Auditory brainstem response and magnetic resonance imaging for acoustic neuromas: costs by prevalence

OBJECTIVE: To compare hypothetical costs for identification of acoustic tumors when using magnetic resonance imaging with gadolinium Gd 64 (MRI-(64)Gd) as a sole diagnostic test and when using auditory brainstem response (ABR) testing followed by MRI-( 64)Gd (ABR + MRI-(64)Gd) for those with positive ABR findings. PATIENTS AND METHODS: Retrospective review of the medical records of 75 patients having surgically confirmed acoustic neuromas to categorize them into 3 subgroups relative to their risk of having a cerebellopontine angle tumor based on history, symptoms, and routine pure-tone and speech audiometric findings. Hypothetical costs associated with identification of patients with acoustic neuroma in each subgroup were calculated for MRI-(64)Gd alone and ABR + MRI-( 64)Gd. Auditory brainstem response sensitivity and specificity data for the 75 patients with acoustic neuroma and 75 patients without a tumor matched for hearing loss were applied to the hypothetical subgroups. Tumor size was considered also. SETTING: Tertiary care center. MAIN OUTCOME MEASURE: Comparison of costs for MRI-(64)Gd and ABR + MRI-(64)Gd. RESULTS: Fouteen patients with acoustic neuroma were assigned to the high-risk category (30% probability); 45 were in the intermediate-risk category (5% probability); and 16 were in the low-risk category (1% probability). Auditory brainstem response testing correctly identified 100% of the large tumors (>2.0 cm), 93% of the medium-sized tumors (1.1-2.0 cm), and 82% of the small tumors (<1.0 cm). The hypothetical costs for identifying 14 patients with acoustic neuroma among 47 patients in the high-risk category using MRI-(64)Gd would be $70,500; ABR + MRI-(64)Gd costs for the 13 patients identified by ABR would be $39,600. Hypothetically 900 patients would be tested to identify the 45 acoustic neuromas in the intermediate-risk category. Magnetic resonance imaging with (64)Gd screening would reach $1.35 million for this sample. Auditory brainstem response testing and MRI-(64)Gd would be $486,000, but 4 acoustic neuromas would be missed. For the low-risk subgroup MRI-6(4)Gd screening of 1600 patients to identify 16 acoustic neuromas would total $2.4 million; ABR + MRI-(64)Gd to identify 15 of them would be $787,500. In this sample of 75 acoustic neuromas, large tumors were more prevalent in the low-risk subgroup than in the high- or intermediate-risk subgroups. CONCLUSIONS: Decisions regarding assessment of patients at risk for acoustic neuromas must be made on a case-by-case basis. Use of ABR + MRI-( 64)Gd allows considerable savings when patients are in the intermediate- or low-risk subgroups. New MRI and ABR testing techniques offer promise for reducing costs.     

两种听觉监护在听神经瘤术中的联合应用及评价

目的　探讨听神经瘤手术中听觉监护的意义。比较听性脑干反应（ABR）和蜗神经动作电位（cochlear nerve action potential,CNAP）在听觉监护应用中的价值。方法　回顾性分析我中心12例保留听力手术的听神经瘤患者资料及术中情况,患者术前均有实用听力（AAO-HNS分级A级、B级）,可引出ABR波形,V波分化可,所有手术均采取乙状窦后径路摘除肿瘤。所有患者均全程ABR监护,术中打开脑膜后联合监测CNAP。结果　手术过程中所有患者ABR波形较术前基线均有不同程度的变化,可记录到V波潜伏期均较基线延长（0.68±0.41）ms。CNAP波幅个体差异性较大,可记录到的P1潜伏期均较基线延长（0.25±0.16）ms。12例中有8例（66.7%）患者术后保留可用听力;另外4例（33.3%）术后达不到可用听力,此4例患者ABR表现为3例V波消失,1例V波潜伏期延长。CNAP表现为2例CNAP的P1消失,2例P1延长。电钻钻磨造成的震动和噪声、手术时神经被牵拉或热损伤后等急性损伤后ABR和CNAP波幅均出现短时间急剧下降,手术暂停5 min后,部分患者波幅可在一定程度恢复。结论　听神经瘤手术中ABR和CNAP对于听觉监护均有一定意义。ABR波形稳定可靠,但叠加时间相对较长;CNAP叠加快速,可提升监测灵敏度,但波形变异度较大。电钻钻磨造成的震动和噪声、操作过程中对神经组织的牵拉以及热损伤均被及时监控,两者联合应用可提升听神经瘤手术的听觉功能保留率。     

The stacked ABR: a sensitive and specific screening tool for detecting small acoustic tumors

The failure of standard ABR measures to detect small (< or =1 cm) acoustic tumors has led to the use of enhanced magnetic resonance imaging (MRI) as the standard to screen for small tumors. This study investigates the suitability of the stacked ABR as a sensitive screening alternative to MRI for small acoustic tumors (SATs). The objective of the study was to determine the sensitivity and specificity of the stacked ABR technique for detecting SATs. A total of 54 patients with acoustic tumors identified by MRI that were either < or =1 cm in size or undetected by standard ABR methods, irrespective of size, were studied. A control population of 78 nontumor normal-hearing subjects was also tested. For comparison, two standard ABR measures (IT5 and I-V delay) were also analyzed. The stacked ABR demonstrated 95% sensitivity and 88% specificity; 100% sensitivity was obtained at 50% specificity. Standard ABR measures were much poorer in detecting these tumors. In conclusion, the stacked ABR can be used as a sensitive, widely-available, cost-effective, and comfortable tool for screening SATs.     

397例听神经瘤听力特征分析

目的 分析听神经瘤患者听力学特征,为筛查听神经瘤提供参考依据。方法 回顾性分析2019年8月—2022年4月诊治的397例单侧听神经瘤患者临床资料,所有患者均行纯音测听、声导抗测试、言语识别率(SDS)、畸变产物耳声发射(DPOAE)、听性脑干诱发电位(ABR)和颅脑增强MRI。结果 以典型症状就诊者312例,非典型症状就诊者85例。以突发性聋就诊者25例;患耳听力正常者54例,包含大型甚至特大型肿瘤,99例全聋者亦包含内听道和中型肿瘤。5例全聋者言语识别能力未完全消失。DPOAE一致型245例,耳蜗型72例,蜗后型79例。ABR阳性率98.0%(389/397),8例ABR波形正常者中3例为双侧非对称听力损失。结论 非典型症状就诊者占比21.4%,以突发性聋就诊、听力正常或ABR正常者不能排除听神经瘤;DPOAE和ABR可作为筛查听神经瘤的重要检查方法。     

ABR screening for acoustic neuromata: the role of rate-induced latency shift measurements.

The audiological assessment of patients considered 'at risk' for an acoustic neuroma is problematic when the patient has a severe hearing loss. The utility of ABR rate-induced latency shift (RLS) measurements was investigated in 189 patients who had passed a conventional assessment and 31 patients with an acoustic neuroma. A test based on the RLS of wave V using rates of 11.1 s-1 and 88.8 s-1 had a sensitivity of 89.5% and a specificity of 90.8% when applied with a dual interpretive criterion which included the loss of wave V at the higher rate. This test was included in an ABR screening protocol which had a sensitivity of 100% and a specificity of 97.9%. The RLS test requires no correction for age, sex, hearing loss or stimulus intensity and may be used in patients with severe hearing loss for whom other ABR tests are inappropriate.     

听神经瘤的耳声发射观察

目的 观察和分析听神经瘤的耳声发射特点,为评估听神经瘤患者的耳蜗功能和选择保护听力的术式提供参考依据.方法 对20例（22耳）听神经瘤患者行纯音听阈、阻抗、听性脑干反应（auditory brainstem response,ABR）、诱发性耳声发射（evoked otoacoustic emissions,EOAE）测试及CT和（或）MRI扫描,能引出EOAE的瘤耳检测其自发性耳声发射（spontaneous otoacoustic emissions,SOAE）和传出抑制功能.结果 28.57%听神经瘤耳能引出EOAE,按其畸变产物耳声发射（distortion product otoacoustic emissions,DPOAE）特点分为三型：①“耳蜗型”3耳;②“非耳蜗型”2耳;③“混合型”1耳;“非耳蜗型”耳能引出强大的SOAE;能引出EOAE的6耳均有内侧橄榄耳蜗传出系统功能障碍.结论 EOAE可精确分析听神经瘤患者的耳蜗（外毛细胞）功能,部分听神经瘤病人存在“离断耳”现象.耳声发射（otoacousticemissions,OAE）在诊断重度感音神经性聋（包括听神经瘤病人）方面有一定潜能.     

Changing concepts of acoustic neuroma diagnosis

Three hundred five acoustic neuromas were reviewed to determine the sensitivity of combining the auditory brainstem response (ABR) and the intravenous contrast-enhanced computed tomogram (CT) as screening tests for acoustic neuroma diagnosis. The ABR detected 98% of the tumors. The enhanced CT demonstrated 97% of tumors larger than 1.5 cm, but only 48% of neuromas 1.5 cm or smaller. The combination of both ABR and enhanced CT, used as the initial screening tests, identified 99% of the neuromas. We conclude that ABR, with enhanced CT as needed, is an accurate screening protocol. This method can be used as an alternative to the traditional ABR, electronystagmography, and internal auditory canal tomograms.     

听神经瘤的再手术(附11例分析)

为进一步提高听神经瘤手术的临床疗效，对１５８例听神经瘤手术后１１例再次手术患者进行临床分析，发现肿瘤大小、切除方式以及手术进路与临床症状复发密切相关。肿瘤越大，复发机会越多；大部切除，次全切除及全切除的复发再手术率分别是１９．４％、１３．２％和０；迷路后进路手术复发再手术率最高，达３３．３％。防止临床复发最根本的措施是术中尽量减少肿瘤残留，力争全切。为达此目的要求早期诊断，选择适当的手术进路。对不能全切的较大肿瘤，次全切除能有效地延缓临床复发时间，减少并发症。计算了术前以及术后肿瘤的增长速度以及肿瘤倍增时间及再手术间期，建议术后每半年进行一次影像检查，对于早期发现复发有重要意义。Ｘ刀是对付早期肿瘤复发的有效办法。再手术中的并发症除损伤面神经外，其它少见。     

Normal auditory brainstem response in patients with acoustic neuroma

Auditory brainstem response testing has been a major breakthrough in audiologic screening for acoustic neuroma because of its high degree of sensitivity. Although it is not uncommon for other cerebellopontine angle masses to present with normal ABR findings, reports of eighth nerve tumors with false-negative auditory brainstem response tests are quite rare. A series of 120 acoustic neuromas resected at the University of Michigan was reviewed and revealed two such patients. These two patients presented with asymmetric sensorineural hearing loss and unilateral tinnitus and were found to have completely normal auditory brainstem response. The diagnosis of acoustic neuroma would have been delayed if a comprehensive evaluation had not been pursued.     

The sensitivity of auditory brainstem response testing for the diagnosis of acoustic neuromas

OBJECTIVES: To determine the sensitivity of auditory brainstem response (ABR) testing for detecting acoustic neuromas and to determine whether the test is less sensitive for detecting small tumors. DESIGN: Retrospective review of the medical charts of 58 patients with acoustic neuroma who had all of the data necessary for inclusion in the study. SETTING: University-affiliated referral practice of one neurotologist. PATIENTS: Patients with acoustic neuromas who had both ABR tracings and magnetic resonance imaging films available for review. MAIN OUTCOME MEASURES: Positive ABR and negative ABR results correlated with tumor size. RESULTS: Tumor size ranged from 0.4 to 7 cm. The overall sensitivity of ABR in diagnosing acoustic neuromas was 90%. However, ABR was progressively less sensitive with decreasing tumor size. Only 7 (58%) of the 12 tumors 1 cm or smaller were detected by ABR. CONCLUSION: Auditory brainstem response testing cannot be relied on for detection of small acoustic neuromas and should not be used as a criterion to determine whether magnetic resonance imaging should be performed when an acoustic neuroma is suspected clinically.     

神经耳科学检查对听神经瘤的诊断意义

目的：探讨神经耳科学检查对听神经瘤的诊断意义。方法：对１３例听神经瘤行纯音测听,声导抗,眼震电图,听性脑干诱发电位（ＡＢＲ）,耳蜗电图及面神经电图等神经电生理检查。结果：患侧纯音听阈１例正常,另４例２ｋＨｚ以下在正常范围,声导抗镫肌反射试验结果不一,冷热试验８例患侧半规管麻痹,均伴有一项或多项视－前庭眼动眼震异常;ＡＢＲ２例未能引出,敏感度为９０．９％;７例面神经电图异常;３例面神经电图异常;３例     

Evaluating the role of magnetic resonance imaging scans in the surgical management of acoustic neuromas

OBJECTIVE: To assess the reliability of magnetic resonance imaging (MRI) in predicting the size and position of an acoustic neuroma, with particular reference to the intracanalicular portion. STUDY DESIGN: Prospective study comparing the position of the tumor in the internal auditory canal on fast spin-echo MRI with the actual position measured intraoperatively. METHODS: The study was performed in a tertiary referral neurotology center, encompassing both the public and private health care systems. Fifteen consecutive patients admitted for acoustic neuroma removal via the translabyrinthine approach were studied. The main outcome measure was tumor position in the internal auditory canal expressed in millimeters, accurate to the nearest 0.5 mm. RESULTS: The fast spin-echo MRI was accurate within an error of 1 mm in predicting the lateral extent of the tumor in the internal auditory canal. CONCLUSION: Fast spin-echo MRI can accurately predict the lateral extent of an acoustic neuroma and allow accurate planning of the surgical approach.     

听神经瘤的再手术（附11例分析）

为进一步提高听神经瘤手术的临床疗效，对１５８例听神经手术后１１例再次手术患者进行临床分析，发现肿瘤大小，切除方式以及手术进路与临床症状复发密切相关，肿瘤越大，复发机会越多；大部切除；次全切除及全切除的复发再手术率分别是１９．４％、１３．２％和０，迷路后进路手术复发再手术率最高，达３３．３％，防止临床复发最根本的措施是术中尽量减少肿瘤残留，力争全切。为达此目的要求早期诊断，选择适当的手术进路，对不能     

Disposable electrodes in auditory brainstem response audiometry

Since the first applications of auditory evoked potentials to neuro-otological diagnosis and objective audiometry, many advances have been made in electrode technology, including the development of disposable electrodes. This paper describes the use of pre-gelled disposable electrodes in auditory brainstem response audiometry (ABR), this test being employed as part of a screening procedure for acoustic neuroma. Factors of patient safety, clinical time and cost are discussed. The use of disposable electrodes is considered a beneficial advance in the ABR test technique.     

以突发性听力减退为首发症状的听神经瘤临床特点分析

目的 分析突发性听力减退为首发症状的听神经瘤的临床特点,以避免对该病的误诊、误治。方法 对1983－1997年收治听神经瘤92例中20例（21耳）首发症状为突发性听力减退的病例占21.7%)进行回顾性分析。结果 听力学检测：纯音听阈（500Hz、1000Hz、2000Hz听力平均听阈）＞71dBHL者12耳,占57.1%;听性脑干反应（auditory brainstem r esponse,ABR)检测均有异常;声反射检测9例（10耳）均消失。影像学检查CT阳性率为88.89%,阴行者行CT气脑造影或磁共振成像（magnetic resonance imaging,MRI)检查均能确诊。结论 对突发性听力减退可疑听神经瘤的患者应常规检查ABR,出现异常者应进行颞骨CT,必要时行MRI检查。     

以突发性听力减退为首发症状的听神经瘤临床特点分析

目的分析突发性听力减退为首发症状的听神经瘤的临床特点,以避免对该病的误诊、误治。方法对1983～1997年收治听神经瘤92例中20例（21耳）首发症状为突发性听力减退的病例（占21.7%）进行回顾性分析。结果听力学检测纯音听阈（500Hz、1000Hz、2000Hz听力平均听阈）＞71dBHL者12耳,占57.1%;听性脑干反应（auditorybrainstemresponse,ABR）检测均有异常;声反射检测9例（10耳）均消失。影像学检查CT阳性率为88.89%,阴性者行CT气脑造影或磁共振成像（magneticresonanceimaging,MRI）检查均能确诊。结论对突发性听力减退可疑听神经瘤的患者应常规检查ABR,出现异常者应进行颞骨CT,必要时行MRI检查。     

Auditory brainstem response – a valid and cost-effective screening tool for vestibular schwannoma?

Conclusion: Contemporary auditory brainstem response (ABR) is not valid as a screening tool for VS, when considering the sensitivity of 80%, the specificity of 77%, and the positive predictive value of 3.4%, MRI screening is superior to ABR in Denmark when considering cost-effectiveness.

Objectives: The aim of this study is to assess the sensitivity, specificity, and cost-effectiveness of ABR vs MRI, when screening for VS in a clinical setting. Method: Data was collected on all patients subjected to an ABR during a 3-year period (2005–2008) at a tertiary referral center. The data were compared to results of MRI and with data from The Danish National VS Database. In total, 1447 adults underwent ABR, of whom 349 were referred for a subsequent MRI. Sensitivity and specificity were calculated. To assess the cost-effectiveness of ABR vs MRI, procedure costs for ABR and MRI were retrieved from the National Board of Health. Results: Twelve (3.4%) of 349 patients were diagnosed with a VS. Of the 1098 patients not referred for MRI, three (0.3%) were later diagnosed with a VS. The sensitivity and specificity of ABR in diagnosing a VS were 80% and 77%, respectively. Procedure costs were 326?EURO for the ABR and 319?EURO for the MRI.     

Contralateral auditory brainstem response abnormalities in acoustic neuroma

Contralateral Auditory Brainstem Response (ABR) findings in a series of 79 patients with unilateral acoustic neuroma are presented. Sixty-four patients (81 per cent) had a normal contralateral ABR, thirteen (16.4 per cent) had latency abnormalities contralaterally and in two patients (2.6 per cent) no consistent responses could be recorded despite good hearing. Abnormalities in the contralateral ABR were analysed and five patients had abnormal III-V interwave intervals, in seven patients the I-III intervals were abnormal and in one patient, only the fifth wave was present and of abnormal latency. The tumour size was assessed by computed axial tomography (CT) and the relationship between tumour size and contralateral ABR findings established. Large tumours (greater than 2.5 cm.) were associated with contralateral ABR abnormalities in 25.6 per cent of the patients, medium tumours (1.0-2.5 cm.) with ABR abnormalities in 14 per cent and there were no abnormalities in the small group (intracanalicular). The implications for interpretation of ABR recordings contralateral to an acoustic neuroma are discussed in relation to brainstem compression and its effect on the wave generator sites.     

Nerve origin of the acoustic neuroma.

Two hundred and seventy-one Japanese patients who underwent surgical removal of neuroma from the cerebello-pontine angle using the translabyrinthine approach were retrospectively reviewed in order to investigate the nerve origin on an anatomical basis. In 269 out of the 271 cases, the origin of the neuromas was identified. Among these cases, 84.8 per cent of tumours originated from the inferior vestibular nerve (IVN), followed by the superior vestibular nerve (SVN) (8.9 per cent). Of the 5.6 per cent of tumours arising from the vestibular nerve, however, it could not be determined whether they originated from the SVN or IVN. Two cases of neuromas originating from the facial nerve were seen (0.7 per cent). No neuroma arose from the cochlear nerve. Currently, the diagnosis of acoustic neuromas is best made with Gd-enhanced magnetic resonance imaging (MRI). However, our data indicate that the development of a functional test of the individual IVN can be useful for screening most cases of acoustic neuroma and in facilitating their early diagnosis.     

扩大迷路径路切除经枕下径路手术后复发的听神经瘤

目的：探讨听神经瘤经枕下径路手术后复发、后经扩大迷路径路再次切除肿瘤的方法及效果。方法：对5例复发的听神经瘤患者，采用扩大迷路径路手术，在经典迷路径路的基础上，通过充分切除岩骨骨质扩大手术视野，将复发的肿瘤组织完全切除。结果：5例听神经瘤直径为2．5～4．0cm，均全部切除，无死亡病例，未发生颅内感染及脑脊液漏；面神经功能与术前一致；术后CT和MRI复查均显示无肿瘤残存，小脑、脑干位置恢复正常。经0．5～2年7个月的随访，至今未见复发，患者已恢复正常生活和工作。结论：枕下径路手术容易残留内听道内的肿瘤，再次手术采用扩大迷路径路可直接暴露肿瘤并到达脑干，既可避免瘢痕粘连区，方便定位面神经，又能全部切除复发的肿瘤，且具有创伤小、面神经功能保存完好等优点。