[Preoperative auditory evaluation and postoperative follow-up in cochlear implantees : The role of objective...

The primary diagnostic aim prior to cochlear implantation is establishment of a comprehensive and multidisciplinary diagnosis, in order to subsequently begin therapy as early as possible. Audiological evaluation prior to implantation employs a test battery-approach, including subjective and objective procedures. Objective measures show high reliability and therefore play a major role in the diagnosis of difficult-to-test subjects such as infants and young children. During postoperative follow-up, objective measures offer a valid method for analyzing the effects of different stimuli on the auditory system. Particularly in infants, children, and uncooperative patients, the results of these tests enable the speech processor settings to be optimized, the hearing benefit to be assessed, and treatment to be adapted accordingly. Auditory brainstem responses (ABR) offer an excellent test/retest and inter-/intrarater reliability and validity, and are the most commonly used method for objective hearing threshold estimation and evaluation of the functional integrity of the lower auditory pathway. The use of narrow-band stimuli allows frequency-specific threshold estimation; analysis of stationary auditory steady state potentials (ASSR) adds the advantages of automated objective detection. Electrocochleography and electrically evoked ABR give valuable information in special cases. The use of cortical potentials (CAEP) in response to speech stimuli is quite promising, although the high response variability currently limits this method's clinical application. An audiological test-battery approach combining the results of subjective and objective measures leads to significantly increased reliability of preoperative diagnosis and postoperative follow-up in cochlear implantees.