1.07 CME

Cochlear Implants: Case Selection and Surgical Approach

Speaker: Dr. Sanjay Helale

Head of ENT Department and Cochlear Implant Programme at Criticare Asia Multispeciality Hospital and Research Centre, Kurla (W), Mumbai and Honorary Consultant at Kurla Bhabha Municipal Hospital, Mumbai

Description

This webinar will provide a comprehensive overview of patient selection criteria for cochlear implantation, including audiological, radiological, and clinical evaluation. It will discuss indications in both pediatric and adult populations, along with contraindications and preoperative counseling considerations. The session will outline key surgical approaches, anatomical landmarks, and techniques to optimize electrode placement and hearing outcomes. Common intraoperative challenges and strategies to prevent complications will also be highlighted. Participants will gain practical insights into achieving safe surgery and improved auditory rehabilitation outcomes.

Summary

The natural mechanism of hearing involves three parts: the outer, middle, and inner ear. The inner ear contains the cochlea, the target for cochlear implants, which replace non-functioning cochleas. Hearing loss can be conductive (outer or middle ear), sensorineural (inner ear), or mixed (outer, middle, and inner ear). A normal audiogram range is within 20 decibels; 20-40 is mild loss, 40-60 moderate, and above 80 severe. Cochlear implants are indicated for severe to profound hearing loss.
Hearing loss, although a common birth defect, is reversible. It can lead to dementia, increased risk of danger due to the loss of protective hearing mechanisms, depression, dependence, disturbed daily life, deprivation of pleasure, and social isolation. Hearing loss impacts mental health by hindering conversation, reducing social engagement, and affecting cognition due to poor brain input and increased cognitive load, resulting in "hearing fatigue." Solutions include hearing aids or, when they are insufficient, cochlear implants.
Cochlear implants are electronic devices that convert sound into electrical signals, stimulating the auditory nerve directly. Pre-lingual deafness refers to hearing loss before speech acquisition, while post-lingual deafness occurs after speech and language development. Early detection and intervention are crucial because of a critical period where the auditory cortex is receptive to stimulation. Without auditory input, the auditory cortex is taken over by the visual cortex.
The "rule of 1-3-6" dictates that every newborn should be assessed for hearing within one month, diagnosed within three months, and intervened before six months. Studies have shown that children intervened early perform closer to normal individuals. Sensory integration systems are interconnected, and the experiences within the first years of life affect the physical architecture of the developing brain.
Assessment protocols for newborns include OAE (Otoacoustic Emissions), AABR (Automated Auditory Brainstem Response), and AOA. Suspected hearing-impaired children undergo ENT examination, audiological evaluation, and hearing aid trials. Vaccination and nutrition are also addressed before surgery. The cochlear implant surgery is followed by audiological therapy to monitor the child's progress, with the goal of mainstreaming the child into a normal school environment.
Hearing aids amplify sound to the tympanic membrane, relying on a functioning cochlea. Cochlear implants bypass a non-functioning cochlea, delivering sound directly to the auditory nerve. A cochlear implant consists of an internal component surgically placed under the skin with electrodes in the cochlea, and an external sound processor attached via magnet.
The ideal age for cochlear implantation in pre-lingual deafness is as early as possible. Selection involves audiological, radiological, speech-language assessments, and counseling. The process includes candidacy evaluation, surgery and recovery, switch-on, and auditory training. Modern surgery involves smaller incisions, similar to tympanoplasty mastoidectomy procedures. Cochlear implants are generally reliable for life.
Cochlear implant programs are teamwork oriented involving pediatric experts, anesthesiologists, ENT surgeons, pediatricians, clinical psychologists, radiologists, audiologists, and audioperable therapists. Audioperable therapy is crucial, accounting for 70-80% of the success, as it helps the child comprehend and interpret the sounds they now hear.
Bilateral cochlear implantation is often recommended. There are situations where cochlear implantation is not appropriate and instead a Bone Anchored Hearing Aid (BAHA) is used. In cases of ossified cochleas, partial or complete insertion is attempted depending on the extent of ossification. Hearing preservation is a goal of the surgery utilizing delicate techniques, intraoperative steroids, and careful round window approach.