Auditory brainstem responses after out-of-hospital cardiac arrest: Are they useful for outcome prediction?

We evaluated whether we could predict the neurologic outcome in 55 out-of-hospital cardiac arrest patients using auditory brainstem responses (ABR). ABR patterns were classified into one of 3 types by evaluation of 5 components: type 1, with all 5 components; type 2, lack of at least one response between the 2nd and 5th components; type 3, with only the first component or no response. The relation between the ABR patterns on the 3rd day following resuscitation and the neurologic outcome on hospital discharge was evaluated. The specificity that the 5 awake patients had type-1 ABR was 38%. The sensitivity that the 10 brain dead patients had type-3 ABR was 60%. In the type-1 ABR patients, the negative predictive value that the patients were awake was 100%. In the type-3 ABR patients, the negative predictive value that the patients became brain dead was 90.9%. These results suggest that ABR on the 3rd post-resuscitation day may not be useful for predicting if patients are awake or become brain dead, although the loss of components may be a sign of morbidity, and the presence of the 2nd or later components indicates possible future prevention of brain death.     

后半规管阻塞前后豚鼠前庭及耳蜗功能的动态变化

目的 探讨机械性后半规管阻塞前后豚鼠前庭和耳蜗功能的动态变化。方法 采用２０只豚鼠建立单侧后半规管阻塞的动物模型,观察手术前后眼震电图,听性脑干反应,耳声发射等变化。结果 术后第１天,第３天豚鼠正弦摆动刺激术侧眼震反应,明显减术,术后第５天起双侧眼震恢复正常。术后早期ＡＢＲ阈值一度升高,第５天达高峰,ＡＢＲ阈值平均升高４．５ｄＢ。ＤＰＯＡＥ反应幅度无明显改变。结论 后半规管阻塞能选择性地消除后半规     

阻塞性睡眠呼吸暂停综合征的听觉脑干电反应

１９９１年１月至１９９８年１月共有８０例阻塞性睡眠呼吸暂停综合征患者在我科接受悬雍垂腭咽成形术治疗,其中４１例行听觉及脑干电反应测试。ＡＢＲ各波潜伏期,峰间期及Ｉ,Ｖ波波幅与下沉对照人群的测试结果相近,差异无统计学意义,表明阻塞性睡眠呼吸暂停综合征并非必须合并ＡＢＲ的异常。     

短音诱发听性脑干反应的特性观察

目的 了解短音（tone pip）诱发的听性脑干反应（TP－ABR）的特征及其各频率反应阈与纯音听阈的关系。方法 对正常听力青年人30耳分别采用短声（click）、短音（0.5、1、2、4、6、8kHz）测试，记录各自不同强度下ABR的波形，观察V波潜伏期的改变。结果 tone pip与常规click声诱发的ABR极为相似，均有很高的可重复性和可靠性；ABR反应阈均较其主观听阈高，尤其是频率越低，反应阈越高，低频个体差异较大；随频率（0.5-8kHz）和强度（40－120dB peSPL）增加Ⅰ波Ⅴ潜伏期递减；各频率的反应阈与音听阈均有较好的相关性。结论 短音刺激记录的TP－ABR具有频率特性，其反应阈在相应频率的客观听力评估中有应用价值。     

急性化脓性中耳炎豚鼠耳蜗形态和功能改变

对3只因听泡置管导致急性化脓性中耳炎发作的豚鼠进行了脑干诱发电位（ABR）测试和耳蜗Corti氏器扫描电镜观察。发现3只豚鼠患耳Corti氏器均有程度不等损害，ABR阈分别提高45、60和30dB。提承急性中耳炎可引起内耳形态和功能变化。文中对引起损害的机制进行了讨论。     

Acoustic Evoked Response Following Transection of the Eighth Nerve in the Rat

Summary ? Object. The auditory brainstem response (ABR) is the most widely used means of intra-operative monitoring of the integrity of the auditory nerve and brainstem pathways during surgery in the cerebellopontine angle (CPA). Reliability of this and other electrophysiological techniques has been questioned because of persisting potentials in direct nerve recordings despite complete eighth nerve section.  The study was designed to assess the extent to which an acoustic evoked response persists after the cochlear nerve is lesioned in the CPA of the adult rat.  Methods. The eighth nerve was exposed microsurgically via a lateral suboccipital approach without damage to surrounding structures. The auditory brainstem response to monaurally presented click stimuli was recorded using needle electrodes and a bandpass of 10 to 5000 Hz.  Findings. Complete sharp sectioning of the nerve in the CPA resulted in immediate disappearance of brainstem-generated potentials but persistence of a large primary, vertex-positive wave in all but one case. This response was also abolished in recordings three days later and after emptying the inner ear canal. Provided that the cochlea remained intact, two weeks later a single, vertex-positive potential in the latency range of wave Ia of the ABR reappeared, reaching its peak amplitude six weeks after sectioning of the nerve.  Conclusions. The short-latency electrical potential recorded following damage of the eighth nerve in the cerebellopontine angle can be mistaken for an indication that nerve function is still preserved. The evoked injury potential is probably the major contributor to this potential that resembles wave I of the ABR. Monitoring of functional auditory integrity must neither be limited to early components of the ABR, nor to the electrocochleogram (EcoG) and the peripheral compound nerve action potential (CNAP), respectively.     

噪声习服对听觉损伤保护作用

目的探讨噪声习服对听觉损伤的保护作用。方法取健康成年豚鼠40只，随机分为正常对照组、噪声习服组、噪声损伤暴露组和噪声习服后损伤暴露组。建立噪声习服实验动物模型。采用听觉电生理测试和耳蜗基底膜铺片的方法，分别测定听性脑干反应（ABR）阈值及毛细胞缺失率的变化。结果噪声习服暴露对其后强噪声损伤暴露引起的听力损失产生了13dB的保护作用。耳蜗基底膜铺片显示，本实验中暴露引起的毛细胞缺失较明显，习服后损伤暴露组与直接损伤的暴露组相比基底膜第Ⅰ、Ⅱ圈的毛细胞缺失减少。结论采用适宜的噪声暴露参数，噪声习服暴露可对其后强噪声损伤暴露引起的听力损失产生保护作用。噪声暴露引起的毛细胞形态学改变包括细胞缺失和非致死性细胞损伤。噪声习服暴露后减少其后强噪声损伤暴露引起的毛细胞缺失。     

The influence of epidural anesthesia on the hearing system after normal labor

Abstract

Objective: The purpose of our study was to evaluate the influence of epidural anesthesia on the hearing system in women undergoing normal labor. Design: We examined two groups of patients: women with epidural anesthesia underwent four tests of distortion product otoacoustic emissions(DPOAEs): on admission, and fifteen minutes, one hour, and three hours after the last epidural bolus of local anesthetic. Auditory brainstem response (ABR) tests were performed on admission, and one hour, and three hours after the last epidural bolus. Women who gave birth without epidural anesthesia underwent DPOAEs tests on admission, during a uterine contraction, during active delivery, and three hours after labor. ABR tests were performed on admission, during a uterine contraction, and three hours after labor Study sample: twenty patients participated in the study. Twelve gave birth with epidural anesthesia and eight without anesthesia. Results: No significant changes in DPOAEs and ABR recordings were found between the two groups. Conclusions: Epidural anesthesia does not impair the sensory or the neural elements of the hearing system and therefore does not influence hearing.

Sumario

Objetivo: El propósito de este studio fue evaluar la influencia de la anestesia epidural en el sistema auditivo de mujeres en trabajo de parto normal. Diseño: examinamos dos grupos de pacientes: uno de mujeres con anestesia epidural, realizaron cuatro pruebas con emisiones otoacústicas por productos de distorsión (DPOAE): al ingreso y a los 15 minutos, una hora y tres horas después del último bolo de anestesia local epidural. También se obtuvieron Respuestas Auditivas de Tallo Cerebral (ABR) al ingreso y una y tres horas después del último bolo epidural. Al grupo de mujeres que dieron a luz sin anestesia epidural se les practicaron pruebas de DPOAE al ingreso, durante una contracción uterina durante el parto activo y tres horas después del mismo. También se hicieron pruebas de ABR al ingreso, durante una contracción uterina y tres horas después del parto. Muestra de estudio: veinte pacientes participaron en el estudio. Doce dieron a luz con anestesia epidural y ocho sin anestesia. Resultados: No se encontraron cambios significativos en los registros de las DPOAE y de las ABR entre los dos grupos. Conclusiones: La anestesia epidural no afecta los elementos sensoriales y neurales del sistema auditivo y consecuentemente, no influencia la audición     

Chloral hydrate sedation for auditory brainstem response (ABR) testing in children: Safety and effectiveness

IntroductionThe auditory brainstem response (ABR) test is used to identify hearing loss and measure hearing thresholds of infants and children who cannot be tested using standard behavioral hearing testing methods. In order for the ABR to yield useful data, a child must be asleep throughout the duration of the test. In many centers, this is achieved through the use of a general anesthetic, with its inherent risks and costs. Since 2004, ABRs have been routinely conducted at BC Children's Hospital in an ambulatory care setting under oral chloral hydrate sedation, with monitoring by a specialist nurse. The aim of this retrospective study was to assess the effectiveness and safety of nurse-led sedation with chloral hydrate for ABR testing at our tertiary pediatric center.MethodsMedical and audiology records were reviewed for children aged 6 months to 17 years who underwent ABR testing from 2004 to 2012. We reviewed the dosage of drug used, condition of the child after chloral hydrate administration, adverse effects, audiological results, patients’ vital signs, and the effectiveness of the sedative in keeping the child asleep throughout the duration of the test. Frequency distributions were derived for adverse outcomes.Results725 ABR records encompassing 635 children (multiple ABR tests in some children) were reviewed. The average dose of chloral hydrate used was 52 mg/kg. The majority of sedated ABR's (80.8%) were completed without any incident. Significant events [apnea and/or bradycardia], minor complications [vomiting, hypoxemia, prolonged sedation, and/or tachypnea] and restlessness were noted in 3.4%, 6.2%, and 5.0% of the cases, respectively. The majority of these issues resolved without medical intervention, such as the need to provide supplementary oxygen. In 95.9% of ABRs, chloral hydrate was successful in sedating the child adequately to answer the audiological question.ConclusionsThis forms the largest study to date on oral sedation for ABR testing. Based on our results, the use of chloral hydrate in the presence of a sedation nurse was a safe and reliable method of performing ABR in infants and children. This may be of significant value to centres worldwide exploring alternatives to general anesthesia for ABR testing.