What are the indications and contraindications for cochlear implantation in patients with bilateral severe to profound sensorineural hearing loss (pure‑tone average ≥70 dB hearing level) who obtain limited benefit from appropriately fitted hearing aids?

Cochlear Implantation Indications

Cochlear implantation is indicated for patients with bilateral severe to profound sensorineural hearing loss (pure-tone average ≥70 dB HL) who demonstrate aided word recognition scores ≤60% at 60 dB presentation despite appropriately fitted hearing aids with real-ear measurements. 1

Primary Candidacy Criteria

The American Academy of Otolaryngology-Head and Neck Surgery establishes the "60/60" guideline as the gold standard for identifying cochlear implant candidates, which demonstrates 96% sensitivity 1. This requires:

• Audiometric threshold: Pure-tone average ≥70 dB HL in the affected ear(s) 1, 2
• Speech perception failure: Best aided word or sentence cognition ≤60% at 60 dB presentation 1
• Limited benefit from amplification: Documentation showing >40 dB loss with limited speech perception benefit from appropriately fitted hearing aids 1

Pre-Implantation Requirements

Before proceeding with cochlear implantation, the following must be documented:

• Imaging confirmation: MRI or CT demonstrating intact cochlear nerves bilaterally 1, 2
• Appropriate hearing aid trial: Documentation of proper hearing aid fitting with real-ear measurements 1
• Audiometric testing: Comprehensive evaluation including pure-tone audiometry confirming sensorineural etiology 2

Critical Pitfall to Avoid

Do not delay cochlear implantation in favor of continued hearing aid trials when conventional amplification has clearly failed, as patients with bilateral profound hearing loss and no benefit from hearing aids are definitive candidates for cochlear implantation. 1

Pediatric-Specific Indications

For children, cochlear implantation should be carefully considered for any child receiving limited benefit from appropriately fitted hearing aids 3, 4. The FDA guidelines specify:

• Profound bilateral hearing loss: Eligible at 12 months of age 3
• Severe bilateral hearing loss: Eligible at 24 months of age 3
• Developmental conditions: The presence of developmental delay or autism should not preclude consideration of cochlear implantation 3

While guidelines typically recommend a hearing aid trial before implantation, exceptions exist when audiometric data clearly indicates profound loss that would not benefit significantly from amplification 4. Delaying intervention can impact speech and language development during critical periods for language acquisition 4.

Special Populations

Unilateral Hearing Loss

For unilateral severe to profound hearing loss with normal hearing in the contralateral ear, cochlear implantation can be considered when the difference between ears is significant (>15 dB) 4. Infants and young children with unilateral hearing loss should be assessed for appropriateness of hearing aid fitting, though depending on the degree of residual hearing, a hearing aid may or may not be indicated 3, 4.

Asymmetric Hearing Loss

Patients with asymmetric hearing loss require unaided pure-tone average ≥70 dB HL in the affected ear 1. Some cases of asymmetric hearing loss with intensive tinnitus in the deaf ear may also qualify 5.

Neural Hearing Loss

Benefits from cochlear implants in children with neural hearing loss have been documented, though outcomes are variable 3. A trial fitting with hearing aids is indicated until usefulness can be determined, with the decision to continue or discontinue based on benefit derived 3.

Expected Outcomes

Patients undergoing cochlear implantation can expect:

• Hearing restoration: Substantial hearing levels enabling speech perception and environmental sound awareness 1, 2
• Tinnitus improvement: 96% likelihood of improvement if tinnitus is present 1, 2
• Functional benefits: Improved sound localization and speech reception in noise, critical for safety and social participation 1, 2, 4

Contraindications

Absolute contraindications include:

• Absent or disrupted cochlear nerve on imaging 1, 6
• Labyrinthine and cochlear aplasia (requires auditory brainstem implantation instead) 6
• Cochlear nerve aplasia (requires auditory brainstem implantation instead) 6

Relative considerations that do NOT contraindicate implantation:

• Dry tympanic membrane perforation (manageable surgically) 1
• Temporal bone fractures (should be reviewed and managed before implantation) 2
• Enlarged vestibular aqueduct (anatomy should be compatible with implant placement per MRI) 4

Post-Implantation Management

Essential components for optimal outcomes include:

• Individualized programming: Frequency mapping tailored to the patient 2
• Auditory rehabilitation: Speech perception training and environmental sound recognition 2
• Regular monitoring: Ongoing audiologic assessments to adjust programming and ensure optimal performance 2
• Pediatric follow-up: Long-term validation of communication, social-emotional, and cognitive development to ensure progress commensurate with abilities 3