Cochlear Implants, Normal Hearing, and Single-Sided Deafness
Many reports in the literature have demonstrated that cochlear implants are a reasonable, successful, and viable option for people with severe-to-profound unilateral hearing loss (Arndt et al 2011; Baguley, 2010; Buechner et al 2010; Popelka et al 2010; Van Zon et al 2015; Van De Heyning et al 2008).
Kitterick et al (2014) note that single-sided deafness (SSD) occurs in approximately 20 people per 100,000. People with SSD have “little or no ability” to localize sound and they have a poor ability to understand speech in noise due to a lack of access to interaural timing and loudness differences (ITDs and ILDs). They note that “the indiscriminate routing of signals to a single ear can have detrimental effects when interfering sounds are located on the side of the impaired ear….” CROS hearing aids are not designed to restore access to ITDs and ILDs and patients are often dissatisfied with wearing a device on the non-impaired ear. Additionally, they report bone-anchored hearing devices (BAHDs) do not restore binaural hearing for people with severe-to-profound SSD.
Kitterick et al and associates report that the “standard of care” (in the UK’s NHS system) for people with SSD has been the contralateral routing of signals (CROS) hearing aid. Recent published evidence has suggested that cochlear implantation in individuals with a SSD can restore access to the binaural cues that underpin the ability to localize sounds and segregate speech from other interfering sounds….” As such, Kitterick et al have proposed a multi-center within subjects and a longitudinal trial to “provide evidence for the efficacy of cochlear implantation compared to the contralateral routing of signals (CROS). Among the primary outcomes measures to be acquired include evaluation of sound localization, testing of speech understanding in noise, obtaining earing-specific quality of life measures through the Speech, Spatial and Qualities of Hearing Scale (SSQ), the Glasgow Hearing Aid Benefit Profile (GHABP), the Glasgow Benefit Inventory (GBI), and the Tinnitus Functional Index (TFI), a user diary, and more. Details can be accessed here.
For More Information, References, and Recommendations
Arndt S, Aschendorff A, Laszig R, Beck R, Schild C, Kroeger S, Ihorst G, Wesarg T. (2011) Comparison of Pseudo-binaural Hearing to Real Binaural Hearing Rehabilitation After Cochlear Implantation in Patients With Unilateral Deafness and Tinnitus. Otology & Neurotology 32(1):39-47.
Baguley DM. (2010: Cochlear Implants in Single-Sided Deafness and Tinnitus. Seminars in Hearing 31(4):410-413.
Buechner A, Brendel M, Lesinki-schiedat A, Wenzel G, Frohne-Buechner C, Jaeger B, Lenarz, T. (2010) Cochlear Implantation in Unilateral Deaf Subjects Associated With Ipsilateral Tinnitus. Otology & Neurotology 31(9):1381-1385.
Hayes D. (2006) A Practice Guide to CROS and BiCros. Audiology Online June 24.
Kitterick PT, O’Donoghue GM, Edmondson-Jones M, Marshall A, Jeffs E, Craddock L, Riley A, Green K, O’Driscoll M, Jiang D, Nunn T, Saeed S, Alesky W, Seeber BU. (2014) Comparison of the Benefits of Cochlear Implantation versus Contralateral Routing of Signal Hearing Aids in Adult Patients with Single-Sided Deafness—Study Protocol for a Prospective Within-Subject Longitudinal Trial. BMC Ear Nose Throat Disord 14:7.
Oeding K, Valente M. (2013) Sentence Recognition in Noise and Perceived Benefit of Noise Reduction on the Receiver and Transmitter Sides of a BiCROS Hearing Aid. Journal of the American Academy of Audiology 24:980-991.
Popelka GR, Derebery J, Blevins NH, Murray M, Moore BCJ, Sweetow RW, Wu B, Katsis M. (2010) Preliminary Evaluation of a Novel Bone-Conduction Device for Single-Sided Deafness. Otology & Neurotology 31:492-497.
Tavora-Vieira D, Marino R, Acharya A, Rajan GP. (2015): The Impact of Cochlear Implantation on Speech Understanding, Subjective Hearing Performance, and Tinnitus Perception in Patients with Unilateral Severe to Profound Hearing Loss. Otology & Neurotology 36:430-436.
Van Zon A, Peters JPM, Stegeman I, Smit AL, Grolman W. (2015) Cochlear Implantation for Patients with Single-Sided Deafness or Asymmetrical Hearing Loss--A Systematic Review of the Evidence. Otology & Neurotology 36:209-219.
Van De Heyning P, Vermeire K, Diebl M. (2008) Incapacitating Unilateral Tinnitus in Single Sided Deafness Treated by Cochlear Implantation. Ann Otol Rhinol 117:645-652.