- WHAT ARE ITS COMPONENTS ?
- PREOPERATIVE ASSESSMENT ?
- SURGICAL TECHNIQUE ?
- POST OP STAY & FOLLOW UP ?
- REHABILITATION ?
- evaluation of hearing
- communication ability
- cochlear morphology
- middle ear and mastoid status
- general developmental issues
AUDIOLOGICAL TESTS :
- Auditory brain stem implant (ABR) or electrocochleography (ECochG).
- behavioral testing – using tests such as visual response audiometry.
- older children with post lingual deafness, standard pure tone and aided free field tests are performed along with speech discrimination .
- An aided audiogram.
PSYCHOLOGICAL ASSESSMENT AND PREOPERATIVE COUNCELLING :
The purpose of this is :
- To determine the intellectual ability of the child
- Identify family issues that may affect implantation and post implant performance.
- Ability to assist in the delivery of an intense postoperative programme to enable the child to develop receptive and expressive oral language skills.
- Assessment of both the recipient’s and his/her family expectations for the device. If expectations are unrealistic, they can be modified prior to implantation.
Advanced Bionics Devices(USA)
Surgery under general anesthesia is required to implant the internal components. The receiver / stimulator assembly is placed inside the temporal bone and the electrodes are inserted into the cochlea, which in turn directly stimulates the hearing nerve. The implantation procedure usually takes about one to two hours.
Mapping & Switch On :
After three to four weeks the incision should be healed. At this point, the programming of the speech processor will be carried out and the external parts of the implant will be hooked up. The implantee will begin to hear then.
Auditory Verbal Therapy :
Children who are not exposed to the hearing world must undergo extensive habilitation to improve their speech, language and hearing skills.
POST OP CARE :
Hospital stay – 5 days
Single parenteral antibiotic
Implant activation – 21st post-op day
PER OP NRT :
Before closure of the post aural incision place the magnetic coil over the receiver stimulator to record NRT & measure impedence of electrodes.
Although complete electrode insertion is desirable but atleast 8-12 electrodes should be inserted atraumatically to achieve good post op rehabilitation & speech therapy.
HOSPITAL STAY :
Dressing is done and patient put on single 3rd gen cephalosporin for 10 days. Dressing is opened after 48 hrs and looked for soakage or any evidence of edema /hematoma at the incision site.
The patient is discharged on 3rd day with the wound left open and planned for ‘switch on’ on the 21st day.
Athough there is no criteria about the day of switch on , but one waits till the post aural edema subsides down so that the coil adhers well to the receiver /stimulator.
OUTCOME PREDICTORS :
Length of auditory deprivation – the best age of implantation is between 2 – 4 yrs , before Neural plasticity is lost.
Although US FDA has given cleareance for implantation in less than 1 yr child.
Although FDA has approved the use of cochlear implants above the age of 12months, surgeons may go “off label” and implant children younger the 1year. This includes children with medical necessity such as those who have been deafened by meningitis and present with ossifying cochlea before the age of 12months7.
OUTCOME PREDICTORS-CHILDREN :
Age at time of implantation – it is the most important predictive factor for the speech & language skills of an implanted child.
Strong emphasis in auditory and oral speech input.
FOLLOW-UP REQUIREMENTS :
Return for re-mapping in 3-4 weeks of initial hook-up.
Return every 1-3 months for re-mapping and speech perception testing during the first year.
Return at 6 months for fine tuning.
Return every 6 months to one year for follow-up.
- Necessary part of implantation.
- Different focus depends on patient’s previous experience with sound.
- Goal is to enable children to be able to learn passively from the environment.
- Program addresses receptive as well as expressive language skills.
- Multidisciplinary, dedicated group necessary.