Definition of parameters
We defined a reproducible middle-latency biphasic wave as the effective wave type. The waveforms with missing amplitude and unreproduced waves were rejected. P1 and N1 were the first positive and negative peaks, respectively. The P1 and N1 latencies (the interval between 0 ms and the corresponding maximal peak) were calculated by the interval between P1 and N1, and the rectified amplitude (the vertical distance between the P1 and N1 peaks) was recorded. The results were reviewed before and 1–3 months after CI. No significant change in VEMP was defined as no change; disappeared VEMP was defined as clear waveform before CI but waveform disappeared after the implantation.