声诱发的短潜伏期负反应与前庭诱发的肌源性电位关系初步研究

目的研究声诱发的短潜伏期负反应(acoustically evoked short latency negative response,ASNR)的特点,并初步证实该电位的前庭源性,即与前庭诱发的肌源性电位(vestibular evoked myogenic potentials,VEMP)同源。方法分别检测28例健康成人、16例前庭疾病和1例全聋患者的VEMP和ASNR,比较ASNR与VEMP之间的关系。结果ASNR正常引出率为87.5%,潜伏期正常值为3.50±0.25ms;2倍标准差作为正常值的上、下限,ASNR潜伏期的范围为3~4ms,阈值为80~90dB nHL。16例前庭疾病患者均行双侧检查,在VEMP消失的9耳(9例)中,ASNR均未引出;VEMP低振幅的8例(8耳)中,5例(5耳)未引出ASNR,3例(3耳)ASNR正常引出。5例梅尼埃病患者接受甘油试验,1例(2耳)甘油试验前后VEMP与ASNR均正常,2例(4耳)双侧VEMP与ASNR甘油试验前异常,甘油试验后正常,1例(1耳)患侧VEMP正常,甘油试验前后无变化,ASNR由异常变为正常;1例(2耳)VEMP甘油试验前双侧异常,甘油试验后正常,但ASNR均未引出。1例听力正常的前庭神经炎患者,患侧VEMP未引出,ASNR电位也未引出。1例先天性全聋患者人工耳蜗植入前,VEMP、ASNR正常引出;植入后,术侧VEMP振幅降低,ASNR未引出。结论ASNR与VEMP可能均源于球囊。鉴于目前的结果,在不便进行VEMP检测时可用ASNR替代。     

听神经瘤患者前庭诱发肌源性电位的特征

目的:建立听力室前庭诱发肌源性电位(VEMP)潜伏期、振幅等参数的正常值,探讨VEMP对听神经瘤(AN)诊断的意义.方法:以短声为刺激声,双耳给声,双侧胸锁乳突肌分别记录VEMP.选取46例听力正常的健康人群,记录VEMP,建立VEMP正常值;2006～2007年收治的14例AN患者,除听觉脑干反应(ABR)和前庭冷热实验外,记录并分析VEMP的各项参数.结果:46例听力正常者中,43例双耳均可引出VEMP,3例双耳均不能引出,引出率为93.5%(86/92).VEMP正常值参数分别为:p13潜伏期(11.86±2.11)ms,n23潜伏期(18.57±2.19)ms,p13n23间期(6.71±1.69)ms,p13n23振幅(24.18±8.22)μV;耳间差各参数分别为:p13潜伏期耳间差(|△p13|)(0.64±0.61)ms,n23潜伏期耳间差(|△n23|)(1.05±0.97)ms,p13n23间期耳间差(|△p13n23|)(0.84±0.81)ms,振幅比1.32±0.37,耳间不对称率0.12±0.11.14例AN患者中,3例两侧均未引出VEMP,8例健侧正常患侧未引出,3例健侧正常患侧VEMP表现为p13、p13n23间期的耳间差延长.结论:VEMP可作为听神经瘤的筛查方法,联合其他检查可提高听神经瘤的检出率.     

儿童单侧听神经病附三例分析

目的 探讨儿童单侧听神经病的听力学特征。方法 对3例单侧听神经病患儿进行纯音听阈(PTT)、声反射(AR)、听性脑干反应(ABR)和畸变产物耳声发射(DPOAE)检查，并对其结果进行综合分析。结果 3例患儿的PTT均呈1侧耳听力正常，另1侧耳听力丧失。健耳的同侧和交叉AR能引出，患耳的同侧和交叉AR未能引出。健耳的ABR各波潜伏期正常，患耳的ABR各波未能引出。双耳DPOAE各频率反应幅值正常。结论：DPOAE正常或基本正常，PTT、AR和ABR异常是听神经病的重要特征。单侧听神经病的听力学特征与双侧听神经病基本一致。对儿童表现为单侧感音神经性聋者宜进行系统的听力学检查，以期作出正确的诊断。     

单侧听神经病附三例报告

目的　探讨单侧听神经病的听功能特征及病损部位。方法　报告及分析 3例患者的临床资料、纯音测听、声导抗测试、畸变产物耳声发射 (DPOAE)、听性脑干反应 (ABR)检测结果。结果　 3例单侧患耳纯音听力图分别为上升型、平坦型及下降型 ,听力损失 1例为中度 ,2例为重度 ,另侧听力图正常 ;3例患者双侧DPOAE正常引出 ,而ABR患侧未能引出 ,健侧正常引出。颞骨HRCT未见异常。结论　单侧听神经病的听功能特征与双侧听神经病的听功能特征相同。诱发性耳声发射及ABR对鉴别一般感音神经性聋与中枢性聋有重要意义。病损部位可能在内毛细胞至听神经的传入通路     

经眼前庭诱发肌源性电位检查在梅尼埃病患者中的应用

目的:评价经眼前庭诱发肌源性电位(oVEMPs)检查在梅尼埃病诊断中的应用价值。方法:对30例健康受试者和27例单侧梅尼埃病患者进行临床听力学检测和经眼外肌连接的oVEMPs检查,分别测量2组的潜伏期、振幅以及耳间振幅差比值。结果:oVEMPs检查结果显示,30例健康受试者的oVEMPs均引出正常波形,n10波的潜伏期为(10.13±0.48)ms,p15波的潜伏期为(15.23±0.46)ms,n10和p15的波间振幅为(6.58±2.65)μV;梅尼埃病患者oVEMPs异常8例,正常19例。结论:oVEMPs检查快速、安全、客观,可重复性好;在梅尼埃病的诊断中有一定的临床应用价值。     

梅尼埃病眼肌前庭诱发肌源性电位的临床研究

目的通过对梅尼埃病(Meniere disease,MD)患者眼肌前庭诱发肌源性电位(ocular vestibular-evoked myogen-ic potential,o VEMP)结果进行分析,进一步探讨梅尼埃病患者o VEMP的临床特征。方法对66例梅尼埃病患者及27例年龄、性别与之匹配的健康人进行o VEMP测试,分析对比oVEMP的引出率及各参数指标。结果 oVEMP在病例组患侧的引出率为41.7%、健侧为55%,对照组为100%;患侧与健侧比较差异无统计学意义(P>0.05),患侧、健侧与对照组比较差异均有统计学意义(P<0.05)。病例组患侧、健侧及对照组间o VEMP的振幅及不对称比均有统计学差异(P<0.05),然各波潜伏期相比无统计学意义。整体来讲,梅尼埃病患者oVEMP引出率随听力学分期升高而呈逐渐下降趋势。结论梅尼埃病患者无论健侧还是患侧,其oVEMP异常均较显著,且以患侧变化显著,提示MD患者的椭圆囊功能受损,oVEMP可用于评估MD患者椭圆囊功能,且进一步对其诊疗作出指导。     

前庭诱发的肌源性电位临床应用

前庭诱发的肌源性电位（Vestibular evoked myogenic potentials，VEMP）可用于评价球囊功能及其对称性。本文总结VEMP在神经耳科学中的应用情况。首先建立VEMP的临床适用的检查方法，这些方法包括：刺激声的选择、刺激强度及给声方式，建立VEMP在振幅、阈值、潜伏期和耳间潜伏期的正常值。临床上常用于：梅尼埃病和迟发性膜迷路积水、前庭神经炎、听神经瘤、前半规管裂综合征和听神经病的诊断定位。VEMP的振幅变化较大．潜伏期的变化较大，而阈值较稳定。梅尼埃病和迟发性膜迷路积水、前庭神经炎、听神经瘤可以出现振幅的异常或引不出；梅尼埃病、迟发性膜迷路积水和听神经瘤可见振幅和潜伏期异常。听神经瘤还可见耳间潜伏期延长。听神经病主要表现为振幅的异常，振幅减低或引不出。VEMP是一种稳定的肌源性电位，双侧声刺激较为适宜。VEMP的阈值检查主要用于压力或声音敏感性眩晕；耳间潜伏期的异常主要见于桥一小脑角占位病变：振幅和潜伏期的异常一般没有特异性．可见于累及前庭下神经的病变。     

单侧及双侧短纯音刺激前庭诱发肌源性电位观察

目的:比较正常人单、双侧短纯音刺激的前庭诱发肌源性电位 (vestibular evoked myogenic potential,VEMP)的反应特性,以用于临床球囊功能及其对称性的检测。方法:对86名年龄18～50岁的正常人分别在单、双侧短纯音(500Hz)刺激下测定VEMP的引出率、潜伏期、振幅、耳间潜伏期差、耳间振幅比和耳间不对称率。结果:双侧及单侧给声侧VEMP引出率为100％,对侧未给声侧为45． 9％。双侧与单侧给声侧p13及n23的潜伏期均值分别为17．29±2． 17、24．98±2．67、17．39±1．94和25．65±3．28ms,两种刺激方式下无明显差异,但均与对侧未给声侧差异显著(P<0．05)。双侧短纯音刺激振幅均值与单侧给声侧有显著性差异(P<0．05),与对侧未给声侧有高度显著性差异(P<0．01),分别为123．35±73．06、 150．05±76．58、84．02±55．80 μ V。单、双侧短纯音刺激耳间振幅比,耳间潜伏期差以及耳间不对称率均有显著性差异(P<0．05, P<0．01,P<0．01),单侧声刺激时对侧未给声侧潜伏期较给声侧延长。结论:单侧给声侧、双侧短纯音刺激VEMP的引出率、潜伏期无明显差异,但振幅、耳尖潜伏期差、耳间振幅比和耳间不对称率     

单侧梅尼埃病患者双侧耳蜗电图检查的意义

目的分析梅尼埃病患者双侧耳蜗电图,以早期发现一侧梅尼埃病对侧耳膜迷路积水的可能性,了解梅尼埃病患者对侧无症状耳内淋巴积水可能的发生率。方法对明确诊断为梅尼埃病的121例患者行双侧耳蜗电图检查,对其中可统计出明确病程的114例比较其双侧耳蜗电图结果与病程的关系。结果可以统计出梅尼埃病病程的114例中,单侧异常46例,平均病程7.42±7.68年(5天~37年);双侧异常38例,平均病程5.43±5.73年(3个月~20年);双侧正常者30例,平均病程5.37±4.40年(4个月~12年)。三种情况下,病程与耳蜗电图结果无直线相关(P>0.05)。在121例行双侧耳蜗电图检查的病例中,双侧耳蜗电图异常者39例,其中9例有双侧耳鸣,占23.1%(9/39),而单侧耳蜗电图异常者51例中,出现双侧耳鸣的仅有1例,占2%(1/51),双侧耳蜗电图异常伴双侧耳鸣的发生率明显高于单侧耳蜗电图异常伴双侧耳鸣的发生率(P<0.01)。结论耳蜗电图对梅尼埃病诊断的评价应建立在对梅尼埃病动态变化的理解基础之上;耳蜗电图对早期听力正常的梅尼埃病的诊断具有一定的参考价值。     

小剂量庆大霉素鼓室内注射治疗梅尼埃病对球囊功能的影响

摘要：目的应用颈性前庭诱发肌源性电位（cVEMP）研究小剂量庆大霉素鼓室内注射对球囊功能的影响,以指导临床用药。方法回顾性分析2016年5月—2018年10月行耳内镜下鼓室内注射庆大霉素（30 mg/mL）治疗的26例单侧梅尼埃病患者,于注射前及注射后3周分别行纯音听阈测试（PTA）及cVEMP检查,比较注射前后患者听力及cVEMP结果。结果26例梅尼埃病患者随访12~24个月,眩晕控制率为92.31%（24/26）。注射前患耳平均气导听阈为（61.80±2.79）dBHL,注射后为（64.40±2.51）dBHL,注射前后听力差异无统计学意义（P>0.05）。cVEMP检查提示注射前4例（15.38%）未引出,22例注射前患侧P1平均潜伏期为（16.51±2.46）ms,N1平均潜伏期为（27.57±3.36）ms;注射后12例（46.15%）未引出,其他14例P1平均潜伏期为（18.88±1.84）ms,N1潜伏期（30.57±1.45）ms。可见注射后引出率下降,P1、N1潜伏期延长。注射前后患侧P1、N1潜伏期的结果差异具有统计学意义（P<0.05）。结论鼓室内注射小剂量庆大霉素可抑制或破坏球囊功能,cVEMP检查有助于评价此治疗的有效性及安全性。     

前庭诱发的肌源性电位耳间潜伏期差异及意义

目的:探讨前庭诱发的肌源性电位(VEMP)耳间潜伏期(IAL)差值的意义,提高VEMP检查的敏感性。方法:健康成人20例及双侧VEMP引出的听神经瘤或桥小脑角肿瘤患者13例和多发性硬化症患者1例,采用双耳短声记录VEMP,并分析|Δp13|、|Δn23|和|Δp13-n23|(分别代表IAL差值的绝对值)。结果:健康成人|Δp13|上限为1.13ms;|Δn23|为1.38ms;|Δp13-n23|为1.54ms。|Δp13-n23|左侧与右侧差异无统计学意义(P>0.05)。IAL差值|Δp13|、|Δn23|和|Δp13-n23|可提供p13、n23潜伏期所不能提供的异常信息。结论:VEMP|Δp13|、|Δn23|和|Δp13-n23|,尤其是|Δp13|同潜伏期一样提示其传导通路异常,是一项实用的指标,可作为临床对于VEMP异常判断的辅助指标。     

Influence of thresholds on amplitudes in vestibular evoked myogenic potentials

Objectives

To investigate the relationship between the threshold and the interaural amplitude difference ratio (IADR) in cervical vestibular evoked myogenic potential (cVEMP) testing and pursuit the clinical significance of the parameters.

Materials and methods

cVEMP responses were recorded while the SCM contraction was controlled using a pressure cuff. The intensities of the sound stimulation decreased from 95 dB nHL by 5 dB, until no responses were evoked. Thresholds, interaural threshold difference (ITD), amplitudes, and interaural amplitude difference ratio at the stimulation of 95 dB nHL were calculated and the relationship between them was examined.

Results

All subjects showed cVEMP responses bilaterally. Thresholds measured were overall 76 dB nHL and most (92%) ears showed the ITD of 0 or 5 dB. The amplitudes of cVEMP responses showed a positive correlation with the sound intensities, and more specifically with the sound intensity above each threshold value. There was no significant difference in IADR values by the ITD.

Conclusions

Based on our study, the ITD is less than 10 dB in most normal subjects and estimation of threshold should be added to cVEMP testing for probing vestibular asymmetry. Getting a threshold might be helpful in determining whether the abnormal interaural amplitude difference ratio is related to the abnormal ITD.     

Correlation between bithermal caloric test results and vestibular evoked myogenic potentials (VEMPs) in normal subjects

Bithermal caloric testing and vestibular evoked myogenic potentials (VEMPs) are both diagnostic tools for the study of the vestibular system. The first tests the horizontal semicircular canal and the second evaluates the saccule and lower vestibular nerve. The results of these two tests can therefore be expected to be correlated. The aim of this study was to compare bithermal caloric test results with VEMP records in normal subjects to verify whether they are correlated. Material and method: A prospective study was conducted in 60 healthy subjects (30 men and 30 women) who underwent otoscopy, pure tone audiometry, bithermal caloric testing and VEMPs. From the caloric test, we assessed the presence of possible vestibular hypofunction, whether there was directional preponderance and reflectivity of each ear (all based on both slow phase velocity and nystagmus frequency). The analysed VEMPs variables were: p1 and n1 latency, corrected amplitude, interaural p1 latency difference and p1 interaural amplitude asymmetry. We compared the reflectivity, hypofunction and directional preponderance of the caloric tests with the corrected amplitudes and amplitude asymmetries of the VEMPs. No correlations were found in the different comparisons between bithermal caloric testing results and VEMPs except for a weak correlation (p = 0.039) when comparing preponderance based on the number of nystagmus in the caloric test and amplitude asymmetry with 99 dB tone burst in the VEMPs test. The results indicate that the two diagnostic tests are not comparable, so one of them cannot replace the other, but the use of both increases diagnostic success in some conditions.     

The influence of clicks versus short tone bursts on the vestibular evoked myogenic potentials

OBJECTIVE: Vestibular evoked myogenic potential (VEMP) has become a diagnostic tool to evaluate the integrity of sacculo-collic reflex. To obtain a more consistent VEMP response in normal-hearing subjects, we examine whether clicks or short tone bursts are more effective in eliciting VEMP responses. DESIGN: Prospective study. Twenty-nine normal-hearing volunteers (58 ears) were given VEMP tests. Clicks and short tone bursts were presented alternately to evoke VEMPs. The latencies of peak p13 and n23, peak-to-peak interval and amplitude (p13-n23) were measured and compared. RESULTS: Click stimulation of 57 ears (98%) produced VEMPs (C-VEMPs), whereas 51 (88%) revealed positive short tone burst-evoked VEMPs (STB-VEMPs), exhibiting a significant difference (p < 0.05). Furthermore, C-VEMPs displayed shorter latency, longer interval and larger amplitude than STB-VEMPs, with a significant difference (p < 0.05), respectively. CONCLUSIONS: C-VEMPs had a higher response rate, shorter latency, and larger amplitude than STB-VEMPs. These findings suggest that click is superior to short tone burst to trigger VEMPs. Because C-VEMPs have a shorter p13 latency than STB-VEMPs, the interpretation of prolonged latency differs in each stimulus condition.     

Effect of click duration on vestibular-evoked myogenic potentials

CONCLUSIONS: The 0.5-VEMP demonstrated a more prominent waveform morphology than either the 0.1- or 0.2-VEMPs. In addition, the 0.5-VEMP had smaller interaural latency differences than the 1.0-VEMP. These findings suggest that 0.5 ms is superior to other click durations in terms of yielding VEMP responses for clinical use. OBJECTIVE: In order to establish the ideal stimulus condition for vestibular-evoked myogenic potentials (VEMPs), we studied the use of various click durations to generate different response patterns in normal subjects. The influence of click durations on VEMPs is described and the optimal stimulation duration for clinical use is suggested. MATERIAL AND METHODS: This was a prospective study. Eighteen healthy volunteers (36 ears) underwent VEMP tests. Four click durations (0.1, 0.2, 0.5 and 1.0 ms) were used in a random order to elicit VEMP responses (0.1-, 0.2-, 0.5- and 1.0-VEMP, respectively). The latency of each peak (p13, n23), the peak-to-peak interval and amplitude (p 13-n23) and the relative amplitude (defined as the amplitude divided by that of the 0.5-VEMP) were measured and compared. RESULTS: Click stimulation of 34 ears (94%) produced 0.1-VEMP responses, whereas positive 0.2-, 0.5- and 1.0-VEMP responses were observed in 36 (100%). The latencies of peaks p13 and n23 were significantly prolonged between successive stimulus durations from 0.1 to 1.0 ms (p <0.05), in contrast to the p13-n23 intervals (p >0.05). The 1.0-VEMP displayed the largest SDs of latencies and interval among the four different VEMPs. The relative amplitude was significantly increased between successive durations from 0.1 to 0.5 ms (alphaT <0.05), but there was no significant difference between 0.5 and 1.0 ms (alphaT >0.05).     

Sound source localization

Sound source localization is paramount for comfort of life, determining the position of a sound source in 3 dimensions: azimuth, height and distance. It is based on 3 types of cue: 2 binaural (interaural time difference and interaural level difference) and 1 monaural spectral cue (head-related transfer function). These are complementary and vary according to the acoustic characteristics of the incident sound. The objective of this report is to update the current state of knowledge on the physical basis of spatial sound localization.     

Vestibular evoked myogenic potentials in newborns

This study presents a novel method for recording vestibular evoked myogenic potential (VEMP) in newborns, used to investigate the maturation of sacculocollic reflex at birth.Twenty full-term newborns aged 2-5 days old were enrolled in this study. During natural sleep, each newborn underwent distortion product otoacoustic emission test, and VEMP test using the head rotation method. For comparison, 20 healthy adults also underwent VEMP test using the same method. Based on adult criteria, 40 newborn ears revealed normal VEMPs in 40%, prolonged VEMPs in 35%, and absent VEMPs in 25%, indicating that great variation exists in the maturation of the sacculocollic reflex at birth. Comparison of VEMP characteristics between healthy newborns and adults revealed nonsignificant difference in the response rate and the latency of n23. However, significant differences existed in the latency of p13, interpeak p13-n23 interval and p13-n23 amplitude between newborns and adults. In conclusion, VEMPs in newborns can be easily recorded by the head rotation method. Prolonged or absent VEMPs in newborns may reflect incomplete maturity of the sacculocollic reflex pathway, especially the myelination. A further large number of newborns receiving MRI scan for other reasons may undergo VEMP test to verify this hypothesis.     

Clinical Value of Vestibular Evoked Myogenic Potential in Assessing the Stage and Predicting the Hearing Results in Ménière's Disease

Objectives

Our goal was to find the clinical value of cervical vestibular evoked myogenic potential (VEMP) in Ménière''s disease (MD) and to evaluate whether the VEMP results can be useful in assessing the stage of MD. Furthermore, we tried to evaluate the clinical effectiveness of VEMP in predicting hearing outcomes.

Methods

The amplitude, peak latency and interaural amplitude difference (IAD) ratio were obtained using cervical VEMP. The VEMP results of MD were compared with those of normal subjects, and the MD stages were compared with the IAD ratio. Finally, the hearing changes were analyzed according to their VEMP results.

Results

In clinically definite unilateral MD (n=41), the prevalence of cervical VEMP abnormality in the IAD ratio was 34.1%. When compared with normal subjects (n=33), the VEMP profile of MD patients showed a low amplitude and a similar latency. The mean IAD ratio in MD was 23%, which was significantly different from that of normal subjects (P=0.01). As the stage increased, the IAD ratio significantly increased (P=0.09). After stratification by initial hearing level, stage I and II subjects (hearing threshold, 0-40 dB) with an abnormal IAD ratio showed a decrease in hearing over time compared to those with a normal IAD ratio (P=0.08).

Conclusion

VEMP parameters have an important clinical role in MD. Especially, the IAD ratio can be used to assess the stage of MD. An abnormal IAD ratio may be used as a predictor of poor hearing outcomes in subjects with early stage MD.     

健康青年人经眼前庭诱发肌源性电位检查

目的评价经眼外肌引出的前庭诱发肌源性电位的临床应用价值。明确潜伏期、振幅以及相关参数的正常范围。方法选择40例体格检查和纯音听阈、中耳分析结果正常且无眩晕发作史的健康志愿者,用500 Hz的click声刺激进行经眼外肌连接的前庭诱发肌源性电位(ocular-vestibular evoked myogenic potentials,oVEMPs)检查。结果 40名健康受试者均能引出稳定波形,引出率100%。n10潜伏期:左侧(9.76±0.48)ms,右侧(9.83±0.47)ms;振幅(6.34±0.39)μV。p15潜伏期:左侧(15.24±0.44)ms,右侧(15.14±0.45)ms;振幅(5.72±0.57)μV。n10的耳间振幅差比值0.02～0.29。结论 oVEMPs检查方法操作简单,用时短,不诱发眩晕,结果客观,可重复性好。     

Comparison of the diagnostic value of 3 T MRI after intratympanic injection of GBCA, electrocochleography, and the glycerol test in patients with Meniere's disease

Conclusions The 0.5-VEMP demonstrated a more prominent waveform morphology than either the 0.1- or 0.2-VEMPs. In addition, the 0.5-VEMP had smaller interaural latency differences than the 1.0-VEMP. These findings suggest that 0.5 ms is superior to other click durations in terms of yielding VEMP responses for clinical use.

Objective In order to establish the ideal stimulus condition for vestibular-evoked myogenic potentials (VEMPs), we studied the use of various click durations to generate different response patterns in normal subjects. The influence of click durations on VEMPs is described and the optimal stimulation duration for clinical use is suggested.

Material and methods This was a prospective study. Eighteen healthy volunteers (36 ears) underwent VEMP tests. Four click durations (0.1, 0.2, 0.5 and 1.0 ms) were used in a random order to elicit VEMP responses (0.1-, 0.2-, 0.5- and 1.0-VEMP, respectively). The latency of each peak (p13, n23), the peak-to-peak interval and amplitude (p13-n23) and the relative amplitude (defined as the amplitude divided by that of the 0.5-VEMP) were measured and compared.

Results Click stimulation of 34 ears (94%) produced 0.1-VEMP responses, whereas positive 0.2-, 0.5- and 1.0-VEMP responses were observed in 36 (100%). The latencies of peaks p13 and n23 were significantly prolonged between successive stimulus durations from 0.1 to 1.0 ms (p<0.05), in contrast to the p13-n23 intervals (p>0.05). The 1.0-VEMP displayed the largest SDs of latencies and interval among the four different VEMPs. The relative amplitude was significantly increased between successive durations from 0.1 to 0.5 ms (α_T<0.05), but there was no significant difference between 0.5 and 1.0 ms (α_T>0.05).