[Compare NRT threshold and behavior T-level in cochlear implant patients].

OBJECTIVE

To learn the relationship between neural response telemetry(NRT) threshold and behavior T-level in cochlear implants patients and to learn how can we made NRT more useful for us to get the best map for cochlear implants who could not cooperate well to get the accurate behavior T-level.

METHOD

Seventy-seven children implanted with the cochlear Nucleus 24 system. At each mapping procedure, vNRT threshold and behavior T-level of electrodes 1, 6, 11, 16, 20 were tested. After a time of experience and training, the children could cooperate well for test and the behavior T-level can be used for mapping. At the same time, vNRT and behavior T-level of the same electrode were recorded for statistic analysis.

RESULT

Correlation coefficients (r) of vNRT and behavior T-level of each electrode were ranged from 0.40 to 0.54 respectively. The vNRT across each electrode ranged from 135 microV to 215 microV and the behavior T-level of each electrode ranged from 120 CL to 190 CL. The mean difference between vNRT and behavior T-level of electrode 1, 6, 11, 16, 20 were 27 +/- 14, 24 +/- 13, 31 +/- 14, 26 +/- 13, 20 +/- 13 respectively. The maximum difference between vNRT and behavior T-level was 65 and the minimum was -15. The group mean T-level is ranged from 148 CL to 159 CL and the group mean vNRT is ranged from 168 microV to 186 microV from electrodes 20 to electrodes 1. The NRT and behavior T-level both are going up higher a little bit from electrodes 20 to electrodes 1.

CONCLUSION

NRT can be used to speculate the behavior T level for young child and adults who can not do behavior test. But because of the large individual difference, the result will not always be accurate. So, behavior T-level test should be the first choice for cochlear mapping patients.