Absent Intraoperative Electrically Evoked Compound Action Potential Results during Cochlear Implant Surgery: Our Experience

Intraoperative electrically evoked compound action potential (ECAP) testing during cochlear implant surgery is used to assess the integrity of implant, proper placement of electrode array, auditory nerve stimulation and to use as a preliminary tool to start a map, especially for difficult-to-test population. Sometimes, irrespective of normal or abnormal anatomical structure of the inner ear, ECAP response can be absent in one or more recording electrodes intraoperatively due to many factors. This report presents four pediatric cases who underwent cochlear implantation at our center. One of the cases had a hypoplastic auditory nerve and the rest had normal inner ear anatomy. Intraoperatively, two of the cases had absent neural responses in all the electrodes whereas in the remaining two absent neural response was found in single and in three basal electrodes. Postoperatively, in all the cases, neural response had recovered, except the one with hypoplastic nerve, which recovered only in few electrodes.