Investigating the benefits from cochlear implantation in patients with single-side deafness

Chief investigator

Professor Gerry O'Donoghue

Study team

Dr Pádraig Kitterick
Associate Professor Douglas Hartley
Dr-Ing Bernhard Seeber

Kevin Green (Central Manchester University Hospitals NHS Foundation Trust)
Dan Jiang (Guys and St Thomas’s NHS Foundation Trust, London)
Professor Shakeel Saeed (UCL Ear Institute, London)
Dr Huw Cooper (University Hospitals Birmingham NHS Foundation Trust)


Cochlear Europe Ltd (part funding)

Study period


Individuals with severe or profound hearing loss in one ear experience great difficulty in understanding speech in background noise and in localising sounds. Standard care is a specialised hearing aid called a ‘contralateral routing of signals’ (CROS) system, which picks up sound at the deaf ear and delivers it to the opposite ear. This enables the user to hear sounds at the poor side, but does not allow spatial separation of sound sources because all sounds are perceived in one ear. Consequently, benefits are limited and so sustained use of CROS systems is low.

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There have been some recent reports from outside the UK of successful cochlear implant use in patients with single-side deafness, where a cochlear implant can restore some hearing in the deaf ear. This study therefore measures outcomes from a cohort of 10 patients who will first receive a CROS system, the current standard of care on the NHS, and will subsequently receive a cochlear implant. The study will compare outcomes using a CROS system to outcomes using the cochlear implant. This is a multi-centre trial involving five UK cochlear implant centres with the research infrastructure being provided by NIHR Nottingham Hearing BRU and Medical Research Council Institute of Hearing Research (MRC IHR).