ABSTRACT
Although the cochlear implant has been widely acknowledged as the most successful neural prosthesis, only a fraction of hearing-impaired people who can potentially benefit from a cochlear implant have actually received one due to its limited awareness, accessibility, and affordability. To help overcome these limitations, a 26-electrode cochlear implant has been developed to receive China's Food and Drug Administration (CFDA) approval in 2011 and Conformité Européenne (CE) Marking in 2012. The present article describes design philosophy, system specification, and technical verification of the Nurotron device, which includes advanced digital signal processing and 4 current sources with multiple amplitude resolutions that not only are compatible with perceptual capability but also allow interleaved or simultaneous stimulation. The article also presents 3-year longitudinal evaluation data from 60 human subjects who have received the Nurotron device. The objective measures show that electrode impedance decreased within the first month of device use, but was stable until a slight increase at the end of two years. The subjective loudness measures show that electric stimulation threshold was stable while the maximal comfort level increased over the 3 years. Mandarin sentence recognition increased from the pre-surgical 0%-correct score to a plateau of about 80% correct with 6-month use of the device. Both indirect and direct comparisons indicate indistinguishable performance differences between the Nurotron system and other commercially available devices. The present 26-electrode cochlear implant has already helped to lower the price of cochlear implantation in China and will likely contribute to increased cochlear implant access and success in the rest of the world. This article is part of a Special Issue entitled
Subject(s)
Auditory Perception , Cochlear Implantation/instrumentation , Cochlear Implants , Persons With Hearing Impairments/rehabilitation , Acoustic Stimulation , Acoustics , Adolescent , Adult , Audiometry, Speech , Auditory Pathways/physiopathology , Auditory Threshold , Child , China , Electric Stimulation , Female , Humans , Loudness Perception , Male , Materials Testing , Middle Aged , Persons With Hearing Impairments/psychology , Prosthesis Design , Recovery of Function , Signal Processing, Computer-Assisted , Sound Spectrography , Speech Perception , Young AdultABSTRACT
An integrated vestibular-cochlear implant can be rapidly prototyped and clinically tested by modifying an existing modern cochlear implant. The modifications include addition of gyroscope sensors and reallocation of several electrodes that are normally used for auditory nerve stimulation to the semicircular canals, while sharing the external DSP processor and the internal receiver/stimulator. This paper discusses the validation issues related to hardware and software design that arise in integrating electric hearing and balance onto a single device. The device's initially targeted population will be deaf individuals who also have vestibular impairment since there is a strong ethical justification for vestibular implantation along with minimal additional surgical risk. Because of widespread usage of ototoxic drugs and unique genetic mutations, the patient population with both impaired hearing and balance function is especially prevalent in Asian countries such as China and India. Should such an integrated vestibular-cochlear implant be verified, it could be used to restore balance or treat a wide array of vestibular disorders.