20 Years of Bilateral Cochlear Implantation - an Analysis of the Implanted Patients

Binaural hearing is essential for localization abilities and improves the speech perception in noise. Since 20 years, bilateral cochlear implantation is routinely performed to restore binaural hearing. In this crosssectional study, we evaluated speech perception in quiet (Freiburger monosyllables, Hochmair-Schulz-Moser (HSM) sentence test, each at 70 dB) and in noise (HSM test, signal-to-noise ratio 10 dB) in 103 out of 165 adult patients who were bilaterally implanted in Wurzburg between 1995 and June 2014. In almost half the patients, the second implanted side showed the better speech perception. Compared to the first implanted side, the average monosyllable scores with bilateral implants were improved from 54 to 63 % and the HSM scores from 86 to 96 %. In noise the speech perception improved from 47 to 65 %. The speech perception of the second implanted side was independent of the time interval between the implantation of both sides in this cohort of postlingually deafened patients. This cross-sectional data underline the importance of bilateral cochlear implantation for speech understanding in quiet and even more in noise and thus, for the everyday life. For this, bilateral cochlear implantation should be the generally accepted standard in the treatment of deaf patients.