Four patients (2 children and 2 adults) with the Nucleus 24 cochlear implant showed no electrically evoked compound action potential (EAP) in intra-operative neural response telemetry (NRT) measurements. The causes of hearing impairment were congenital sensorineural hearing loss, inner ear anomaly, ossified cochlear due to sepsis and progressive sensorineural hearing loss. Three cases with no EAP in the intraand post-operative NRT measurements revealed poor post-operative speech cognition despite having measurable behavioral T and/or C levels. Consistent poor intra- and post-operative NRT response may predict poor post-operative speech cognition. On the other hand, one case with good speech cognition immediately after operation presented apparent EAPs 4 months after operation.
Some cases with discrepancy between intra-operative NRT results and post-operative auditory outcome may demonstrate significant EAPs within several months after operation.
