Absolute indication for Cochlear implantation is:
Correct Answer: Auditory nerve
Description: Ans. d. Auditory nerve Cochlear Implants are used in cochlear type of sensorineural hearing loss where nerve fibers remain intact and functional Cochlea and auditory nerve should be presentdeg in the patients of sensorineural hearing loss planned for cochlear Implants Cochlear Implants Electronic devices which conve sound signal to electrical impulses which directly stimulate the fibers of CN VIII Cochlear implants replace the nonfunctional transducer system of hair cells of cochlea. Used in cochlear type of sensorineural hearing loss where nerve fibers remain intact and fenctional Electrode array consists of multiple electrodes and is implanted in the scala tympani of the cochlea. It stimulates the fibers of CN VIII. Cochlear Implants Selection criteria for Adults Age: 18 years or more Bilateral severe to profound hearing loss Limited or no benefit from hearing aids No medical contraindicationdeg to undergo surgery Cochlea and auditory nerve should be present Realistic expectation Good family and social suppo Adequate cognitive function to be able to use the disease Post lingually deafened adults are good candidates. Results are not so good in pre-lingually deaf adults unless they had been receiving aural-oral training for communication. Selection criteria for children Bilateral profound or severe to profound hearing loss Minimal or no benefit from hearing aid No medical contraindication Cochlea and auditory nerve should be present Good family and social suppo Adequate cognitive function to be able to use the disease Auditory deprivation in the early developmental period causes degenerative changes in central auditory pathway. Now implants can be used at an age as early age 12 months Implants can be used in both pre-lingually and post-lingually deafened infants and children Hearing Aids Contralateral routing of signals (CROS) In this type, microphone is fitted on the side of the deaf ear and the sound picked up is passed to the receiver placed in the better ear. Useful for the person with one ear severely impaired and helps in sound localization coming from the side of deaf ear Auditory Brainstem Implant (ABI) This implant is designed to stimulate the cochlear nuclear complex in the brainstem directly by placing the implant in the lateral recess of fouh ventricle Such implants are needed when CN VIII has been severed in surgery of vestibular schwannomadeg. In these cases, cochlear implants are of no use. In unilateral acoustic neuroma, ABI is not necessary as hearing is possible from the contralateral side but in bilateral acoustic neuromas as NF2, rehabilitation is required by ABI
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