Cochlear Implant Evaluation And Selection Procedures

Information For Candidates And Families

The Assessment

There is no minimum or maximum age for referral to the Cochlear Implant Programme.

The first important step along the path to cochlear implantation is undergoing an extensive and thorough evaluation process to determine likely benefit from the surgically implanted hearing device. Because an operation is involved and the commitment of resources and time is intensive for both candidates and the Cochlear Implant Clinic, there are a number of criteria which must be met before an individual will be considered to be a good potential cochlear implant user. The selection criteria for cochlear implant candidates are:

  • Severe to profound bilateral sensorineural hearing loss
    OR
  • A moderate to severe sloping sensorineural loss which is deteriorating
  • Optimally fitted hearing aids should have been worn and monitored for a minimum period, usually 12 weeks
  • Aided responses and speech perception measures should suggest likely benefit from a cochlear implant
  • There should be no medical or radiological reasons for not proceeding with cochlear implant surgery or habilitation. Any impediment to the placing of the cochlear implant device into the appropriate position will be evaluated by appropriate radiology (CT scan or MRI imaging) and the implications must be accepted by all involved
  • The candidate / candidate's family must demonstrate a commitment to the intensive pre and post implant habilitation programme, which will be determined by the Habilitation Co ordinator and agreed upon by all involved
  • The candidate / candidate's family must demonstrate appropriate expectations and understand the potential and limitations of a cochlear implantThe candidate / candidate's family must demonstrate a commitment to the development of the child's communication skills through an oral/aural approach

An evaluation process will take place over a minimum 12 week period (less under special circumstances) which is sometimes referred to as the “Hearing Aid Trial” or HAT. During this time, a full battery of audiological tests will be carried out. These include repeated aided and unaided audiograms, otoacoustic emissions, electrophysiological tests, impedance audiometry and speech perception tests. An important component in the assessment process is the radiological investigation of the cochlea. Arrangements will be made to undergo CT scans of both temporal bones under a light general anaesthetic. This enables the surgeon to see the formation and suitability of the cochlear for implantation.

If there is any question about the status of the auditory nerve, and MRI scan may also be required in order to obtain important information about neurological status.

An evaluation will be performed by the Cochlear Implant Team Surgeon, who will investigate the history and cause of the hearing loss, review the radiology scans and reports and assess the presence of any medical or radiological contraindications to cochlear implant surgery.

During the course of the assessment process for children, the Habilitation Co ordinator will evaluate the child’s communications abilities and devise a habilitation plan to be agreed upon by all parties including the family and any educational agencies which may be involved. The child’s current levels of auditory functioning, and speech and language skills will be assessed. The Habilitationist will also work with the child to establish stimulus response skills for the purpose of pre-operative audiological evaluation and post-operative programming of the cochlear implant device.

An appointment may be arranged with the Cochlear Implant Team Psychologist / Family Counsellor. This will give the child and family further opportunity to discuss any concerns or problematic situations. The Psychologist / Family Counsellor may be able to provide helpful input into coping with the impact of hearing loss and its impact upon family dynamics.

Guideline Audiograms:

 

 The Descision

At the end of the evaluation process, a final meeting will be held to decide likely benefit from a cochlear implant.The Assessment Review Decision (ARD) meeting brings together all parties involved in the evaluation process, including Team Surgeon, Audiologist, Habilitationist, and Psychologist/ Family Counsellor if involved and the candidate / candidate’s family. Once the decision has been agreed upon by all parties, the candidate will be:

  • Approved, and awaiting funding confirmation
  • Discharged from the Programme
  • On Review if the hearing loss is not severe enough but is known to be deteriorating

If a decision has been taken not to go ahead with a cochlear implant, arrangements will be made to ensure continuing audiological support. If the decision has been taken to proceed, in some cases funding may be available within a short period of time, or it may be necessary to go on to a waiting list for allocation of funding. The funding allocation is decided at monthly Clinical Committee meetings and as there is a limit on the amount of funding available through the public health system, a waiting period may be necessary.