What are the indications, eligibility criteria, and pre‑operative evaluation for cochlear implantation in patients with severe to profound sensorineural hearing loss?

Cochlear Implantation: Indications, Eligibility, and Pre-operative Evaluation

Primary Recommendation

Refer patients for cochlear implantation evaluation when they have severe to profound sensorineural hearing loss with appropriately fitted hearing aids yet demonstrate ≤60% word recognition at 60 dB presentation (the "60/60" guideline), which has 96% sensitivity for identifying appropriate candidates. 1, 2

Eligibility Criteria

Audiometric Requirements

The "60/60" guideline serves as the primary candidacy criterion:

• Aided word recognition score ≤60% at 60 dB presentation in the ear to be implanted 1, 2
• For asymmetric hearing loss: unaided pure-tone average ≥70 dB HL in the affected ear 1, 2
• For bilateral sensorineural hearing loss: documented >40 dB loss with limited speech perception benefit (best aided word/sentence cognition ≤60% at 60 dB) 1

Documentation of Hearing Aid Trial

Patients must demonstrate limited benefit from appropriately fitted conventional amplification:

• Documentation of appropriate hearing aid fitting with real-ear measurements is required 1
• The hearing aid trial confirms that conventional amplification has clearly failed before proceeding 2
• However, do not delay cochlear implantation with prolonged hearing aid trials when patients clearly meet the 60/60 criteria 2

Pre-operative Evaluation

Required Imaging Studies

Confirm intact cochlear nerves and assess cochlear anatomy:

• CT or MRI must document intact cochlear nerves for cochlear implant placement 1
• Imaging identifies any anatomical abnormalities that may affect surgical planning 1

Functional Assessment

Evaluate communication goals and quality of life impact:

• Assess if current amplification meets communication goals 3
• Document hearing-related quality of life deficits 3
• Evaluate the degree of hearing difficulty with poor speech understanding despite amplification 3

Special Populations

Pediatric Candidates

Age-specific criteria apply for children:

• Infants with profound bilateral hearing loss: eligible at 12 months of age 2
• Children with bilateral severe hearing loss: eligible at 24 months of age 2
• Developmental conditions (developmental delay, autism) should not preclude consideration 2
• The American Academy of Pediatrics recommends careful consideration for any child receiving limited benefit from appropriately fitted hearing aids 4

Unilateral Hearing Loss

Consider implantation when the difference between ears is significant:

• For unilateral severe to profound hearing loss with normal contralateral ear, implantation can be considered when the difference exceeds 15 dB 4
• Benefits include improved sound localization and hearing in noisy environments 4

Expected Outcomes

Cochlear implantation provides substantial functional improvements:

• Significant improvements in sound localization and speech discrimination 2
• 96% of patients with preoperative tinnitus report improvement following implantation 1, 2
• Significant improvement in patient-reported quality of life measures for hearing rehabilitation 2
• Restoration of substantial hearing levels critical for safety and social participation 1

Critical Pitfalls to Avoid

Do not delay referral when criteria are met:

• There is significant under-referral of patients who would benefit from cochlear implantation 3
• Do not continue hearing aid trials when conventional amplification has clearly failed and patients meet the 60/60 criteria 2
• Do not avoid implantation due to dry tympanic membrane perforation, as this is manageable surgically 1, 2

Do not select inappropriate alternative devices:

• BAHA is contraindicated in bilateral profound hearing loss, as it requires a better-hearing ear 1, 2
• CROS aids are designed for single-sided deafness with normal contralateral ear, not bilateral profound hearing loss 1, 2
• Conventional hearing aids are ineffective in complete deafness as they require functional cochlear hair cells 2

Ear Selection for Implantation

Select the ear with worse hearing:

• Implant the ear with poorer audiometric function 2
• Stable dry perforations do not contraindicate cochlear implantation 1, 2
• The presence of severe tinnitus in one ear supports selecting that ear given the 96% improvement rate 2

Follow-up Requirements

Establish systematic monitoring:

• Assess hearing at least every 3 years in patients with known hearing loss 3
• Assess if communication goals have been met within 1 year or at subsequent encounters 3
• Ongoing audiological assessment with electroacoustic and real-ear checks of the device is necessary post-implantation 2