Cochlear Implants
THE PROBLEM OF HEARING IMPAIRED CHILDREN IN INDIA
Screening of new-born infants for hearing defects :
In most developed countries, hearing assessment of the new-born child is mandatory, as it has been categorically proved beyond doubt that in cases of hearing impairment at birth, immediate intervention is ESSENTIAL in order to permit the development of speech and hearing.
THE AGE-OLD CONCEPT OF WATCHFUL WAITING - " It shall improve in the next few years " IS TO BE CONDEMNED!
WE HAVE A FULLY EQUIPPED PEDIATRIC HEARING ASSESSMENT FACILITY. We have state of the art equipment and hearing aid facilities that permit effective hearing rehabilitation of hearing impaired children and adults.
At our Clinic we are well aware of the problems faced by mothers in bringing the new born infant into a hospital environment, concerning the practical problems as well as the emotional trauma caused in the highly emotionally delicate state of the new mother.
What this involves :
At a convenient hour, the audiologist along with a qualified ENT surgeon shall review the patient. Initial screening involves a brief examination of the ear and a tympanometry test to assess the middle ear. This is followed by Otoacoustic Emission test. This is the global screening standard.
It is reported as " Pass " or " Fail ".
If the infant were to fail the test, a BERA and ASSR test would be immediately conducted after a telephonic consultation with the pediatrician if necessary. It is mandatory for the child to remain absolutely still in order to give a reliable report, thus occasionally necessitating the need for sedatives. This is administered by a pediatric anesthesiologist.
ASSR Compared to ABR (BERA)
The ability to detect differences in these significant hearing loss categories is very important. For example, differentiating a 75 dB versus a 95 dB hearing loss may impact decisions such as fitting traditional hearing aids on a child with a 75 dB SNHL, or considering cochlear implant options for a child with a 95 dB SNHL.
The ASSR is characterized by a number of clinical advantages. One clinical advantage alone - the capability of electrophysiological estimation of auditory thresholds of up to 120 dB HL in infants and young children - has guaranteed the ASSR a secure place in the pediatric test battery. ASSR thresholds are within 10 dB to 15 dB of audiometric thresholds.
Potential advantages of ASSR
- Frequency-specific signals are employed for estimation of auditory sensitivity at audiometric frequencies.
- Frequency-specific auditory information can be obtained with air - or bone-conduction signals.
- Signal intensity levels can be as high as 120 dB HL. The ASSR is, therefore, useful for electrophysiologic assessment of severe to profound degree of hearing loss in infants and young children.
- Automated response detection and analysis (ie, experience in waveform analysis is not necessary).
ASSR testing provides audiometric information that is essential in the management of children with severe-to-profound hearing loss. American Journal of Audiology Vol.12 125-136 December 2003.
In case a problem is detected, IMMEDIATE rehabilitation with hearing aids is offered. If there is no objective difference in the child’s response in a few months, a COCHLEAR IMPLANT is offered.
What is a cochlear implant?
A cochlear implant is an operatively placed hearing prosthesis designed to restore or provide a level of auditory sensation to adults and children who have a severe to profound bilateral sensori-neural hearing impairment and who get limited benefit from hearing aids.
This device consists of 2 components, an implantable device and an external receiver-stimulator, which looks like a large hearing aid.
A deaf-mute person NEED NOT remain so!!
Only 10% of deaf-mute children cannot be helped
90% can gain sufficient communication to be near normally integrated in society
An educated person will have contributed an average of Rs.1,00,00,000 to the country by way of consumption in his lifetime.
An unemployed deaf-mute person or laborer will not be as productive or contributing as his/her hearing counterpart.
WHO CAN BENEFIT ?
- Pre-lingual deafness till age 7
- Post-lingual deafness in adults & childrens
- Ski-slope hearing losses - hybrid implants
Age at implantation is almost universally acknowledged now as a major variable in outcome with a CI.
The overwhelming message from research is the younger you implant, the greater the likelihood that the child will achieve the highest levels of auditory performance using his or her cochlear implant. So the ideal time to implant is during this peri-lingual stage in the first 3 years of life, and preferably as early as possible, because although children implanted at the age of 2 years can acquire language at a rate equal to that of normal hearing children, many do not overcome the language gap caused by the absence of language development in the first 2 years of life. For this reason, we specifically state that there is no minimum age for referral to our CI evaluation programme, and in fact encourage the earliest possible referral as this gives the clinic time to undertake pre-operative assessments, and also gives the parents time to make a considered and informed decision, while the child is still in the early critical period for the development of auditory skills and language learning.
As well as the youngest age, it is important to define the upper age limit of implantation in children. This time-line illustrates the cut-off age as 9 years, but children over the age of seven who do regularly use oral/aural communication at home and school, have reasonable speech and language skills and are highly motivated with committed parents may be considered for implantation.
Adults :
- No upper age limit for referral
- They should have restricted or no useful benefit from hearing aids
- If the candidate obtains open set sentence scores in quiet of up to < 40% in the ear to be implanted.
- Candidates with significant speech perception ability must be assessed binaurally and for each ear separately using sentences in quiet, noise and monosyllables.
- Aided audiometric thresholds that fall outside speech range @ 2 kHz & 4kHz
- Realistic expectations of outcomes & commitment to habilitation are discussed at length
The key point: Early intervention!!
Diagnosis at BIRTH should be the aim.
DO NOT wait till the child is too old.
Post meningitis - implantation should be in 2 months.
When not to implant ?
- Hearing Loss of Neural or Central Origin.
- Absence of Cochlear or VIIIth Nerve Development.
- Active Middle Ear Infections.
- Other Contraindications to Surgery.
- Psychological Contraindications.