Published in May 2008, Outcomes in bilateral cochlear implantation is the first study to demonstrate a favourable cost utility following bilateral implantation.

There is an ever-increasing body of research growing that support the case for bilateral cochlear implantation.

The majority of the studies aim to quantify the measurable benefits of binaural hearing as experienced by users of bilateral cochlear implants. As explained in the benefits of binaural hearing, these are:

1. localisation
2. hearing in noise
3. the head shadow effect

Some of theses studies also describe the qualitative improvements in user’s lives, the importance of which cannot be over-estimated in terms of mental health and general well-being.

Abstracts from all published, peer-reviewed life science papers can be found at PubMed. A search on ‘bilateral cochlear implant’ will return hundreds of papers – a number that is increasing month by month.

Note: it is rarely possible to read the actual papers themselves without subscribing to the journal itself and some level of payment.

Some recently published studies with children as the subjects include:

• Hearing benefits of second-side cochlear implantation in two groups of children (October 2007)
• The benefits of sequential bilateral cochlear implantation for hearing-impaired children. (August 2007)
• Sound localization ability of young children with bilateral cochlear implants. (June 2007)
• Bilateral cochlear implants in children: localization acuity measured with minimum audible angle (2006)
• Importance of age and post-implantation experience on speech performance in children with sequential bilateral cochlear implants (June 2006)

O’Donoghue and Murphy have recently published Bilateral cochlear implantation: an evidence-based medicine evaluation which looks at all the evidence available at the time of writing and comes to the following conclusion:

The available evidence indicates that bilateral cochlear implantation confers material benefits not achievable with unilateral implantation, specifically in terms of sound localization and speech understanding in noise. [Well-designed prospective studies of sufficient size are now needed to precisely quantify these benefits, to validate outcome measures especially in children and to define the criteria for intervention.]

This review, by respected U.S surgeon B. Robert Peters, provides an excellent summary of the issues surrounding unilateral hearing loss and the benefits of binaural hearing. It is important to note, when arguing for bilateral implantation, that there is evidence relating to the impact of unilateral hearing loss on a child’s outcomes (educationally and in terms of mental health) that has direct bearing.
Rationale for Bilateral cochlear Implantation

The work of F.H Bess is referred to very frequently as a defining study relating to speech recognition in adverse (noisy) conditions while JE Lieu’s paper of 2004 outlines the impact on education of unilateral hearing loss and the importance of providing binaural hearing.
Speech-language and educational consequences of unilateral hearing loss in children

This is further explored in Unilateral Hearing Loss in Children (English and Church)

Many major medical insurers in the United States of America regard unilateral and bilateral implants as ‘a medically necessary prosthetic’ for children and adults.

• Aetna’s Policy Bulletin (October 2007)
• Anthem Blue Cross Blue Shield Medical Policy (July 2007)
• FCHP