hospital stay

After the surgery the patient is put on intravenous antibiotics for 2 days and after that it is changed to oral antibiotics at the time of discharge from the hospital. The antibiotics are generally continued for 10 days along with some pain relieving medicines for initial 3-5 days.

Post operatively patient stays in the hospital for two. On the first post operative day X-ray of the mastoid region is done for the documentation of the implant position.

On second day dressing is removed and wound is checked for any swelling, infection, hematoma or any collection of fluid. Fresh dressing and bandage is applied under aseptic and sterile conditions. The patient is discharged on the second post operative day with certain precautions which have to be maintained. Suture removal is done between 8-10 days after the surgery.

Earlier switch on of the device was done after 3weeks but now studies have shown that one can do early switch on that is it can be done just after suture removal also.

In case of emergency like if patient gets cold or some trauma occurs at the site of implant then patient’s attendants can directly contact the doctor.