气导声刺激前庭诱发肌源性电位在正常儿童中的表现

目的 探讨研究正常儿童中气导声刺激诱发的眼性前庭诱发肌源性电位(oVEMP)和颈性前庭肌源性诱发电位(cVEMP)的各项参数指标,并对正常值进行统计学处理分析。 方法 选择4~10岁听力正常健康儿童52例,以500 Hz短纯音作为刺激音,分别行 oVEMP和cVEMP检测,记录左、右耳引出率及波形参数,并采用SPSS统计软件进行统计学处理分析。 结果 双耳皆未引出oVEMP 2例,单耳可引出oVEMP4例,oVEMP总体引出率为92%。双耳皆未引出cVEMP 2例,cVEMP总体引出率为96%。oVEMP与cVEMP的P1潜伏期分别为(17.07±0.89)ms、(15.55±1.58)ms;N1潜伏期分别为(12.39±0.91)ms、(23.10±2.29)ms;N1P1间期分别为(4.68±0.88)ms、(7.83±1.56)ms;oVEMP与cVEMP的振幅分别为(7.24±4.79)μV、(197.40±118.37)μV。双耳间oVEMP及cVEMP振幅不对称比分别为(19.03±12.50)%、(22.16±18.64)%。患儿左右耳的潜伏期,P1N1间期及振幅差异无统计学意义(P>0.05)。 结论 绝大部分正常儿童经气导声刺激可引出oVEMP与cVEMP。该检测患儿依从性高,可用来评估儿童前庭功能。此研究结果可为我国的儿童气导VEMP提供正常参考值范围。     

年龄因素对直流电刺激诱发的前庭诱发肌源性电位的影响

目的 评估年龄因素对直流电刺激(GVS)诱发的颈肌前庭诱发肌源性电位(cVEMP)和眼肌前庭诱发肌源性电位(oVEMP)的影响。 方法 选择健康志愿者61名(122耳)作为研究对象,22~81岁,平均(45.0±13.8)岁。按年龄分为20~40岁组(26例,52耳)、41~60岁组(24例,48耳)以及>60岁组(11例,22耳),分别记录GVS-cVEMP和GVS-oVEMP。计算GVS-c/oVEMP在不同年龄段的引出率、阈值、潜伏期、振幅、振幅不对称比(interaural amplitude asymmetryratio,IAR),采用SPSS18.0软件进行统计学分析。 结果 GVS-cVEMP在20~40岁、41~60岁、>60岁年龄段的引出率分别为96.15%、89.58%和95.45%,组间比较差异无统计学意义(P>0.05)。GVS-oVEMP在20~40岁、41~60岁、>60岁年龄段的引出率分别为98.07%、91.67%和72.13%,随着年龄增长逐渐降低(P<0.05)。从参数分析来看,cVEMP的引出率、阈值、p1潜伏期、n1潜伏期、振幅和振幅不对称比在不同年龄组间差异无统计学意义(P>0.05);随着年龄增大,oVEMP的引出率下降、阈值增高、振幅减小(P<0.05),其他参数年龄组间差异无统计学意义(P>0.05)。 结论 随着年龄的增长,周围前庭系统的功能降低,有可能会对直流电刺激诱发的VEMP产生影响。     

健康青年人骨导前庭诱发肌源性电位临床正常值的建立北大核心CSCD

目的 建立本实验室健康青年人骨导前庭诱发肌源性电位(bone-conducted vestibular evoked myogenic potential)的临床正常值范围。方法 选择30名(60耳)健康青年人为研究对象,男15人,女15人,平均年龄(25.28±4.32)岁,使用B81骨振子进行骨导振动(bone-conducted vibration,BCV)诱发的颈肌前庭诱发肌源性电位(cervical vestibular evoked myogenic potentials,cVEMP)和眼肌前庭诱发肌源性电位(ocular vestibular evoked myogenic potentials,oVEMP)检测,以60dB nHL给声强度作为起始刺激强度,记录BCV-cVEMP和BCV-oVEMP的引出率、潜伏期、波间期、波幅和阈值,采用SPSS22.0统计软件进行统计学分析。结果 BCV-cVEMP和BCV-oVEMP的引出率均为100%(60/60);BCV-cVEMP的阈值为(41.80±2.99)dB nHL,P1、N1潜伏期分别为(16.05±1.76)ms和(26.43±2.66)ms,波间期为(10.11±2.03)ms,波幅为(86.93±60.45)μV;BCV-oVEMP的阈值为(45.00±3.50)dB nHL,P1、N1潜伏期分别为(18.25±2.40)和(12.19±2.31)ms,波间期为(6.09±0.99)ms,波幅为(10.33±9.90)μV。受试者左右耳BCVcVEMP和BCV-oVEMP的P1潜伏期(P=0.421,P=0.672),N1潜伏期(P=0.889,P=0.662),波间期(P=0.116,P=0.553),波幅(P=0.819,P=0.509)和阈值(P=0.425,P=0.090)差异均无统计学意义(P>0.05)。结论 BCV-VEMP对于健康青年人是一项稳定可靠的前庭功能检查。本实验室健康青年人BCV-VEMP正常值的建立,可为BCV-VEMP的临床应用提供参考。     

前庭诱发肌源性电位的正常人群观察

目的:观察我国正常青年人群中前庭诱发肌源性电位(VEMP)出现的阳性率及各项参数指标。方法:选取52例(男31例,女21例)21~22岁正常健康人群,以短声为刺激声,单耳给声,同侧胸锁乳突肌(SCM)记录。结果:47例2耳均可引出VEMP,5例2耳均不能引出。总104耳中,94耳阳性,10耳阴性,阳性率90%。统计阳性耳各参数:p1潜伏期(15.97±3.22)ms、n2潜伏期(24.41±2.46)ms、p1n2间期(8.41±2.06)ms,幅值(33.27±14.37)μV,阈值(93.67±5.20)dB nHL。统计47例正常人同一个体耳内差异的各参数为p1潜伏期(0.97±1.31)ms,n2潜伏期(1.23±1.30)ms,p1n2间期(0.95±1.21)ms,幅值(10.04±11.88)μV,阈值(2.29±2.56)dB nHL。男女各参数比较差异无统计学意义。结论:绝大部分正常人可引出VEMP。VEMP的引出体现该侧耳球囊→前庭下神经→脑干前庭神经核→前庭脊髓通路→颈肌运动神经元这条反射途径的完整性。VEMP可能成为一种检测前庭终器及其传导通路完整性的方法。     

骨导振动刺激诱发的前庭诱发肌源性电位

目的探讨B81骨振子在前庭诱发肌源性电位(vestibular evoked myogenic potentials, VEMPs)检测中的应用。方法对25例正常志愿者的双耳行插入式气导声刺激(air conducted sound, ACS),单侧乳突B81骨导振动刺激(bone conducted vibration, BCV)的VEMPs检查,并对ACS ,BCV VEMPs检查结果进行统计学分析。结果ACS ,BCV 眼肌前庭诱发肌源性电位(ocular vestibular evoked myogenic potentials, oVEMP)的引出率分别为92%（46/50）,98%（49/50）。BCV oVEMP与ACS oVEMP比较,两者引出率差异无统计学意义（P=0.36）;两者N1波潜伏期（P=0.00）、P1波潜伏期（P=0.00）、N1 P1波间期(P=0.01)及振幅(P=0.00)差异均具有统计学意义（P<0.05）;BCV oVEMP的N1、P1波潜伏期,N1 P1波间期均较短,而振幅较大。ACS ,BCV 颈肌前庭诱发肌源性电位(cervical vestibular evoked myogenic potential, cVEMP)的引出率均为100%（50/50）。BCV cVEMP与ACS cVEMP比较,N1波潜伏期差异无统计学意义（P=0.96）,P1波潜伏期（P=0.02）,P1 N1波间期(P=0.00)、振幅(P=0.04)均有统计学差异（P＜0.05）;BCV cVEMP的P1波潜伏期较短,P1 N1波间期较长,振幅较大。BCV oVEMP、ACS oVEMP、BCV cVEMP和ACS cVEMP的两耳间振幅不对称率（%）分别为：28.08±21.10、27.95±18.13、23.60±17.86、32.24±18.92。结论B81骨振子可以用于VEMPs的检测,骨导振动刺激在评价传导性听力损失患者的前庭耳石器功能时优于气导声刺激,可作为气导声刺激诱发VEMPs的补充检查。     

EMG修正对颈部及眼部前庭诱发肌源性电位的影响

目的研究肌电图(electromyogram,EMG)修正对前庭诱发肌源性电位(Vestibular-evoked myogenic po-tentials,VEMPs)结果产生的影响,并建立修正后的cervical Vestibular-evoked myogenic potential(c VEMP)及ocularVestibular Evoked Myogenic Potential(o VEMP)正常值范围,为临床上准确评估前庭感受器功能提供更可靠的参考依据。方法采用500Hz tone-burst刺激声对20名(40耳)听力正常且无耳蜗及前庭系统疾病的正常青年人进行c VEMP及o VEMP测试。受试者年龄为20-30岁,平均年龄(23.76±2.81)岁。测试强度为100d B n HL,通过ER-3A标准插入式耳机给声,测试时体位采取坐姿。结果所有受试者均能引出清晰可重复的c VEMP及o VEMP波形。Tone-burst c VEMP的P1潜伏期为14.13±1.97(ms),N1潜伏期为21.54±2.23(ms),幅值为1.63±0.60(μV)。Tone-burst o VEMP的N1潜伏期为10.15±0.72(ms),P1潜伏期为15.79±1.01(ms),幅值为1.38±1.02(μV)。cVEMP修正前后的振幅有显著性差异(*P<0.05),修正前后比值达到40~50倍。结论 EMG修正对振幅标准化有重要意义,其中对c VEMP的测试结果影响较大,建立一组EMG修正后VEMPs的正常参考值范围能够更准确评估双侧不对称性。Tone-burst c VEMP及o VEMP引出率高,可作为临床上评估椭圆囊和球囊功能的常规检测方法。     

三种眼位眼性前庭诱发肌源性电位的临床研究

目的分析三种眼位状态下眼性前庭诱发肌源性电位(ocular vestibular evoked myogenic potential,oVEMP)的波形特征,探讨oVEMP检测的适宜眼位。方法研究对象为2017年12月至2018年5月行oVEMP检查的15例(30耳)眩晕患者(患者组),其中男7例、女8例,平均年龄(51±13)岁;另外选择22名(44耳)健康青年人作为对照组,其中男10名、女12名,平均年龄(23±5)岁。全部受试者分别采取正中向上30°凝视(中上位)、右上45°凝视(右上位)以及左上45°凝视(左上位)三种眼位进行oVEMP检测,分别记录三种眼位oVEMP的引出率、N1潜伏期、P1潜伏期、N1-P1间期、N1-P1幅值以及耳间幅值不对称比,采用SPSS 23.0统计软件进行分析比较。结果对照组内、患者组内以及总体受试者三种眼位oVEMP的引出率差异均无统计学意义(P值均>0.05);N1潜伏期、P1潜伏期、N1-P1间期、N1-P1幅值、耳间幅值不对称比的差异亦均无统计学意义(P值均>0.05)。结论中上位、右上位以及左上位均可作为临床oVEMP检测的眼位,其引出率和波形特征不存在差别,当其中一种眼位凝视困难或不容易得到重合曲线时,可以采用另外两种眼位进行检测。     

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.     

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。     

突聋伴眩晕患者前庭诱发肌源性电位的临床研究

目的通过观察突发性聋伴眩晕患者前庭诱发肌源性电位的引出率及各参数,探讨前庭诱发肌源性电位对突聋伴眩晕患者内耳损伤情况的诊断及预后评估。方法收集50例单耳突聋伴眩晕的患者,50例单耳突聋不伴眩晕患者及60例正常听力人作为对照组,分析对比o VEMP及c VEMP的引出率和各参数变化。结果引出率:病例组患耳、对侧耳、突聋不伴眩晕组及正常对照组o VEMP引出率分别为24%、42%、48%、100%,c VEMP引出率分别为:56%、74%、64%、100%,病例组患耳和对侧耳相比,o VEMP及c VEMP引出率差异无统计学意义(P>0.05),病例组患耳及对侧耳分别和正常对照组比较,o VEMP及c VEMP引出率均明显降低(P<0.05),病例组患耳o VEMP引出率明显低于突聋不伴眩晕组(P<0.05)。o VEMP:病例组患耳、对侧耳、突聋不伴眩晕组及正常对照组的各参数(N1潜伏期、P1潜伏期、P1-N1振幅)两两比较,组间不对称比(AR)比较,差异均无统计学意义(P均>0.05)。c VEMP:病例组患耳、对侧耳、突聋不伴眩晕组及正常对照组的各参数比较,患耳及对侧耳P1-N1振幅比突聋不伴眩晕组及正常对照组均明显降低(P<0.05),病例组AR比正常对照组明显增高(P<0.05),o VEMP及c VEMP结果与听力损失分型、听力损失程度分级无明显相关性(P>0.05),但与疗效分级明显相关(P<0.05)。结论突聋伴眩晕患者存在同侧及对侧的椭圆囊(前庭上神经)和球囊(前庭下神经)传导功能障碍,前庭诱发肌源性电位为突聋伴眩晕患者耳石器及前庭神经功能评估提供客观依据。     

Vestibular evoked myogenic potential (VEMP) results in migraine and migrainous vertigo

Abstract

Background: The pathophysiology of vertigo is not fully known; thus, it is difficult to diagnose vestibular migraine (VM) in some migraine patients with vertigo symptoms.

Aims/objectives: We aimed to evaluate the diagnostic value of cervical vestibular evoked myogenic potential (cVEMP) in patients with VM.

Materials and Methods: Thirty-two patients diagnosed with migraine and 31 patients with VM were prospectively included in this study. The cVEMP responses were obtained, and P1-N1 latency, interpeak amplitude, amplitude asymmetry ratio were calculated. The patients' demographics, results of physical and audiometric examinations, and VEMP records as well as absence of responses were evaluated and compared between groups.

Results: The incidence of ears with absence VEMP responses was found to be numerically higher in the migraine group than in the VM group (p?=?.106). Additionally, there were no statistically significant differences detected between the groups in terms of the p13 or n23 latency, interpeak amplitude, and amplitude asymmetry ratio measured in both right and left ears (p?>?.05).

Conclusions: The increased rate of absent VEMPs was associated with the hypoperfusion of the sacculo-collic reflex pathway in migraine patients. In addition, it was concluded that VEMP reflex responses appear to be insufficient to differentiate between VM and migraine diagnoses.     

Variance of vestibular-evoked myogenic potentials

OBJECTIVES/HYPOTHESIS: Vestibular-evoked myogenic potential (VEMP) has been thought to originate from sacculus. The variance of this potential and the effectiveness of the adjustments of pInII amplitudes using average muscle tonus of ipsilateral sternocleidomastoid muscle were evaluated. In addition, clinical application of VEMP was examined in patients with acoustic tumors (ATs) and vestibular neurolabyrinthitis (VNL). STUDY DESIGN: Prospective evaluation of the VEMP in 18 normal volunteers and 6 patients. METHODS: Variance and left-right difference of each parameter, including pI latency, nII latency, pInII amplitude, and threshold, was analyzed. Input-output function of pInII amplitude was evaluated. Average muscle tonus was calculated in 20 ears and applied for adjustment of pInII amplitude. Sensitivity of each parameter of VEMP was examined in 3 patients with ATs and 3 patients with VNL. RESULTS: VEMP was present in all 36 ears of 18 control subjects. Thresholds of VEMP for normal subjects were 80 to 95 dB normal hearing level (nHL). The muscle tonus affected pInII amplitude significantly; however, no statistically significant improvement was observed in test-retest investigation after adjustment using muscle tonus. The threshold of the affected side was elevated compared with the non-affected side in all patients with ATs, whereas 2 of 3 patients showed normal pInII-ratio. One patient with VNL presented normal VEMP, whereas 2 patients presented no VEMP to the highest stimulus intensity. CONCLUSIONS: Interaural difference of thresholds might be the most useful parameters. Adjustment using average muscle tonus is not necessary when the subject is able to get sufficient muscle tonus.     

The effect of saccular function on static balance ability of profound hearing-impaired children

Objective

Researches have shown that in clinical practice, balance disorders in children with congenital or early acquired severe to profound hearing loss are probable. The purposes of present study were to specify the percentage of vestibular evoked myogenic potential (VEMP) and an acoustically evoked, short latency negative response (ASNR) recordings and the relation between their presence and static balance ability and postural control of children with profound sensorineural hearing loss (SNHL).

Methods

Thirty children with profound SNHL, with an average age of 6.93 years, underwent the VEMP and auditory brainstem response (ABR) tests. Both VEMP and ABR were recorded at the threshold level through air-conduction stimulation via an insert receiver. The static balance performance of the hearing-impaired children was tested with six exercises and compared with that of 30 age- and sex-matched normal-hearing children as controls.

Results

VEMP was recorded in 53.3% of ears and ASNR in 40.0%. VEMP was revealed in all ears with ASNR, and a significant correlation was shown between their presence (p = 0.005) and also between the ASNR wave latency and P1 (p = 0.0001) and N1 (p = 0.004) wave amplitude of VEMP. There was a significant correlation between the presence of VEMP and ASNR with the performance of the children in two static balance skills, namely standing on one leg with eyes open on a line and the same practice on the balance beam (p ≤ 0.008).

Conclusion

There was a close relation between the presence of VEMP and ASNR. Additionally, when ASNR was present, the recording of VEMP could be expected. Successful performance in the static balance exercises with reduced vestibular and somatosensory inputs increased the possibility of the recording of ASNR and VEMP.     

人类声诱发短潜伏期负电位的研究

目的在极重度感音性聋耳的ABR检测中发现一个位于3～4ms潜伏期的"V"字形负向波形,称声诱发短潜伏期负电位(Acoustically Evoked Short Latency Negative Response,ASNR)。本研究通过大宗病例调查和临床实验来探讨ASNR的特点和起源。方法回顾性调查并分析3104例ABR检测结果,以详尽了解ASNR的出现率和特性。对20名双耳极重度感音性耳聋患者(6～62岁)和12名健康人(23～30岁)进行了ABR和前庭诱发肌源性电位(VEMP)测试。患者组包括了16名人工耳蜗植入术后的患者,植入耳在裸耳状态时可提供无功能耳蜗模型。结果判读侧重于:人工耳蜗植入耳能否诱发ASNR,以及对比在极重度感音性聋耳中ASNR组和非ASNR组的VEMP出现率及反应阈值。结果ASNR仅出现于极重度感音性聋耳,并且对强声刺激(80～120dBnHL)有依赖性。在653例极重度感音性聋患者(981耳)的ABR波形中,有80例(12.3%)117耳(11.9%)出现了ASNR。ASNR有良好的重复性,可排除伪迹干扰的可能性。ASNR具有神经电位的特征,表现在随着声刺激的增强,其潜伏期缩短而振幅增大。ASNR与ABR的波形完全不一样,无法将其解释为传统听觉神经通路产生的电位。临床实验中,3个人工耳蜗植入耳能诱发出ASNR,说明ASNR的发生与耳蜗无关。所有9个ASNR耳都诱发出VEMP,且阈值与正常对照组无统计学差异(P>0.05),提示ASNR耳具有正常的球囊功能。在非ASNR组中,三分之二没有引出VEMP,而另外三分之一虽然可以诱发出VEMP,但阈值明显较正常对照组高(P<0.01),分别提示球囊功能丧失或低下。此外,有一外半规管麻痹耳诱发出了ASNR和VEMP。结论ASNR并非伪迹,而是一种依赖强声刺激,且只出现于极重度感音性聋耳的神经电位。ASNR的出现完全依赖于正常的球囊功能,而不依赖于残余听力或者半规管功能。据此认为ASNR起源感觉器官为球囊,根据其潜伏期推测电位源自前庭神经核。     

Vestibular evoked myogenic potentials in young children: test parameters and normative data

OBJECTIVE: The vestibular evoked myogenic potential (VEMP) is a test of the vestibulocollic reflex that has been extensively studied in adults. Much is known about the normal values in adults as well as their changes with age. In children, the expected test values and their possible changes in development have not yet been described nor has the feasibility of reliable testing in this group. The aim of this prospective study is to accumulate normative data and to verify the viability of testing in young children. The study focused on optimal test parameters, reproducibility, and subject compliance in a pediatric population. METHODS: Thirty normal-hearing children (60 ears) ages 3 to 11 completed VEMP testing and audiograms for analysis. VEMP testing was performed with alternating clicks at three intensities (80-, 85-, and 90-dB normalized hearing level) using averaged, unrectified electromyograms recorded by surface electrode on the sternocleidomastoid muscle ipsilateral to the stimulus. VEMP latencies, amplitude, compliance, and length of testing were recorded for each patient, as well as their feedback on the testing session. The subjects were divided into four age groups for analysis. RESULTS: All but one of the subjects attempting VEMP testing was able to finish. Of 30 children completing VEMP tests, bilateral reflexes were recorded for all subjects with symmetric responses in 28 of 30 subjects (93%). The mean peak latencies (+/- standard deviation [SD]) of pI and nII were 11.3 msec (1.3 ms) and 17.6 msec (1.4 ms), respectively. The mean pI-nII amplitude (+/- SD) was 122 muV (68 muV). There was a significantly shorter nII mean peak latency of group I (ages 3-5) left ear in comparison to other groups, with an absolute shorter mean latency nII in the right ear of group I (not significant). Average test time was 15 minutes with two researchers testing, and subjects were highly compliant. CONCLUSIONS: VEMP is a well-tolerated test for screening vestibular function in young children, performed with minimal test time and reproducible results. Mean latencies in this study suggested a shorter initial negative peak (nII) than in adult studies, consistent with prolongation seen in previous research on the effects of age. Ninety-decibel normalized hearing level clicks were adequate for uniform response rates. Expected latency and amplitude values in single-channel VEMP-unrectified electromyograms were established. This is the first study describing expected latencies and optimal testing parameters in children.     

Vestibular evoked myogenic potentials in delayed endolymphatic hydrops

OBJECTIVE/HYPOTHESIS: Vestibular evoked myogenic potential (VEMP) has become an established test to explore the sacculo-collic reflex. The study aims to investigate the VEMPs in cases of delayed endolymphatic hydrops because greatly dilated saccule was observed in histopathological specimens of delayed endolymphatic hydrops. STUDY DESIGN: Prospective study. METHODS: Twenty patients with delayed endolymphatic hydrops were subjected to pure-tone audiometry, caloric testing, and VEMP test. Delayed VEMP was defined as the latency of peak I exceeding 22.6 milliseconds or of peak II exceeding 33.1 milliseconds. Interaural amplitude difference over the sum of amplitudes of both ears was measured, and when the ratio exceeded 0.36, it was identified as augmented VEMP or depressed VEMP depending on whether the amplitude of the lesioned side was greater or less than the opposite side. RESULTS: The VEMP test revealed that 9 patients (45%) were normal, 6 (30%) exhibited absent VEMPs, and 5 (25%) displayed abnormal VEMPs, including delayed VEMPs in 2, depressed VEMPs in 2, and augmented VEMPs in 1. The caloric test indicated that 9 (47%) of the 19 ears exhibited normal caloric response, whereas 10 ears displayed abnormal caloric responses including canal paresis in 8 and absent caloric response in 2. Six ears had preserved both the caloric response and the VEMPs, whereas no ear demonstrated both absent caloric response and absent VEMPs. CONCLUSIONS: The residual caloric as well as saccular functions after ear insult may determine whether delayed endolymphatic hydrops will occur. These findings suggest that patients with sudden deafness or juvenile unilateral total deafness should undergo caloric testing and VEMP test to predict the occurrence of delayed endolymphatic hydrops in the future.