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In this article, Alhabib et al consider the changes to electrode impedance with early device activation (day one) compared to conventional activation (day 30). Activation at day 30 is a cautious approach, which has been popular for many years. However, the safety of early activation has been shown, and there are obvious advantages; not least, in a population with congenital hearing loss, activation a month earlier may have a measurable long-term impact on outcome. This article looks at the effects on impedance. The article has the obvious weakness that the two groups are not randomised, and clearly selected patients have been offered early activation. This means we have to be slightly cautious about interpretation of the data, however reading the article, it becomes clear that the primary indication for early activation was for those patients who travel great distances for care. The sample of 40 ears in each group is adequate. The effects of electrical stimulation through the implant on soft tissues in the inner ear are incompletely understood and this makes it difficult to know whether early activation will promote or indeed prevent intra-cochlear fibrosis. Certainly, however, that the impedances - which are an imperfect but easily recorded marker of such a process - in the long term are unchanged, is reassuring. Clearly to the patient, however, impedance is immaterial - rather aided speech perception, preservation of residual hearing, aided audiometry, quality of life outcomes, speech intelligibility etc… are the salient measures. But to the surgeon, studies like this provide some reassurance. 

Effect of early activation of cochlear implant on electrode impedance in pediatric population.
Alhabib SF, Abdelsamad Y, Yousef M, et al.
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Robert Nash

BM BCh, MA(Oxon), MRCS, MA, DOHNS, FRCS (ORL-HNS), Great Ormond Street Hospital, London, UK.

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