Electrocochleography in the Diagnosis of Meniere's Disease

This study prospectively analyses electrocochleography (ECoG) recordings obtained from ears demonstrating symptoms highly suggestive of Meniere's disease. Comparison is made with ECoG recording from ears in which the diagnosis of Meniere's is considered unlikely (control ears). Electrocochleograph recordings were made through a transtympanic recording needle, situated in the round window niche. Analysis was made of the 1 kHz tone burst summation potential (SP) and the summation potential : action potential (SP/AP) ratio response to a 90 dB click. All patients were prospectively awarded a Meniere's score based on a 10-point scale, and comparison was made between ears awarded a score of 7 or greater (Meniere's ears;n>500), and ears awarded a score 3 or less (control ears; n>900). Results demonstrate a significant difference in the 1 kHz SP response, and the SP/AP ratio, between ?control? and ?Meniere's? ears. Furthermore, we show that SP negativity is proportional to the amplitude of the AP click response, and in patients producing an AP click amplitude exceeding 10 V, sensitivity of the tone burst test approaches 85%. This study provides further evidence suggesting the useful role of electrocochleography in determining a diagnosis of endolymphatic hydrops, and demonstrates improved sensitivity of the 1 kHz SP response, compared with SP/AP click ratio, in the diagnosis of Meniere's disease.     

Sensitivity and Specificity of Transtympanic Electrocochleography in Meniere's Disease

Transtympanic electrocochleography (TT ECoG) was conducted in 61 patients (61 ears) with the clinical diagnosis of Meniere's disease and 15 patients (21 ears) with cochlear hearing loss of other aetiologies to assess the ability of the method to separate different cochlear disorders. The click-evoked summation potential/action potential (SP/AP) ratio and the 1 and 2 kHz burst-evoked SP amplitudes were evaluated. Based on the TT ECoG results from 13 normal hearing subjects (15 ears) the upper limit of each variable was determined, above which a value was considered pathological, i.e. indicative of endolymphatic hydrops. The results showed that the sensitivity of the SP/AP ratio was 62% and specificity 95%. When evaluating the combinations of TT ECoG parameters with logistic regression, SP/AP ratio and 1 kHz burst-evoked SP amplitude were shown to increase the discriminating ability of TT ECoG significantly. Inclusion of the 1 kHz burst-evoked SP amplitudes increased sensitivity to 82%, without changing specificity. Inclusion of the 2 kHz burst had no effect on sensitivity or specificity.     

Meniere's disease: the incidence of hydrops in the contralateral asymptomatic ear

OBJECTIVE: This study analyzes the incidence of endolymphatic hydrops in the asymptomatic contralateral ear of patients with classic Meniere's disease. STUDY DESIGN: A retrospective study of 3000 subjects who underwent electrocochleography (ECOG) from 1988 to 1998. METHODS: The presence of endolymphatic hydrops was determined by use of ECOG recordings, which were made through a transtympanic recording needle situated in the round window niche. Analysis was made of the 1-kHz toneburst summation potential (SP), and comparison was made between asymptomatic contralateral "Meniere's ears" (n = 144) and asymptomatic normal "control ears" (n = 114). RESULTS: Results demonstrated that more than 10% of the contralateral asymptomatic Meniere's ears have an ECOG recording that is highly suggestive of the presence of endolymphatic hydrops. In contrast, less than 2% of the control population demonstrate abnormal ECOG recordings. Furthermore, 15% of the population of contralateral Meniere's ears lie above the 95th percentile of the control population for 1-kHz tone-burst (100 dB) SP negativity. CONCLUSIONS: This study suggests that a high percentage of patients who have what appears to be unilateral Meniere's disease have evidence of endolymphatic hydrops in the contralateral asymptomatic ear. This finding has important clinical relevance for the management of patients in whom destructive surgery is planned and further highlights the importance of electrocochleography in the diagnosis and management of this disease process.     

Comparison of summating potential in Menière's disease between trans- and extratympanic electrocochleography

The summating potential (SP) recorded concurrently with transtympanic (TT) and extratympanic (ET) electrocochleography in Menière ears was compared with respect to polarity and amplitude. There was a difference in SP polarity and amplitude between the two methods. The incidence of the increase in the ratio of -SP amplitude to the amplitude of the auditory nerve action potential (AP) (-SP/AP ratio) at 80 dB nHL as a response to a click was higher with the ET than with the TT method. Most of the ears exhibiting an increased +SP/AP ratio with the TT method showed an increased -SP/AP ratio with the ET method. The incidence of increased SP/AP ratios including -SP/AP and +SP/AP ratios was similar with both methods. A +SP was recorded in 14 of 25 ears upon stimulation with an 8-kHz tone burst with the TT method, whereas no +SP was recorded in 25 ears with the ET method. Tone bursts of 1 and 2 kHz produced a -SP and similar waveforms with both methods. Comparison of -SP amplitude recorded with both methods revealed that the ratio of -SP amplitude with both methods is different across the stimulus frequencies. The present study suggests that the -SP elicited by tone bursts of mid to low frequencies is more stable in the diagnosis of Menière's disease than -SP elicited by a click because of the lesser influence of the electrode location and that the increase in the +SP recorded with the TT method may be of clinical significance in the diagnosis of Menière's disease.     

Extratympanic electrocochleography: diagnostic and predictive value

OBJECTIVE: To define the clinical value of extratympanic electrocochleography (ECoG) in the diagnosis of Meniere's disease. STUDY DESIGN: Retrospective case review. SETTING: An otology/neurotology referral center. PATIENTS: A group of 252 patients with symptoms consistent with Meniere's disease and 20 normal-hearing control subjects. INTERVENTION: All patients underwent audiologic testing and extratympanic ECoG at the time of initial evaluation and, when possible, following treatment. MAIN OUTCOME MEASURES: Audiologic thresholds and summating and action potential ratios (SP:AP). RESULTS: Patients were classified into definite, probable, possible, and bilateral Meniere's disease groups according to American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) guidelines. The definite Meniere's group demonstrated an elevated SP:AP ratio in 74% of cases, the possible Meniere's group in 64%, and the bilateral group demonstrated elevated ratios in both ears in 66%. Contralateral ears produced elevated ratios in 42% for unilateral cases, whereas 40% of these ears reported at least one contralateral symptom. All 40 control ears were normal (SP:AP > or = 0.50). Results statistically correlated (p = 0.004) with the Meniere's staging system set forth in the 1995 AAO-HNS guidelines. No correlation was found between ECoG results and disease duration. Although 72% of the 86 follow-up patients reported complete or substantial vertigo control, changes from initial ECoG results did not specifically correlate to vertigo, tinnitus, or aural fullness improvement. CONCLUSIONS: Extratympanic ECoG can be useful in the diagnosis of Meniere's disease, lending promise to possible cases where objective audiologic data are lacking. Each testing center should study its own results to establish meaningful parameters and confidence levels.     

Clinical significance of the summating potential in Menière's disease

Transtympanic (TT) electrocochleography (ECochG) data recorded with click stimuli and tone bursts (1, 2, 4, and 8 kHz) were evaluated in 50 patients with Meniere's disease and compared with the data from control groups of 10 sensorineural hearing impaired patients and 5 subjects with normal hearing. The mean summating potential (SP) amplitude was larger in the Meniere's disease group for 1, 2, and 8 kHz. The low frequency (1 or 2 kHz) SP decreased in 59% of the Meniere's disease patients during a glycerol dehydration test, whereas subjective hearing improved in only 29%. The use of ECochG with the monitoring of SP thus improves the sensitivity of the glycerol test for the detection of endolymphatic hydrops. There appeared no clear relation between clinical observations and the ECochG data either before or after glycerol. However, the Meniere's disease patients with a large negative SP at low frequencies also had larger action potential (AP) and often had short-term symptoms. The present report confirms the usefulness of measuring the SP in the diagnosis of Meniere's disease.     

鼓膜电极检测有频率特性的—SP／AP

用短声（Ｃｌｉｃｋ）和短纯音（ｔｏｎｅｂｕｒｓｔ）作为声刺激，用鼓膜电极记录检测１０例正常人和１０例有眩晕症状患者双耳的耳蜗电图。当在屏蔽好、被检者处于良好的安静状态下，选择适合的滤波条件，能记录到有频率特性的ＳＰ；正常人的短声和０．５、１、２ｋＨｚ短纯音诱发的－ＳＰ／ＡＰ平均值较小，两者有显著性差异（Ｐ＜０．０５），而４、６和８ｋＨｚ短纯音诱发的－ＳＰ／ＡＰ值比较无显著性差异（Ｐ＞０．０５）。正常人组８５％（１７／２０）短纯音诱发的为－ＳＰ，１５％（３／２０）为＋ＳＰ。提示眩晕患者的－ＳＰ／ＡＰ值有频率特性的差异，也反映了＋ＳＰ在诊断膜迷路积水中可能有特殊意义。     

梅尼埃病听力损失程度和类型对短声诱发的SP/AP比值的影响

目的 :探讨耳蜗电图 (ECoch G)在梅尼埃病诊断中听力损失程度和类型 ,对交替短声诱发的负性总和电位 (SP)与动作电位 (AP)比值 (SP/ AP)的影响。方法 :采用鼓膜电极耳蜗电图描记术 ,对梅尼埃病 90耳 (梅尼埃病组 )和其他原因感音神经性聋 6 0耳 (感音神经性聋组 )及正常听力 5 0耳 (正常对照组 )记录了 AP和 SP各参数 ,对结果进行对照分析。结果 :AP潜伏期 3组差异无显著性 ,AP振幅正常对照组高于梅尼埃病组和感音神经性聋组 (P <0 .0 5 ) ,SP振幅正常对照组高于感音神经性聋组 (P <0 .0 1)而低于梅尼埃病组 (P <0 .0 1)。SP/ AP振幅比值梅尼埃病组 (48.0 9± 14 .38) % ,明显高于感音神经性聋组 (2 0 .0 2± 15 .0 0 ) %和正常对照组 (2 3.85±8.0 5 ) % ,(均 P <0 .0 1)。梅尼埃病组 SP/ AP比值与主观纯音听阈呈正相关 (r =0 .5 6 0 1,P <0 .0 1) ,其异常率为 73%。梅尼埃病不同听力损失组中 ,SP/ AP比值轻度耳聋组低于中度和中重度组 (均 P <0 .0 1) ,后两组差异无显著性意义 (P >0 .0 5 )。低频型低于平坦型 (P <0 .0 5 ) ,高频型和前两型相比差异无显著性意义。结论 :SP/ AP振幅比值异常增大有助于梅尼埃病的临床诊断 ,在一定范围内随听阈提高而增大 ,必须有足够的残余听力才能记录质量好的图形。     

耳蜗电图诊断梅尼埃病的灵敏度研究

目的：探讨耳蜗电图在梅尼埃病（MD）诊断中的应用价值。方法：将测试对象分为确诊、可能和疑似MD组,将可能和疑似MD组合并为可疑MD组。依据纯音听阈测试结果对确诊MD组患耳按听力损失程度进行病情分级。采用短声（click）和1 000、2 000、4 000Hz 3种频率tone burst（TB）分别对测试耳进行耳蜗电图测试,并计算和电位（SP）与听神经复合动作电位（AP）的振幅比值（SP/AP）,同时采用由click刺激声引出的AP疏波和密波潜伏期的差值（AP shift）辅助诊断。分别计算不同刺激声不同测试方法的诊断阳性率,比较MD的诊断阳性率。结果：确诊MD组click SP/AP阳性率为41.2%,TB 1 000、2 000、4 000Hz阳性率分别为80.4%、72.5%、37.3%,AP shift阳性率为45.1%。配对χ^2检验显示,TB 1 000 Hz与click SP/AP阳性率比较、TB 2 000Hz与click SP/AP阳性率比较均差异有统计学意义（均P〈0.01）,其中TB 1 000Hz诊断阳性率最高,即灵敏度最高。确诊MD组与可疑MD组患耳click SP/AP阳性率分别为41.2%和12.0%（P〈0.05）,AP shift阳性率分别为45.1%和8.0%（P〈0.01）,χ^2检验显示2组间click SP/AP和AP shift阳性率差异有统计学意义。结论：耳蜗电图在MD诊断及鉴别诊断中作用显著,特别是采用1 000Hz和2 000HzTB刺激声,其诊断灵敏度高达80.4%和72.5%。AP shift也被证明是一种有效的测量方法,在辅助诊断MD中作用显著。     

Electrocochleography in patients with Meniere's disease

OBJECTIVE: The objective of this study was to evaluate the role of electrocochleography (ECoG) in the diagnosis of Meniere's disease. STUDY DESIGN: This study is a retrospective case review. METHODS: Patients undergoing ECoG for Meniere's disease between 1995 and 2003 were identified and segregated as having definite , probable , or possible Meniere's disease according to the 1995 American Academy of Otolaryngology-Head and Neck Surgery guidelines for Meniere's disease classification. Those determined to have probable and possible Meniere's disease were then combined to form a less-than-definite group for statistical analysis. Electrocochleography summating potential (SP)/action potential (AP) ratios were determined, and ratios greater than 0.4 were considered abnormal. The 2 groups were then compared to assess for any correlation between ECoG with the 1995 American Academy of Otolaryngology-Head and Neck Surgery Meniere's disease classification. RESULTS: Sixty patients with definite Meniere's disease and 37 with less-than-definite Meniere's disease were identified. Overall, 59.8% had abnormally elevated SP/AP ratios. Of those with definite Meniere's disease, 66.7% had abnormally elevated SP/AP ratios, whereas of those with less-than-definite Meniere's disease, 52.7% had abnormal ECoGs ( P = .069). CONCLUSIONS: A significant difference in ECoG results was not seen between the definite and less-than-definite Meniere's disease groups. Furthermore, approximately 30% of those with definite Meniere's disease would not be classified as having Meniere's disease based on ECoG results. Because of its lack of sensitivity, ECoG should not play a decisive role in determining the presence or absence of Meniere's disease.     

Amplitude effects on electrocochleography outcomes

OBJECTIVE: Electrocochleography measures in humans were examined to determine factors affecting results. STUDY DESIGN: Retrospective study. METHODS: Analysis was performed on data from 479 patients seen from 1998 to 2002 who underwent electrocochleography with a tympanic membrane electrode. Measures from click evoked electrocochleography (the summating potential to action potential ratio [SP/AP]) were compared with tone evoked electrocochleography (the SP amplitude). RESULTS: Findings indicate a strong correlation between click and tone measures if the AP from click measures was over 1 microV (P <.001), but no significant correlation between these measures if the AP was under 1 microV. Results were also analyzed with respect to patient hearing sensitivity and final diagnosis. CONCLUSION: Tympanic membrane electrocochleography is more efficacious when the AP from click stimulation is over 1 microV.     

Tympanic electrocochleography for evaluation of endolymphatic hydrops.

There has been increased interest in electrocochleography for the diagnosis and intraoperative monitoring of patients with endolymphatic hydrops. Attention has been focused on the determination of the summating potential:action potential (SP:AP) ratio from alternating polarity clicks. Review of this technique at the University of Minnesota led to a reevaluation of the usual interpretation of these recordings. Separate examination of the rarefaction and condensation click recordings provides insight into abnormal response patterns. Cases are presented to illustrate a variety of normal and abnormal patterns including abnormal differences in the latency of condensation and rarefaction-click-generated action potentials, increased summating potential, uncanceled cochlear microphonic, and reduced action potential and summating potential amplitudes. These response categories may be useful in understanding the pathophysiology of Meniere's disease.     

短纯音诱发的听性脑干反应测试中声诱发短潜伏期负反应研究

目的 总结在有听力损失儿童中行短纯音诱发的听性脑干反应(tbABR)测试时记录到的声诱发短潜伏期负反应(acoustically short latency negative response,ASNR)的特点.方法 在有听力损失的0～6岁儿童中应用SmartEP听觉诱发电位仪记录短声和短纯音ABR的反应阈,在记录到ASNR的受试者中分析其反应阈和潜伏期.结果 在所有80受试耳中共7耳(8.75%)在cABR测试中引出ASNR,40耳(50%)在tbABR测试中引出ASNR,其中1 kHz引出率最高(37耳,46.25%),2 kHz次之(25耳,31.25%).引出ASNR者ABR波V反应阈最低65 dB nHL,ASNR反应阈最低80 dB nHL.0.5、1、2和4 kHz短纯音诱发的ASNR潜伏期分别为6～8、5～7、3～5、3～4 ms.随刺激强度的增加,其潜伏期缩短.结论 有听力损失的儿童tbABR测试中可以记录到AS-NR,但不影响以波V反应阈评估听力.     

ELECTROCOCHLEOGRAPHY IN ENDOLYMPHATIC HYDROPS USING TONE-PIP AND CLICK STIMULI

The use of electrocochleography (ECochG) in the identification of endolymphatic hydrops in Menière's disease, using either trans-tympanic or extra-tympanic recording techniques, has become very popular. The presence of an enhanced summating potential (SP) component is considered to be a diagnostic indicator of hydrops. The response evoked by a click stimulus is widely used in this investigation. The aim of this study was to assess the value of tone-pip stimuli for measurement of the SP component in patients with suspected Menière's disease. Extra-tympanic ECochG was recorded from a surface electrode positioned on the postero-inferior quadrant of the ear canal close to the tympanic annulus. Forty patients referred to the Evoked Potentials Clinic at the Queen's Medical Centre were studied. The combined summating potential and action potential waveform (SP/AP) were recorded using click and tone-pip stimuli. The pips had tone frequencies of 1 and 4 kHz and all stimuli were presented with alternating phase at a repetition rate of 10 per second. The percentage SP (%SP), width and latency characteristics of the SP/AP waveform were calculated for each stimulus condition. There were four patients (10%) with an enhanced tone-pip %SP when the click %SP was within normal limits. Width measurement of the tone-pip waveform at the onset point of the response was abnormal in 13 patients (33%) when a similar measurement of the click-evoked response was normal. There were nine of these patients identified by an abnormal width measurement at the 50% amplitude point of the SP/AP waveform. Both tone-pip frequencies were required in order to identify all these abnormal measurements. In conclusion, the tone-pip response provides valuable additional information to the click stimulus in support of the diagnosis of endolymphatic hydrops.     

A clinical study of electrocochleography in Menière's disease

Electrocochleography (ECochG) of 168 ears with definite Meniere's disease was studied. The results were compared with recordings from 29 normal ears and 444 ears with other types of sensorineural hearing loss. It is shown that the SP/AP ratio is much more useful than SP amplitude for detecting endolymphatic hydrops. There was little difference in the mean values of SP/AP from those proposed by many other investigators; the mean values all being near 0.25. From 0.30 to 0.40 of SP/AP was considered adequate as the upper limit. Following intravenous administration of glycerol, a significant decrease in SP/AP was found in 21 Meniere's ears. However, there was no change of SP/AP after oral administration of glycerol and isosorbide. This difference may be due to the fact that a larger oral than intravenous administration is necessary to affect SP/AP. Although a postoperative decrease of 10% or more in SP/AP was observed in 5 patients, 10 patients followed up for 2 years or more after surgery did not show a statistically significant change of SP/AP and pure tone threshold. ECochG should be repeatedly recorded to be useful as a monitor for the presence of hydrops. It is discussed whether biochemical or mechanical changes in endolymph may cause a decrease in SP/AP after the use of dehydrating agents and endolymphatic sac surgery.     

Effects of inner ear immune responses on auditory function in guinea pigs]

Following direct challenge with KLH antigen primary or secondary (after systemic immunization) to the ES (endolymphatic sac) in guinea pigs, ECoG (electrocochleograms) were recorded from the round window induced by click and tone pips. The recordings were carried out on the 2nd, 7th and 21st days after local antigen challenge. There were no abnormal findings in the ECoG of the primary antigen challenged animals. On the other hand, prolongation of latencies, decrease in amplitudes of APs (compound action potentials) and increases in SP/AP ratios were observed in the 2nd day recordings of the secondary antigen challenged animals. However, all parameters of ECoG in the 7th day recordings were normal. Decreases in AP amplitudes were again found in the 21st day recordings. The ECoG findings with click and tone pip stimulation showed similar results. From these findings, in conjunction with morphological observations, it is speculated that these ECoG findings are caused by immuno-injury to the ES and cochlea, as well as the resultant endolymphatic hydrops which develops acutely and gradually subsides after secondary challenge.     

Electrocochleography in an experimental animal model of acute endolymphatic hydrops

A reliable animal model of acute type of endolymphatic hydrops was made with injection of artificial endolymph into the cochlear duct. In 12 animals without Reissner's membrane rupture, the endolymphatic potentials (EP) were kept normal after injection of artificial endolymph, but their electrocochleography (ECoG) showed as: a rise of summating potentials (SP) amplitude, a decrease of action potentials (AP) amplitude, an increase of SP/AP ratio, as well as a delay of N1 latency. In 7 animals with membrane rupture, the EP significantly decreased. ECoG showed as: a decrease of hearing function in all test frequencies, a distortion of SP-AP wave and even a loss of AP. Based on the results of our experiment it can be assumed that the dominant -SP may be seen in the acute stage of endolymphatic hydrops without a rupture of Reissner's membrane. Therefore, the dominant -SP may only be of value in the clinical diagnosis during episodic vertigo and fluctuating hearing loss of Meniere's disease.     

External aperture of the vestibular aqueduct in Meniere's disease

OBJECTIVE: To study the relationship of the length of the external aperture of the vestibular aqueduct and the ratio of the summating potential and action potential (SP:AP) in patients with Meniere's disease. STUDY DESIGN: Retrospective case study. SETTING: Neurotology referral center. PATIENTS: Fifty-four patients with Meniere's disease and nine control subjects without Meniere's disease. INTERVENTION: The external aperture of the vestibular aqueduct was measured from a three-dimensional surface reconstruction computed tomography scan. Transtympanic electrocochleography was performed on patients with Meniere's disease. MAIN OUTCOME MEASURE: The length of the external aperture of the vestibular aqueduct in the Meniere's disease ears was related to the SP:AP ratio in the Meniere's disease ears and compared with controls. RESULTS: The average length of the external aperture was 3.79 +/- 2.92 mm in Meniere's disease ears and 5.35 +/- 1.73 mm in the control ears (p < 0.05). An enlarged SP:AP ratio was found in 95% of ears in the group with nonvisible external apertures of the vestibular aqueduct, 91% of ears in the <5 mm group, 58% of ears in the 5-7 mm group, and 29% of ears in the >7 mm group (chi-square = 24.814; p = 0.000). CONCLUSIONS: The length of the external aperture of the vestibular aqueduct in patients with Meniere's disease is significantly shorter than in those without Meniere's disease. Endolymphatic hydrops, evidenced by an enlarged SP:AP ratio, was related to the length of the external aperture of the vestibular aqueduct. The shorter the external aperture, the more often the SP:AP ratio was enlarged. A short or nonvisible external aperture of the vestibular aqueduct is a predisposing factor to the development of Meniere's disease.     

Elevated summating potential in a case of posterior fossa meningioma was normalized by tumor removal

OBJECTIVE: A change in the summating potential (SP) obtained from a patient with posterior fossa meningioma associated with surgical removal of the tumor was reported and possible mechanisms underlying the change are discussed. METHODS: This paper is a retrospective case review. A tertiary care referral center was the setting for the study. The authors present a 46-year-old female patient with posterior fossa meningioma, which was removed surgically. Pure tone audiometry and electrocochleography (ECoG) were performed before and after surgical removal of the tumor. RESULTS: Pure tone audiogram showed normal hearing levels before surgery, and there were no apparent postoperative changes in hearing levels. ECoG showed a normal compound action potential (AP) level and an elevated SP/AP ratio (0.53) before surgery. After the tumor removal, the SP/AP ratio became 0.16, which was a normal level in our department. CONCLUSIONS: The increased SP/AP ratio was normalized after surgery. Possible mechanisms underlying the increase in SP/AP ratio are an inhibition of the olivocochlear bundle function and endolymphatic hydrops.     

Electrocochleography in the presence and absence of perilymphatic fistula.

The purpose of the present study was to evaluate the effect of an acute perilymphatic fistula on the amplitude ratio (SP/AP) of the summating potential (SP) and action potential (AP). The effect of the acute fistula on AP threshold was also addressed. Electrocochleographic recordings were obtained before and immediately after surgical laceration of the round window membrane in 19 guinea pigs. Stimuli comprised clicks and 2,000-Hz and 8,000-Hz tone bursts, presented initially at 100 dB peak equivalent sound pressure level and in descending 10-dB steps. After fistula induction the SP/AP significantly increased for the click and 8,000-Hz tone burst stimuli but not for the 2,000-Hz tone burst stimuli. No significant change in AP threshold occurred. These findings suggest that the SP/AP may be sensitive to perilymphatic fistula, at least in guinea pigs. The changes in the SP/AP do not appear to be related to changes in threshold.