Long-Term Evolution of the Electrical Stimulation Levels for Cochlear Implant Patients

ENT Service, San Cecilio University Hospital, Granada, Spain.
Clinical and Experimental Otorhinolaryngology (Impact Factor: 0.85). 12/2012; 5(4):194-200. DOI: 10.3342/ceo.2012.5.4.194
Source: PubMed


The stimulation levels programmed in cochlear implant systems are affected by an evolution since the first switch-on of the processor. This study was designed to evaluate the changes in stimulation levels over time and the relationship between post-implantation physiological changes and with the hearing experience provided by the continuous use of the cochlear implant.
Sixty-two patients, ranging in age from 4 to 68 years at the moment of implantation participated in this study. All subjects were implanted with the 12 channels COMBI 40+ cochlear implant at San Cecilio University Hospital, Granada, Spain. Hearing loss etiology and progression characteristics varied across subjects.
The analyzed programming maps show that the stimulation levels suffer a fast evolution during the first weeks after the first switch-on of the processor. Then, the evolution becomes slower and the programming parameters tend to be stable at about 6 months after the first switch-on. The evolution of the stimulation levels implies an increment of the electrical dynamic range, which is increased from 15.4 to 20.7 dB and improves the intensity resolution. A significant increment of the sensitivity to acoustic stimuli is also observed. For some patients, we have also observed transitory changes in the electrode impedances associated to secretory otitis media, which cause important changes in the programming maps.
We have studied the long-term evolution of the stimulation levels in cochlear implant patients. Our results show the importance of systematic measurements of the electrode impedances before the revision of the programming map. This report also highlights that the evolution of the programming maps is an important factor to be considered in order to determine an adequate calendar fitting of the cochlear implant processor.

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    • "This is particularly likely with young children, who are often unable to accurately report on the quality of the auditory percept. It is also important to note that changes in auditory percept may alternatively be the result of intracochlear (or even central) physiological changes, without any change in the characteristics of the electrical stimulation through device malfunction [37] [41]. Because of the many uncertainties around ICS and electrode malfunction, CI manufacturers have developed ways of testing the various components of their devices in situ, most of which currently involve retrieving data on component function from the ICS through " back-telemetry " . "
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    • "Three centers have less than 1 annual session (Hannover and London-RNTNE every second year, Nijmegen every third year, and Mumbai on patient's request). It seems that these annual sessions are merely planned for verification and to reassure that the performance has not deteriorated, rather than for modifying the MAPs which remain rather stable after the initial months [15]. From that perspective it seems justified to increase the interval of one year. "
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