Evaluation of the electrically evoked action potential threshold changes in three months after receiving the device in children with cochlear implant

In neural response telemetry (NRT), intracochlear electrodes stimulate the auditory nerve and record the neural responses. The electrical stimulation send to the auditory nerve by an electrode and the resulted response, called electrically evoked compound action potential (ECAP), is recorded by an adjacent electrode. The most important clinical applications of this test are evaluation and monitoring the intra and postoperative responses of auditory nerve and help to primary setting of speech processor. The aim of this study was evaluating of the potential's threshold changes in three monthes after receiving the devise in pediatric cochlear implant recipients. This longitudinal study evaluated the potential's threshold in four given electrodes in four sessions after receiving the device by approximately one months intervals in children implanted in Amir Alam and Hazrat-e-Rasoul hospitals in 2007, July to December. ECAP mean threshold level of each electrode did not significantly change in differnent sessions, while there was significant difference between apical and basal electrode's responses in every session(p<0.001). The reliabiliy of the responses result in more certainty of clinician to fit the speech processor for a long time. Better responses in apical electrodes may lead to develope an effective coding strategy.