Evaluation of Cochlear Implantation in Unilateral or Asymmetric Hearing Loss in Children.

Today, unilateral hearing loss must be assessed and managed just as bilateral hearing loss is. It is recommended to consider the auditory difficulties caused by the loss of stereophonic hearing and to offer auditory rehabilitation as early as possible. Studies show that hearing devices can be effective in certain cases and for specific auditory modalities. The prognostic factors for successful hearing aid adaptation are linked to early intervention and the presence of residual hearing (using a BiCROS system). However, the cochlear implant remains the only device capable of potentially restoring contralateral auditory function in cases of single-sided deafness (SSD) and severe to profound unilateral hearing loss with asymmetrical deafness

Unilateral congenital deafness has significant repercussions on a child's development. Numerous studies on this population have demonstrated its impact on speech and language development, as well as academic progress. Monaural hearing increases the risk of listening fatigue and causes considerable difficulty in sound localization and speech perception in noisy environments, as these abilities rely on binaural hearing.

Recent research has also indicated that in children with unilateral deafness, the better ear may be affected by sensory deprivation in the impaired ear. Despite these substantial effects, treatment options for these children remain limited. Traditional hearing aids are insufficient to restore functional hearing in cases of profound deafness. The only routinely available options are a Bone-Anchored Hearing Aid (BAHA) or a Contralateral Routing of Sound (CROS) system. While these devices allow the signal from the affected side to be transmitted to the better ear, they do not restore binaural hearing, unlike cochlear implants (CIs).

A growing body of evidence has demonstrated the benefits of cochlear implantation on speech perception in noise and sound localization in adults. However, in France, CIs are currently indicated only for cases of severe to profound unilateral deafness associated with debilitating tinnitus, and only when alternative treatments-such as CROS systems and osseointegrated hearing aids-have failed in children. While studies suggest that children may achieve similar outcomes, no clinical research has been conducted. This study aims to evaluate functional performance and neurological correlates in unilaterally implanted children with unilateral hearing loss, in comparison with their hearing-aided peers

Eligibility Criteria:
Inclusion Criteria:

* Child aged 4 to 6 years at the time of inclusion
* Using spoken French as the primary mode of communication
* Diagnosed with unilateral or asymmetric hearing loss :

Unilateral is defined by severe to profound hearing loss in the affected ear (thresholds \> 70 dB at ≥ 4 frequencies, established by audiometry or ASSR) and normal hearing in the better ear (thresholds ≤ 25 dB between 500-4000 Hz, established by audiometry or ASSR).

Asymmetric is defined by severe to profound hearing loss in the weaker ear (thresholds \> 70 dB at ≥ 4 frequencies, established by audiometry or ASSR) and mild hearing loss in the better ear (thresholds between 30-40 dB at ≤ 4 frequencies, established by audiometry or ASSR).

* Written informed consent from both legal guardians (or the sole guardian, if applicable)
* Affiliated with a health insurance system or entitled to coverage

Exclusion Criteria:

* Severe neurological disorder, identified by MRI and/or a neuro-pediatric assessment
* Severe cognitive, child psychiatric, or developmental delay
* Severe cochleo-vestibular malformation
* Severe cochlear nerve malformation
* Social circumstances preventing long-term follow-up
* Family not proficient in spoken French
* Patient fitted with a CROS or BiCROS system
* Patient with a contraindication to implantation surgery or anesthesia (including lack of meningitis/pneumococcal vaccination)