A Study: The Relationship Between The Differecnces Of Wave ? Latency And ?-? Inter-peak Latency In ABRs With High And Low Stimulion Rates

Objective(1)To calculate the incidence of absence of wave ?,and analyze its relationship with stimulation rate and age respectively.(2)To study the relationship between the differences of wave ? latency and ?-? inter-peak interval in both high and low stimulation rates ABR and to discuss the diagnostic aggreement of using the wave ? latency difference in diagnosing posterior circulation ischemia when wave ? is absent.Method(1)314 subjects(628 ears)were randomly selected between January 2016 and September 2016 from the Audiology and ?estibular Center at The Affiliated Hospital of School of Medicine of Ningbo University.There were males with an average age of 50.9±15.8,and the remaining 119 subjects were females with an average age of 53.0±13.5.The equipment used to assess ABR was the Smart EP ABR system from ?ntelligent Hearing Systems(USA).The recording,reference and ground electrodes were placed on the forehead,the ipsilateral mastoid and the low forehead.Subjects were required to lie on the back quietly with closed eyes and smoothed breath.Other parameters were inter-electrode impedance?3.0k?,an alternating click stimulus,stimulus intensity at 80 d Bn HL,1024 average sweeps and a time window of 10 ms.ABR was carried out in each case using both high and low stimulation rates(51.1/s and 11.1/s),then the incidence of absence of wave ? was calculated and analyzed further as to its relationship with stimulation rate and age respectively.(2)237 subjects(316 ears)were randomly selected between October 2015 and December 2016 from the Audiology and ?estibular Center at The Affiliated Hospital of School of Medicine of Ningbo University.Wave ? and ? were present for all these subjects and they were separated into two groups: normal ?-? wave latency difference group and abnormal ?-? wave latency difference group,i.e.?-? wave latency difference ?0.28 ms vs >0.28 ms.79 subjects(158 ears)were in the normal group,20(40 ears)of which were males and 59(118 ears)were females with an averageage of 46.6±13.7.158 ears were in the abnormal group with a ?-? wave latency difference >0.28 ms,51 were males and 107 were females aged 47.6±13.1 as a mean.same method as experiment 1.The differences of wave ? latencies and ?-? inter-peak intervals were calculated and analyzed using Pearson analysis.Results(1)The incidence of absence of wave ? in the low stimulation rate is 20.54% whereas 30.41% for the high stimulation rate,suggesting that the incidence of absence of wave ? is increased as the stimulation rate increased(P<0.05).(2)The incidence of the absence of wave ? is increased with an increase in age(P<0.001).(3)Pearson correlation coefficient between the differences of wave ? latencies and the differences of ?-? inter-peak interval is 0.628,with a P value <0.001.As for the difference of wave ? latencies,its area under the DOC(i.e.AUC)is 0.819(P<0.001)and its corresponding threshold is 0.34 ms.Conclusion The incidence of the absence of Wave ? is increased with an increase in stimulation rate and age.There is a highly positive correlation and diagnostic agreement between the differences of wave ? latencies and the differences of ?-? inter-peak intervals in high and low stimulation rates ABR,indicating that the difference of wave ? latency could be used instead of ?? inter-peak interval as an alternative tool of diagnosing posterior circulation ischemia.?n clinical settings,it is relatively reliable to use the difference of wave ? latency in cases when wave ? could not be elicited.