4Cochlear Implant for Single-Sided Deafness with Tinnitus

FWhy the silent ear screams

Single-sided deafness (SSD) describes a profound sensorineural loss in one ear with a normal or near-normal opposite ear. Many of these patients are not troubled most by the loss of stereo hearing — they are troubled by a relentless tinnitus in the dead ear. The deafferentation model explains why: when the cochlea stops feeding the brain, central auditory neurons turn up their gain to compensate, and that amplified spontaneous activity is perceived as phantom sound [2013].

This gives SSD a special logic for treatment. Unlike most subjective tinnitus, the generator here is anatomically localised to one cochlea and one auditory nerve. If you could restore meaningful input to that ear, the deafferentation that drives the tinnitus might reverse. A cochlear implant does exactly that — it bypasses the dead hair cells and stimulates the surviving auditory nerve directly.

TThe pivotal evidence

The idea that an implant could treat tinnitus — rather than merely accompany hearing restoration — was crystallised by Van de Heyning and colleagues in Antwerp. In their landmark series, patients with incapacitating unilateral tinnitus and ipsilateral SSD were implanted primarily to control the tinnitus, and tinnitus loudness fell dramatically when the device was switched on, returning when it was switched off [2008]. That on/off reproducibility was powerful evidence that the electrical input itself was doing the work.

Subsequent reviews consolidated the signal. Arts and colleagues synthesised the early literature and concluded that cochlear implantation produced consistent, clinically meaningful tinnitus reduction in SSD, positioning it as a genuine therapeutic option rather than an incidental benefit [2012]. Independent groups reproduced the effect: Holder and colleagues reported reliable tinnitus suppression alongside the expected gains in localisation and speech-in-noise [2017].

Crucially, the benefit endures. Long-term follow-up of the original cohorts — now extending beyond two decades — shows that tinnitus relief and hearing benefit are largely maintained, with sustained device use being the key to keeping the tinnitus suppressed [2026].

THow much relief, and how reliable

Across SSD series, most implanted patients report substantial tinnitus reduction and a meaningful drop in Tinnitus Handicap Inventory (THI) scores; a sizeable minority achieve near-complete suppression while the device is worn. The effect is partly a direct electrical phenomenon and partly the result of reversing maladaptive central gain over weeks to months [2008].

Two practical caveats matter. First, suppression is generally device-dependent — switch the processor off and the tinnitus tends to creep back, which is why daily wear-time is counselled as essential [2026]. Second, response is not universal: a small group sees little change, and a rare patient reports new or altered tinnitus. Honest preoperative counselling about this spread of outcomes protects both patient and clinician [2012].

CCandidacy and where it sits among the alternatives

The ideal candidate has profound SSD, a present and stimulable cochlear nerve, intractable ipsilateral tinnitus that has failed sound therapy and counselling, and realistic expectations. A patent, non-ossified cochlea and a confirmed nerve on imaging are prerequisites — without a nerve to stimulate, the implant cannot work, which is the subject of the next module.

Among SSD options, the implant is unique in addressing the tinnitus. Contralateral routing of signal (CROS) devices and bone-conduction systems reroute sound to the good ear but leave the deaf cochlea silent — they improve audibility on the bad side without treating the phantom sound. For the SSD patient whose dominant complaint is tinnitus, only the cochlear implant restores true input to the affected ear [2017].

Indications have expanded accordingly. Regulators and guideline bodies increasingly recognise SSD — with disabling tinnitus as a strong supporting factor — as a formal implant indication, moving this from experimental to mainstream in well-selected patients [2014].