| Part I analysis of intra-operative EABR characteristics under the conditions of different pulse width in cochlear implant recipientsObjective:To compare the intra-operative electrical evoked auditory brain stem response(EABR) characteristics under the conditions of different pulse width, analysis the relationship of pulse width with EABR wave V lead-out rate and threshold, summarize the affects of different pulse width conditions on EABR wave V lead-out rate and threshold, and select optimized EABR pulse width test parameters.Method:A study was performed on24patients with no residual hearing (12cases with normal cochlear,4cases with LVAS,4cases with Mondini deformation,2cases with common cavity deformation,2cases with internal auditory canal stenosis)(test group) matched with24implantees with residual hearing (control group). With modified Freedom cochlear implant and ball-end platinum-iridium wire electrode, the two groups were given the electrical stimulation of50μs,100μs and200μs pulse width, recording EABR wave V lead-out rate and the threshold under the conditions of different pulse width with Bio-logic Navigator Pro evoked potential instrument.Result:EABR wave V lead-out rate of the test group(91.7%、91.7%and91.7%) was lower than that of the control group(100%、100%and95.8%),while the threshold of the test group(183.73±8.96CL、151.28±10.05CL、120.56±12.82CL) was higher than that of the control group (175.50±9.14CL、142.71±11.45CL、110.63±10.24CL) and differences were statistically significant.(P<0.05, t=18.87、16.82and17.64)Conclusion:Intra-cochlear monopolar stimulation can induce good EABR waveform. Patients with no residual hearing EABR threshold are significantly higher than in patients with residual hearing. EABR wave V lead-out rate under pulse width50μs and100μs was higher than that under pulse width200μs. EABR waveform differentiation was better under pulse width50μs, severe deformity may need to increase the amount of stimulation (pulse width instead of100μs). PartⅡ analysis of intra-operative EABR characteristics under the conditions of different stimulation rate in cochlear implant recipientsObjective:To compare the intra-operative electrical evoked auditory brain stem response(EABR) characteristics under the conditions of different stimulation rate, analysis the relationship of stimulation rate with EABR wave Ⅴ lead-out rate, summarize the affects of different stimulation rate conditions on EABR wave Ⅴ lead-out rate, select optimized EABR stimulation rate test parameters, and compare the EABR threshold value and latency. Method:A study was performed on16patients with no residual hearing (10cases with normal cochlear,3cases with LVAS,2cases with Mondini deformation,1cases with common cavity deformation)(test group) matched with16implantees with residual hearing (control group). The two groups were given the electrical stimulation rate of23Hz、35Hz and70Hz, recording EABR wave Ⅴ lead-out rate under the conditions of different stimulation rate. Result: EABR wave Ⅴ lead-out rate of the two groups was100%under the conditions of23Hz.EABR wave Ⅴ lead-out rate of the test group(87.5%and68.8%) was lower than that of the control group(93.8%and87.5%) under the conditions of35Hz and70Hz. The threshold of the test group(180.1±6.33CL) was higher than that of the control group (172.50±8.37CL) and differences were statistically significant.(P<0.05, t=8.85),while the difference of EABR wave Ⅴ latency between two groups was not statistically significant.(P=0.80t=0.27) Conclusion:The cochlear with malformations is more sensitive to the changes of the stimulation rate. Pulse width mainly affects EABR threshold and waveform differentiation, while stimulation rate mainly affects EABR wave Ⅴ lead-out rate, lower stimulation rate inducing higher EABR wave Ⅴ lead-out rate. The pulse width50us and stimulation rate23Hz is an ideal stimulus condition. Part III Evaluation of intra-operative EABR characteristics and rehabilitation effects of cochlear implantation in patients with internal auditory canal stenosisAbstract Objective:To investigate the intra-operative electrical evoked auditory brain stem response(EABR) characteristics and the hearing and speech rehabilitation effects of cochlear implantation(CI) in patients with internal auditory canal stenosis(IACS). Method:A retrospective study was performed on16patients with IACS(IACS group) matched with16implantees without IACS(control group),who received multi-channel CI because of pre-lingual sensorineural hearing loss. The integrity and functional status of the auditory pathway were assessed by EABR, recording waveforms, threshold sand dynamic ranges intra-operation before Cl. Interviewed the implantees’ parents or teachers, asking them to rate the implantees’ hearing and speech ability according to Categories of Auditory Performance(CAP)and Speech Intelligibility Rating(SIR).Paired T test was performed to compare scores of CAP and SIR between before and1year after CI, while Spearman test was performed to compare correlation between EABR grades and post-operative CAP scores. Result: Among the IACS group,2cases weren’t recorded typical EABR waveforms and without auditory response1year after a successful CI. The EABR waveforms in the IACS group were poorer than that in the control group, their EABR thresholds higher than the control group, and their EABR dynamic ranges less than the control group. The hearing and speech rehabilitation after CI showed that the results of CAP and SIR values (3.47±1.09and1.62±0.50) scored significantly lower than the control group(5.06±0.79and2.59±0.58)(P<0.05), but significantly increased compared with pre-operation. Intra-operative EABR grades and post-operative CAP scores showed significant correlation(r=0.78, P<0.05). Conclusion:Intra-operative EABR can accurately monitor the integrity and functional status of the auditory pathway, be of important clinical value in predicting whether patients can acquire auditory responses with the aid of CI. CI can help patients with IACS to improve the ability of hearing and speech with EABR to screen out compatible implantees. |
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