声刺激诱发麻醉豚鼠前庭咬肌反射及起源的研究

目的 建立声诱发前庭咬肌反射的动物模型,探讨咬肌反射电位的特征及起源.方法 20只豚鼠,随机分为正常对照组(10只)、单侧前庭下神经切断组(5只)、单侧耳蜗神经破坏组(5只).3组动物分别在麻醉下于豚鼠下颌骨及颅顶之间用金属夹夹住,使咬肌保持一定的张力,记录click声诱发的咬肌反射电位,并进行听性脑干反应(ABR)测试.结果正常对照组豚鼠声诱发咬肌反射电位的负波(negative peak,NP)阈值为92±7.68dB nHL.给予100、90、80、70 dB nHL单侧声刺激时,同侧记录咬肌反射NP引出率分别为100%、7O%、40%、0%.给予100、90、80 dB nHL单侧声刺激时,同侧记录咬肌反射NP平均潜伏期分别为6.57±0.26、6.64±0.23、6.69±0.19 ms,不同刺激强度下NP潜伏期差异无统计学意义(P>0.05).ABR的平均反应阈为31±7.88 dBnHL.单侧前庭下神经切断组术侧声诱发咬肌反射消失,ABR反应阈在正常范围内.单侧耳蜗神经破坏组术侧声诱发咬肌反射存在,NP阈值及潜伏期与正常对照组差异无统计学意义(P>0.05),ABR消失.结论 在豚鼠下颌骨及颅顶之间应用金属夹使咬肌保持一定的张力,同时给予click声刺激,可以建立一个理想的声刺激诱发前庭咬肌反射的动物模型;声刺激诱发的豚鼠咬肌反射电位NP来源于前庭,且该反射是肌源性的.     

声刺激诱发的豚鼠咬肌肌源性电位是负波吗?

本刊2010年第18卷第3期刊登了由华中科技大学同济医学院附属协和医院耳鼻咽喉-头颈外科孙伟、孔维佳、范国润撰写的题为《声刺激诱发麻醉豚鼠前庭咬肌反射及起源的研究》论著,阅读该文后,空军航空医学研究所的谢溯江、徐珀、贾宏博给编辑部发来了"读者来信",希望就文中的某些学术问题与作者或同道们进行探讨,以利于进一步促进声诱发咬肌反射的研究。现将谢溯江等的"读者来信"及孙伟等的回函全文刊出,欢迎广大同道们阅读,并可致函编辑部参与讨论。同时,也欢迎并希望广大同道今后继续以类似的形式展开学术讨论。     

小型猪肌源性诱发前庭电位的检测

目的探索小型猪肌源性诱发前庭电位(Vestibular-evoked myogenic potential,VEMP)的最佳检测方法。方法选取正常成年的雌性小型巴马香猪,以3%戊巴比妥钠+速眠新Ⅱ进行麻醉之后,用自制装置进行固定,1000Hz强短声诱发颈部伸肌肌源性电位和咬肌肌源性电位,并记录其波形;结果颈部伸肌诱发肌源性电位,第一个正向波P的潜伏期7.65±0.64ms,振幅1.66±0.34uv,80dBSPL的引出率为75%;咬肌诱发肌源性电位,第一个正向波P的潜伏期7.60±0.78ms,振幅1.31±0.28uv,80dBSPL的引出率为66%。结论小型猪颈部伸肌和咬肌在强声下诱发的肌源性电位潜伏期和阈值均一致;颈部伸肌部位所记录到的VEMF波幅稍高于咬肌部位记录到波幅;但相比之下,咬肌位置表浅,便于定位,肌肉组织发达,肌紧张性强,更易于肌源性诱发电位的记录。     

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。     

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。     

前庭诱发肌源性电位临床应用的研究现状

前庭诱发肌源性电位(Vestibular Evoked Myogenic Potentials,VEMPs)是通过刺激微纹区的Ⅰ型毛细胞所产生的一种肌源性反应,主要反映球囊、椭圆囊的功能及前庭颈、前庭眼反射通路的完整性。VEMPs目前主要应用于前庭、中枢相关疾病的诊断及鉴别诊断,本文将就其信号产生、参数正常值及临床应用的研究进展进行综述。     

下颌气囊压力反馈装置应用于前庭诱发肌源性电位检测

目的介绍一种监测和控制胸锁乳突肌收缩力度的下颌气囊压力反馈装置,以提高前庭诱发肌源性电位(vestibular evoked myogenic potential,VEMP)检测结果的可重复性和可靠性。方法研究对象为19名健康志愿者,12名男性,平均年龄34.0±7.7岁;7名女性,平均年龄29.8±2.9岁;对受试者进行VEMP检测,测试时应用下颌气囊压力反馈装置。受检者取坐位,将下颌置于连接压力计的气囊上,以颈部肌肉牵引下颌压迫气囊,维持压力在120mmHg。记录胸锁乳突肌电位P13和N23反应时间、P13-N23峰值差。对其中9名志愿者连续三周每周检测一次,以检验其可重复性。结果 19例受试者P13和N23反应时间分别为13.97±1.33和24.03±1.79ms,P13-N23峰值差平均为66.89±44.1μV。左右耳之间各项指标差异均无统计学意义。9例重复检测者的结果具有良好的可重复性,P13和N23反应时间组内相关系数分别为0.8和0.93,P13-N23峰值差组内相关系数为0.97。结论行VEMP检测时应用下颌气囊压力反馈装置简单易行,受检者在检测过程中可以维持胸锁乳突肌收缩力度,提高检测结果的可重复性和可靠性。     

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。     

前庭诱发肌源性电位对前庭下神经炎的诊断价值

目的　探讨前庭诱发肌源性电位（VEMP）对前庭下神经炎的诊断价值。方法　回顾分析我科眩晕门诊18例前庭下神经炎的临床资料,尤其是VEMP检测结果。结果　18例患者中,15例表现为旋转性眩晕,3例为平衡障碍,所有患者纯音测听、冷热试验及眼性前庭诱发肌源性电位（oVEMP）正常而颈性前庭诱发肌源性电位（cVEMP）异常。其中14例cVEMP检查不能引出,4例振幅低下。3个月后复诊10例患者症状消失,复查cVEMP 9例恢复正常,1例振幅低下;半年复诊18例患者症状全部消失,复查cVEMP只有2例振幅低下,其余均恢复正常。结论　VEMP检查对前庭下神经炎的精准诊断及判断预后有重要临床价值,值得临床推广。     

不同种类刺激声对国人正常青年人群眼肌前庭诱发肌源性电位的影响

目的：观察不同种类刺激声对中国正常青年人群气导声刺激诱发的眼肌前庭诱发肌源性电位（ACS-oVEMP）的影响。方法：选择22例正常人为研究对象,分别采用500Hz tone brust、125Hz tone burst和Click作为诱发刺激声进行双耳（44耳）ACS-oVEMP检测,观察和比较ACS-oVEMP波形的引出率、阈值、nⅠ潜伏期、pⅠ潜伏期、nⅠ-pⅠ波间期、振幅及耳间对称性情况。结果：500Hz tone burst诱发的ACS-oVEMP引出率为100%（44/44）,125Hz tone burst的引出率为40.9%（18/44）,Click的引出率为29.6%（12/44）。500Hz tone burst与其他2组间引出率比较差异有统计学意义（P〈0.05）;500Hz tone burst的振幅最大[（7.3±5.5）μV],与125Hz tone burst[（3.8±1.5）μV]和Click[（5.8±1.3）μV]2组间振幅比较差异有统计学意义（P〈0.05）;其他波形参数比较亦差异有统计学意义。结论：不同刺激声可以对ACS-oVEMP的波形造成影响,500Hz tone burst诱发的ACS-oVEMP引出率最高,振幅最大,波形最易辨认。     

Influence of gender on the vestibular evoked myogenic potential

There is no consensus on the relevance of factors that influence gender differences in the behavior of muscles. Some studies have reported a relationship between muscle tension and amplitude of the vestibular evoked myogenic potential; others, that results depend on which muscles are studied or on how much load is applied.AimsThis study aims to compare vestibular evoked myogenic potential parameters between genders in young individuals.MethodsEighty young adults were selected - 40 men and 40 women. Stimuli were averaged tonebursts at 500 Hz, 90 dBHL intensity, and a 10-1000 Hz bandpass filter with amplification of 10-25 microvolts per division. The recordings were made in 80 ms windows.Study typeAn experimental and prospective study.ResultsNo significant gender differences were found in wave latency - p = 0.19 and p = 0.50 for waves P13 and N23, respectively. No differences were found in amplitude values - p = 0.28 p = 0.40 for waves P13 and N23, respectively.ConclusionThere were no gender differences in latency and amplitude factors; the sternocleidomastoid muscle strain was monitored during the examination.     

Short-latency EMG potentials elicited by head taps in sternocleidomastoid muscles: a study on normal human subjects and patients with central or vestibular lesions

The aim of the present study was to determine whether a tap on the forehead evokes a vestibulospinal reflex in sternocleidomastoid muscles in normal human subjects and patients with central or vestibular lesions. While first positive–negative short-latency EMG potentials with a mean positive potential peak of about 12 ms and a mean negative potential peak of about 17 ms were found in the bilateral sternocleidomastoid muscles in normal subjects, they disappeared or were attenuated in patients with central or peripheral vestibular lesions.     

A study on vestibular-evoked myogenic potentials via galvanic vestibular stimulation in normal people

Objectives

The aim of our study is to examine vestibular-evoked myogenic potentials (VEMPs) elicited by the galvanic vestibular stimulation in the sternocleidomastoid muscle (SCM) in healthy subjects for clinical applications of auditory neuropathy or vestibular neuropathy in the future.

Effects of cochlear implants on otolith function as evaluated by vestibulo-ocular reflex and vestibular evoked myogenic potentials

ObjectiveThe aim of this study was to investigate whether the insertion of an implant into the cochlea is accompanied by a deterioration in otolith function. Cervical and ocular vestibular evoked myogenic potentials (cVEMP and oVEMP) and linear vestibulo-ocular reflex (lVOR) during eccentric rotation were assessed before and after cochlear implantation (CI) to evaluate otolith function.MethodsTwelve patients with bilateral severe sensorineural hearing loss who had undergone CI surgery in our hospital between May 2016 and November 2017 were included in this study. cVEMP and oVEMP were assessed using the asymmetry ratio (AR), calculated with the following formula: [(peak-to-peak amplitude calculated as the sum of the p13 and n23 amplitudes in the non-operated side) − (that in the operated side)]/[(that in the non-operated side) + (that in the operated side)]. The ratio of VOR gain during eccentric rotation against VOR gain during center rotation was used to assess lVOR. For eccentric rotation, patients were rotated while displaced from the axis of rotation. At the same time, linear acceleration stimulated the utricle and induced lVOR. All patients underwent cVEMP and oVEMP tests and center and eccentric rotation tests before and about 30 days after CI surgery.ResultsThree patients with absent cVEMP responses before surgery were excluded, leaving pre-surgery cVEMP results for 9/12 patients. In five of these patients, the AR of cVEMP increased after CI, indicating that saccular function, as evaluated by cVEMP, did not deteriorate significantly postoperatively. One patient with an absent oVEMP response before CI was excluded, leaving pre-surgery oVEMP results for 11/12 patients. In 10 of these patients, the AR of oVEMP increased after CI surgery, indicating that utricular function, as evaluated by oVEMP, deteriorated significantly postoperatively. However, because the ratio of VOR gain during eccentric rotation against VOR gain during center rotation did not become worse after CI, utricular function, as evaluated by lVOR, did not deteriorate significantly postoperatively. Symptoms of vertigo became worse after CI in two of the 12 patients.ConclusionCI does not cause a deterioration in saccular function, as evaluated by cVEMP. Although CI does cause a deterioration in utricular function in oVEMP tests, this is not consistent in lVOR tests. These results indicate that CI causes a slight deterioration in utricular function that is insufficient to cause vertigo or deterioration of lVOR.     

The effect of EMG magnitude on the masseter vestibular evoked myogenic potential (mVEMP)

IntroductionThe masseter vestibular evoked myogenic potential (mVEMP) is a bilaterally generated, electromyographically (EMG)-mediated response innervated by the trigeminal nerve. The purpose of the present investigation was to 1) determine whether subjects could accurately achieve and maintain a range of EMG target levels, 2) to examine the effects of varied EMG levels on the latencies and amplitudes of the mVEMP, and 3) to investigate the degree of side-to-side asymmetry and any effects of EMG activation.MethodsSubjects were nine neurologically and otologically normal young adults. A high-intensity tone burst was presented monaurally while subjects were seated upright and asked to match a range of EMG target levels by clenching their teeth. Recordings were made from the ipsilateral and contralateral masseter muscles referenced to the ear being monaurally stimulated.ResultsWe found that the tonic EMG target had no effect on mVEMP latency. Additionally, although mVEMP amplitudes “scaled” to the EMG target, there was a tendency for the subjects’ EMG level to “undershoot” the EMG target levels greater than 50 μV. While some individuals did generate differences in EMG activation between sides, there were no significant differences on average EMG activation between sides. Further, while average corrected amplitude asymmetry was similar across EMG targets, some individuals demonstrated large, corrected amplitude asymmetry ratios.ConclusionsThe results of this investigation suggest that, as with cVEMP recordings, the underlying EMG activation may vary between subjects and could impact mVEMP amplitudes, yet could be mitigated by amplitude correction techniques. Further it is important to be aware that even young normal subjects have difficulty maintaining large, tonic EMG activity during the mVEMP recording.     

Properties of binaural vestibular evoked myogenic potentials elicited with air-conducted and bone-conducted tone bursts

The purpose of this investigation was to compare the effects of monaural and binaural stimulation on unilaterally-measured vestibular evoked myogenic potential (VEMP) magnitude and latency. The subjects were eighteen normal-hearing adults with no history of vestibular disease. Monaural VEMPs were acquired with air-conducted (AC) and bone-conducted (BC) 500 Hz tone bursts presented at 95 dB nHL and 70 dB nHL, respectively. These stimuli were simultaneously paired with 95 dB nHL contralateral tone bursts at 250, 500, 750, or 1000 Hz during acquisition of binaural VEMPs. Results indicated that AC-VEMP relative magnitudes decreased in each of the binaural conditions compared to the monaural condition. However, no changes in relative magnitude between conditions occurred for BC-VEMPs. Similar latencies were observed for monaural and binaural VEMPs. Differences in bilateral interaction seen between the AC-VEMP and BC-VEMP conditions are consistent with modification of sound transmission through the ear during presentations of binaural sound.     

Effect of head position on vestibular evoked myogenic potentials with toneburst stimuli

Conclusion. The present study demonstrated the robustness of VEMP testing with toneburst stimuli, since it is hardly affected by head position, i.e. base or tonic excitation levels of the saccule and inferior vestibular nerve. However, the small but highly significant difference found in latency should not be neglected: the gravitational axis in the upright position may have some special effect on tonic excitation of the saccule. Objectives. To evaluate the effect of head positions on vestibular evoked myogenic potentials (VEMPs) with toneburst stimuli. Materials and methods. VEMPs were recorded with short tonebursts of 500 Hz in 14 normal subjects in 5 head positions (upright, nose up, ear up, nose down, and ear down). The three parameters analyzed were: 1) latency of p13, 2) latency of n23, and 3) corrected amplitude of p13-n23 (CA p13-n23). Results. One-way repeated measures ANOVA showed significant effects on both p13 (p=0.0245) and n23 (p<0.0001) latencies, but not on CA p13-n23. Bonferroni's post hoc test demonstrated that there were significant differences in n23 latency between the upright position and all other head positions leaning on the bed.     

Effect of stylet removal on neural response telemetry and stapedial reflex thresholds during cochlear implantation

Objective

The purpose of this study was to analyze changes in neural response telemetry (NRT) and electrically evoked stapedial reflex thresholds (ESRT) before and after stylet withdrawal during cochlear implant surgery.

Methods

Thirty children (21–92 months old) who were candidates for cochlear implantation took part in this study. In all of them Nucleus Contour Advance was implanted. NRT and ESRT responses were recorded initially with the stylet in and then when the stylet was taken out during the implant procedure. The recordings were performed in the basal, middle, and apical areas of the electrode array.

Results

The threshold levels required to obtain NRT and ESRT responses after stylet removal were lower. This decrease was observed in all parts of the cochlea. It was statistically significant in all areas with the exception of the basal ESRT measurements.

Conclusion

Withdrawing the stylet results in better NRT and ESRT responses, most probably due to a favorable position change of the electrode array within the scala tympani.     

Influence of nerve branch of origin and extracanalicular extension of the tumor on hearing after middle fossa removal of vestibular schwannoma

Conclusion. Neither nerve branch of origin nor extracanalicular (up to 1 cm) extension of a vestibular schwannoma (VS) influence the postoperative hearing outcome in patients operated via a middle cranial fossa (MCF) approach. Objective. To test whether the nerve branch of tumor origin and an extracanalicular, up to 1 cm, tumor extension influences hearing outcome after MCF VS surgery. Patients and methods. This was a retrospective case review of 50 patients with postoperative pure-tone audiogram (PTA) performed later than 90 days after surgery. Twenty patients had a superior vestibular nerve (SVN) tumor and 27 patients had an inferior vestibular nerve (IVN) tumor. In three patients the nerve branch of origin of the VS could not be unequivocally determined. Thirty-four patients had a purely intracanalicular (IC) tumor and 16 patients had an extracanalicular extension in the cerebello-pontine angle. The differences between preoperative and postoperative air-conduction pure-tone hearing thresholds at 500, 1000, 2000, 3000, and 4000 Hz were compared between groups using the Mann–Whitney–Wilcoxon test. Results. Neither vestibular nerve branch of origin nor extracanalicular tumor extension (up to 1 cm) caused any significant difference in the degree of postoperative hearing change at any of the tested PTA frequencies.