Iowa Cochlear Implant Clinical Research Center Hybrid L24 and Standard Cochlear Implants in Profoundly Deaf Infants

The purpose of this feasibility study is to evaluate whether a Nucleus L24 and a FDA approved
standard-length device in the contralateral ear can provide useful binaural hearing in
pediatric subjects who have bilateral profound hearing loss, meeting the criteria for
cochlear implantation. Unlike a conventional cochlear implant, the Nucleus L24 is designed to
preserve the regions of the cochlear partition that are apical to the electrode, thus leaving
them available for possible future advances in the field of otolaryngology and hearing
devices, such as mammalian hair cell regeneration techniques or improved implantable hearing
devices. The Nucleus L24 (16 mm) array stimulates the basal turn of the cochlea, in an
attempt to preserve the middle and apical regions of the scala media.

The study will be conducted as a repeated-measure, single-subject experiment. A
single-subject research design (in which each participant serves as his or her own control)
is appropriate because it accommodates the heterogeneity that characterizes hearing-impaired
populations. Blinding or masking procedures are not included in the design, as it is not
possible to conceal the presence or absence of a cochlear implant from device recipients
and/or clinical investigators.

Preoperatively, candidates will be assessed with their current amplification to evaluate
their appropriateness for entrance into the study. The candidates' audiometric configuration
must meet the above inclusion criteria. That is, the candidate must have a profound
sensorineural hearing loss from 250 to 8000 Hz. Prior to testing, the appropriateness of the
hearing aid fitting will be assessed and adjustments made if necessary. In cases where
amplification has not been used for more than one year, new hearing aids will be fit, worn
for a minimum three-month trial and the participants re-evaluated to confirm continuance with
the study.

Fifteen infants will receive one Nucleus L24 array and a FDA approved standard-length array
on contralateral ears. The investigator will alternate every other subject between the right
and left ears as to which ear gets the Nucleus L24. Postoperatively, the right ear only, left
ear only, and the bilateral listening modes will be compared with repeated testing through
five years of age of the child. These comparisons will help to evaluate the effects of
bilateral stimulation using a shorter electrode cochlear implant to possibly preserve the
scala media, organ of Corti, and supporting cells for future medical interventions and a
standard length implant on the contralateral ear. In addition, the investigator will attempt
to compare speech perception and speech/language measure results with age-matched children
implanted with standard-length bilateral devices.

Inclusion Criteria:

1. Twelve to twenty-four months of age at the time of implantation.

2. Audiometric thresholds for frequencies 250 to 8000 Hz in the profound hearing range
bilaterally. The type of hearing loss must be categorized as sensorineural in nature.

3. English spoken as a primary language (mono-lingual English speaking family, where
English is the primary language).

4. Willingness to comply with all study requirements.

5. Minimum of three-month hearing aid trial with appropriately fit hearing aids.

6. Patent cochlea and normal cochlear anatomy as shown by a CT scan. It is standard
clinical practice to perform a CT scan on any patient pursuing cochlear implantation.

Exclusion Criteria:

1. Medical or psychological conditions that contraindicate undergoing surgery.

2. Ossification or any other cochlear anomaly that might prevent complete insertion of
the electrode array.

3. Developmental disabilities or other conditions that would prevent or restrict
participation in the audiological evaluations and clinical trial.

4. Hearing loss of neural or central origin.

5. Unrealistic expectations on the part of the candidate and/or candidate's family,
regarding the possible benefits, risks, and limitations that are inherent to the
surgical procedure(s) and prosthetic devices.

6. Unwillingness or inability of the candidate to comply with all investigational
requirements.

7. Active middle ear infection.