What is the most appropriate option for hearing rehabilitation in a patient with complete deafness on one side and a normal functioning cochlea (Cochlear (auditory portion of the inner ear)) on the opposite side?

BAHA (Bone-Anchored Hearing Aid) is the Most Appropriate Option

For a patient with complete unilateral deafness and a normal functioning contralateral cochlea, BAHA is the most appropriate hearing rehabilitation option. This device transmits sound from the deaf side through bone conduction to the functioning cochlea on the opposite side, effectively addressing the head shadow effect without requiring amplification on the normal-hearing ear 1.

Why BAHA is Optimal for Single-Sided Deafness

Primary Indication

• BAHA is specifically designed for single-sided deafness (SSD) where one ear has profound hearing loss and the contralateral ear has normal hearing 1.
• The device uses a titanium implant in the mastoid bone behind the deaf ear to transmit sound via bone conduction to the functioning cochlea on the opposite side 2, 3.
• This approach eliminates the head shadow effect, allowing the patient to detect sounds originating from the deaf side 2, 4.

Evidence of Benefit

• BAHA improves speech perception in noise when speech is presented frontally with noise on the deaf side, with statistically significant improvements in signal-to-noise ratios (p = 0.001) 2.
• Patient-reported outcomes using the Abbreviated Profile of Hearing Aid Benefit (APHAB) demonstrate clear subjective benefit, with over 90% of patients reporting satisfaction 2, 3.
• Quality of life improvements are documented with hearing-specific instruments, though generic QOL measures show less consistent changes 5, 4.

Why Other Options Are Inappropriate

Cochlear Implant (Option A) - Incorrect

• Cochlear implants are indicated for severe to profound bilateral sensorineural hearing loss with limited benefit from conventional hearing aids 1, 6.
• This patient has a normal functioning cochlea on one side, making cochlear implantation unnecessary and inappropriate 6.
• The "60/60" guideline (60 dB presentation with ≤60% word recognition) for cochlear implant candidacy does not apply when one ear has normal hearing 6.

Conventional Hearing Aid (Option C) - Incorrect

• A conventional hearing aid amplifies sound but provides no benefit when the cochlea is completely non-functional 1.
• The patient has complete deafness on one side, meaning there is no residual hearing to amplify 1.
• Hearing aids require functional cochlear hair cells to transduce amplified sound, which are absent in complete deafness 1.

Middle Ear Implant (Option D) - Incorrect

• Middle ear implants are designed for conductive or mixed hearing loss where the cochlea retains function 1.
• This patient has complete sensorineural deafness on one side, making middle ear implantation ineffective 1.

Auditory Brainstem Implant/ABI (Option E) - Incorrect

• ABIs are reserved for patients with bilateral profound deafness who lack functional cochlear nerves or have had bilateral cochlear nerve damage 6.
• This patient has a normal functioning cochlea on the opposite side, making ABI unnecessary and overly invasive 1.

Important Clinical Considerations

BAHA Limitations to Counsel Patients About

• Sound localization does not improve with BAHA, as lateralization scores remain at chance levels (50%) even after implantation 2, 4.
• When noise is presented frontally with speech on the deaf side, BAHA may actually worsen the signal-to-noise ratio (p = 0.003) compared to the unaided condition 2.
• The device requires surgical implantation with potential complications including skin reactions (minor in most cases) and implant loss rates of 6.1-19.4% 5, 3.

Surgical Considerations

• Implantation can be performed as an outpatient procedure under local anesthesia in adults 3.
• The titanium fixture requires osseointegration before the external processor can be attached 3.
• Long-term complication rates are low, with transient skin reactions or local infections occurring occasionally 3.

Alternative Non-Surgical Option

• CROS (Contralateral Routing of Signal) hearing aids represent a non-surgical alternative that uses a microphone on the deaf ear transmitting to a speaker on the normal-hearing ear 1.
• However, BAHA CROS demonstrates superior patient satisfaction compared to conventional CROS devices, particularly in lifting the head shadow effect 2.