视觉诱发电位和脑干听觉诱发电位无创监测颅内压的可行性

目的：观察在不同颅内压（ＩＣＰ）压力水平时视觉诱发电位（ＶＥＰ）和脑干听觉诱发电位（ＢＡＥＰ）的变化。方法：１０只家兔麻醉后建立急性颅内压增高的实验模型，用硬脑膜外纤维光束传感器测量不同阶梯ＩＣＰ，同时观察ＶＥＰ和ＢＡＥＰ的相应变化。结果：ＶＥＰ的Ｐ１、Ｎ２波潜伏期延长与ＩＣＰ增高均成正相关（ｒ＝０．６２、ｒ＝０．６０，Ｐ〈０．０１），其波幅的变化与ＩＣＰ增高之间相关不良。ＢＡＥＰ的Ⅰ、Ⅲ、Ⅴ波潜     

地氟醚对脑干听觉诱发电位的影响

地氟醚是一种新的吸入麻醉药,目前国内外尚未见有关地氟醚对脑干听觉诱发电位（ＢＡＥＰ）影响的报道,本研究通过观察地氟醚麻醉时ＢＡＥＰ变化,评价ＢＡＥＰ用于监测地氟醚麻醉深度的可行性。资料与方法研究对象　ＡＳＡⅠ～Ⅱ级、拟择期在全麻下行腹部手术的患者８例,年龄３５～５２（４６．９±６．１）岁,体重５０～７４（５９．６±８．５）ｋｇ,无心肺、神经、精神疾患及听力障碍,术前常规禁食饮。麻醉方法　病人入室后闭目静卧５分钟,开放静脉输液路（按５ｍｌ·ｋｇ－１·ｈ－１的速度滴注复方氯化钠液）,以２％利多卡因２…     

中潜伏期听觉甩电位与麻醉深度的判断

中潜伏期听觉诱发电位（ＭＬＡＥＰ）与多种全麻药有线性相关关系；并受手术刺激的影响而变化；以及与术中认知功能和对麻醉中事件的清楚记忆和模糊记忆有关，表明ＭＬＡＥＰ是判断麻醉深度的一个重要指标。     

苏芬太尼对气管内插管时血流动力学及血糖、皮质醇、胰岛素的影响

目的：以芬太尼作对照，观察使用苏芬太尼行气管插管时在血流动力学及血糖、血清皮质醇、胰岛素指标的变化。方法：３２例共分为两组，苏芬太尼组（ＳＦ）及芬太尼组（Ｆ）。分别在入室后、用药后、插管５、１５、３０分钟后记录ＳＢＰ、ＤＢＰ、ＭＡＰ，并抽静脉血测血糖、皮质醇及胰岛素浓度。结果：与诱导前相比，ＳＦ组给药至气管插管后的ＳＢＰ、ＭＡＰ、ＨＲ均降低，而Ｆ组的降低幅度不及ＳＦ组，两组相比，差异有显著性（Ｐ＜０．０５）。血糖及血清皮质醇浓度在给药及气管插管后ＳＦ组均降低，Ｆ组则升高，两组有显著性差异（Ｐ＜０．０５）。结论：在抑制麻醉诱导期的应激反应方面，苏芬太尼优于芬太尼。     

窒息豚鼠脑干听觉诱发电位变化窒息时限及其自然转归的实验研究

目的：了解不同窒息时限下豚鼠脑干听觉诱发电位（ＢＡＥＰ）的变化。方法：应用氯胺酮－甲苯噻嗪麻醉豚鼠２６只，随机分为三组，Ⅰ组窒息４分豚鼠８只，Ⅱ组窒息５分豚鼠８只，Ⅲ组窒息５．５分豚鼠１０只；记录窒息前、窒息后、解除窒息后ＢＡＥＰ各波及潜伏期的变化。结果：窒息后０．５分ＢＡＥＰ各波无明显变化，１．５～２分ＢＡＥＰ消失，Ⅰ组解除窒息后１分，Ⅰ、Ⅲ波出现，３分Ｖ波出现，６０分时潜伏期仍未恢复正常。Ⅱ组解除窒息后豚鼠死亡２只，余Ⅰ波１分出现，Ⅲ波３分出现，Ｖ波５分出现，到６０分各波潜伏期均明显延长Ｐ＜０．０５。Ⅲ组豚鼠全部死亡。结论：豚鼠能耐受窒息时限为４分，此时脑干听觉通路受到一定影响。     

静吸复合麻醉中不同小剂量芬太尼对脑电边缘频率和双波谱指数的影响

目的 研究静吸复合麻醉中不同小剂量芬太尼对脑电边缘频率（ＳＥＦ）和双小的指数（ＢＩＳ的影响。方法 随机将ＡＳＡⅠ～Ⅱ级病人３０例分为Ⅰ、Ⅱ、Ⅲ组地全麻诱导吸入安氟醚达０．８ＭＡＣ后三组分别静注芬太尼３μｇ．ｋｇ＾０－１、５μｇ．ｋｇ＾－１,于给药后６ｍｉｎ记录每组病人的ＭＡＰ、ＨＲ、ＳＥＦ及ＢＩＳ。结果 三组 内、组间ＭＡＰ、ＨＲ相比均无显著差异（Ｐ〈０．０５）,ＢＩＳ无显著性差异（Ｐ〉０．０５）     

侧脑室注射河豚毒素和藜芦定对大鼠异氟醚MAC的影响

目的 观察侧脑室注射河豚毒素（ＴＴＸ,钠通道阻断剂）或（和）藜芦定（ＶＥＲ,钠通道激动剂）对大鼠异氮醚最低肺泡有效浓度（ＭＡＣ）和翻正反射恢复时间的影响。方法 大鼠侧室置管后２ｄ,进行ＭＡＣ测定。４０只ＳＤ大鼠随机分为５组：生理盐水（ＮＳ）组、ＴＴＸ组、含４％二甲亚砜生理盐水（ＭＤＳＯ）组,ＶＥＲ组和ＶＥＲ＋ＴＴＸ组。测定每组大鼠侧脑室给药前和给药后ＭＡＣ,ＭＡＣ测定结束后记录大鼠翻正反射恢复时间     

中潜伏期听觉诱发电位在麻醉深度监测中的应用

术中知晓在全麻手术中日益受到重视,研究发现中潜伏期听觉诱发电位（ＭＬＡＥＰ）的潜伏期和波幅与麻醉药呈剂量依赖性抑制。本文综述了ＭＬＡＥＰ在麻醉深度监测中的应用。     

大剂量吗啡,芬太尼及纳络酮对犬冠脉血流影响的实验研究

实验用犬９只，开胸分离冠脉左旋支，安置电磁流量仪探头，监测冠脉血流量（ＣＢＦ）。同时用生理多异议监测左室收缩压（ＬＶＳＰ）、平均动脉压（ＭＡＰ）、心率（ＨＲ）和心电图（ＥＣＧ）。给药前各指标为对照值。第１组６只，静注吗啡２ｍｇ·ｋｇ－１和纳络酮０．１ｍｇ·ｋｇ－１加吗啡２ｍｇ·ｋｇ－１。第２组３只，静注芬太尼１００ｕｇ·ｋｇ－１。结果表明：吗啡使冠脉血流量增加５６．８％，同时有ＬＶＳＰ、ＭＡＰ下降，ＨＲ无变化。上述作用可被纳络酮部分拮抗。芬太尼使ＨＲ、ＣＢＦ、ＬＶＳＰ、ＭＡＰ 下降，对循环功能有一定抑制作用。提示大剂量芬太尼用于心脏患者麻醉要慎重。而吗啡有扩张冠脉作用，用于心脏患者麻醉有利于体外循环后心脏复跳，尤其对心肌缺血患者麻醉有益。     

异丙酚镇静下老年人中潜伏期听觉诱发电位的监测

既往研究表明中潜伏期听觉诱发电位 (ＭＬＡＥＰ)可以反应意识是否消失[1,2 ] ,但迄今尚无有关年龄增长是否会影响ＭＬＡＥＰ作为监测意识状态指标的可靠性及相关数据等方面的报道。本研究观察不同镇静水平下老年人年轻人ＭＬＡＥＰ的变化。资料与方法本研究对象为ＡＳＡⅠ～Ⅱ级 ,行下肢或下腹部手术的男性病人 ,年轻组 2 0～ 45岁 ,老年组 6 0～ 80年 ,每组各 2 0例。硬膜外阻滞麻醉平面维持在Ｔ4 以下 ,逐渐增加异丙酚静注速度 ,每个速度维持 15ｍｉｎ。每个恒定速度静注末采用ＮｉｃｏｌｅｔＶｉｋｉｎｇ ＩＶＳｙｓｔｅｍ记录ＡＥＰ ,…     

Multiparametric changes in the receptive field of cortical auditory neurons induced by thalamic activation in the mouse

The functional organization of the sensory cortex is constructed to process sensory information based on experience and learning. Importantly, it is plastic so that it can quickly adapt to environmental changes. Because the thalamus gates all ascending information, it is critical to understand how the thalamocortical system contributes to the plasticity of the sensory cortex. We show here that the neuronal receptive field (RF) in the auditory cortex faithfully tends toward the RF of the electrically stimulated auditory thalamic neurons. We characterized the RF of auditory neurons by measuring the best frequency, minimum threshold, bandwidth, RF area, and averaged response magnitude. All these parameters of the cortical RF showed robust changes toward the values of the parameters of the stimulated thalamic neuron following focal thalamic stimulation. Our data suggest that the thalamocortical system possesses intrinsic mechanisms that underlie the input specificity of learning-induced or experience-dependent cortical plasticity.     

The effect of temporal context on the sustained pitch response in human auditory cortex

Recent neuroimaging studies have shown that activity in lateral Heschl's gyrus covaries specifically with the strength of musical pitch. Pitch strength is important for the perceptual distinctiveness of an acoustic event, but in complex auditory scenes, the distinctiveness of an event also depends on its context. In this magnetoencephalography study, we evaluate how temporal context influences the sustained pitch response (SPR) in lateral Heschl's gyrus. In 2 sequences of continuously alternating, periodic target intervals and a more irregular baseline interval, the distinctiveness of the target was decreased in 1 of 2 ways--either by increasing the pitch strength of the baseline or by decreasing the pitch strength of the target. The results show that the amplitude of the SPR increases monotonically with the distinctiveness of the target. Moreover, SPR amplitude is greater for the sequence, where the pitch strength of the target is varied, compared with the condition, where the baseline is varied. Two subsequent experiments show that the amplitude of the SPR increases as duty cycle decreases, in a pitch "strength" contrast and in a pitch "value" contrast. These results indicate that the SPR adapts to recent stimulus history, enhancing the response to rare and brief events.     

Lateralization of dichotic speech stimuli is based on specific auditory pathway interactions: neuromagnetic evidence

Dichotic listening (DL) is a neuropsychological technique for the study of functional laterality. Based on behavioral patient studies, the "structural theory" states that lateralization of the auditory input during DL is allowed by an inhibition of the ipsilateral pathways. We aimed here at extending this theory to provide a neurophysiological basis of verbal DL. We investigated the magnetic responses of the primary auditory cortices elicited by dichotic consonant-vowel syllables. Dichotic stimuli consisted of 2 syllables pairs, a "competing" one composed by syllables with high spectral overlap (/da/ and /ba/) and a "noncompeting" pair (/da/ and /ka/). One of the syllables in each pair was delivered at 2 intensities, whereas the other did not change. A reduced increase of source intensity in response to dichotic pairs at the 2 levels was assumed to indicate pathway inhibition effects. We obtained that the left ipsilateral pathway (i.e., the left ipsilateral signal) was strongly inhibited by the right contralateral one. Conversely, the right ipsilateral pathway did not show an inhibition larger than the left contralateral one. These results extend the notion of auditory functional asymmetries by showing that beyond hemispheric functional specialization there is an asymmetry within the ascending auditory system, which is based on a competition mechanism. The larger the competition between the left and right ear stimuli, the larger are the inhibition effects, which determine the pathway asymmetry. These findings represent as well a neurophysiological basis for the "structural theory" explaining the right ear preference usually found in verbal DL tasks.     

Serial and parallel processing in the human auditory cortex: a magnetoencephalographic study

Although anatomical, histochemical and electrophysiological findings in both animals and humans have suggested a parallel and serial mode of auditory processing, precise activation timings of each cortical area are not well known, especially in humans. We investigated the timing of arrival of signals to multiple cortical areas using magnetoencephalography in humans. Following click stimuli applied to the left ear, activations were found in six cortical areas in the right hemisphere: the posteromedial part of Heschl's gyrus (HG) corresponding to the primary auditory cortex (PAC), the anterolateral part of the HG region on or posterior to the transverse sulcus, the posterior parietal cortex (PPC), posterior and anterior parts of the superior temporal gyrus (STG), and the planum temporale (PT). The mean onset latencies of each cortical activity were 17.1, 21.2, 25.3, 26.2, 30.9 and 47.6 ms respectively. These results suggested a serial model of auditory processing along the medio-lateral axis of the supratemporal plane and, in addition, implied the existence of several parallel streams running postero-superiorly (from the PAC to the belt region and then to the posterior STG, PPC or PT) and anteriorly (PAC-belt-anterior STG).     

Dynamics of auditory plasticity after cochlear implantation: a longitudinal study

Human representational cortex may fundamentally alter its organization and (re)gain the capacity for auditory processing even when it is deprived of its input for more than two decades. Stimulus-evoked brain activity was recorded in post-lingual deaf patients after implantation of a cochlear prosthesis, which partly restored their hearing. During a 2 year follow-up study this activity revealed almost normal component configuration and was localized in the auditory cortex, demonstrating adequacy of the cochlear implant stimulation. Evoked brain activity increased over several months after the cochlear implant was turned on. This is taken as a measure of the temporal dynamics of plasticity of the human auditory system after implantation of cochlear prosthesis.     

浅低温对脑干听觉诱发电位的影响

目的　观察浅低温对神经外科麻醉病人脑干听觉诱发电位 (BAEP)的影响。方法　ASAⅠ～Ⅱ级无明显听力障碍的择期神经外科手术病人 1 2例 ,在麻醉诱导插管后通过调温床给予浅低温治疗。在降温前及体温达 34℃时各记录一次BAEP ,比较降温前后Ⅴ波绝对潜伏期及Ⅰ Ⅴ波间潜伏期变化。结果　麻醉诱导后病人体温为 (35 9± 0 3)℃ ,Ⅴ波绝对潜伏期为 (6 0 0± 0 57)毫秒 ,Ⅰ Ⅴ波间潜伏期为 (4 52± 0 48)毫秒 ;降温至 34℃时 ,Ⅴ波绝对潜伏期为 (6 31± 0 36)毫秒 ,Ⅰ Ⅴ波间潜伏期为 (4 73± 0 46)毫秒。降温后Ⅴ波绝对潜伏期及Ⅰ Ⅴ波间潜伏期均有延长趋势。结论　临床上体温降低 1～ 2℃对BAEP无明显影响     

Effects of cerebellar retractions on the cochlear nerve: An experimental study on rhesus monkeys

Summary Cerebellar retractions were performed in the cerebellopontine (CP) angle of rhesus monkeys to study the relationship between changes in brainstem auditory evoked potentials (BAEP) and/or compound action potentials (CAP) from the cochlear nerve, and morphological changes in the cochlear nerve in order to investigate the nature of cochlear nerve injuries caused by this surgical procedure. The changes in the BAEP and/or CAP from the cochlear nerve that were seen during cerebellar retraction were similar to those seen in human patients during operation. After completion of each experiment the temporal bones were prepared for histological examination.Hemorrhages often developed at the fundus of the internal auditory canal as a direct result of cerebellar retraction. These hemorrhages were located at the area cribrosa, where the branches of the internal auditory artery penetrate the cribriform plate. As the hemorrhages appeared to be due to avulsion rupture of these branches, they were considered to be the probable cause of the sudden loss of all the components of the auditory responses. The cochlear nerve fibers, especially those at the basal turn of the cochlea, avulsed simultaneously at the area cribrosa in most cases.     

Evaluating Auditory Pathway by Electrical Auditory Middle Latency Response and Postoperative Hearing Rehabilitation

ABSTRACT

Objective: To establish an effective detection method to evaluate auditory pathway in patients by electrical evoked middle latency response (EMLR) before artificial cochlear implantation, and to analyze the relationship between postoperative hearing rehabilitation and auditory cortex functions. Methods: Twenty-three patients with artificial cochlear implant were recruited. EMLR was measured after adjusting the depth of anesthesia. The electrical auditory brainstem response (EABR) mode with monopolar stimulation and two-phase alternating current square waves was selected. The parameters of EMLR waveforms were recorded by the EABR measurement system. Nerve response telemetry (NRT) was examined by measuring threshold level (T value) and comfortable level (C value) 1 month after power-on, and hearing and speech development was followed up 12 months later.Results: The detection rate of EMLR was 95.65%. The waveforms of EMLR were comparable to those of auditory middle latency response (AMLR), showing decreased latency and interval but similar amplitude. The induction rate of NRT was 69.23%, which was much lower than that of EMLR. The EMLR thresholds were significantly correlated to the T and C values, and were comparable to the T values numerically. The Spearman's r value between EMLR waveforms and CAP scores after using the cochlear implant for 12 months was 0.673 (P < 0.01). Conclusion: An effective detection method to measure EMLR before artificial cochlear implant was established. The thresholds of EMLR were lower than those of NRT. The method can be useful for objective evaluation of auditory cortex functions and postoperative hearing rehabilitation.     

The effectiveness of pulse oximetry sonification enhanced with tremolo and brightness for distinguishing clinically important oxygen saturation ranges: a laboratory study

Our study examined the effectiveness of pulse oximetry sonification enhanced with acoustic tremolo and brightness to help listeners differentiate clinically relevant oxygen saturation ranges. In a series of trials lasting 30 s each, 76 undergraduate participants identified final oxygen saturation range (Target: 100% to 97%; Low: 96% to 90%; Critical: 89% and below), and detected threshold transitions into and out of the target range using conventional sonification (n = 38) or enhanced sonification (n = 38). Median (IQR [range]) accuracy for range identification with the conventional sonification was 80 (70–85 [45–95])%, whereas with the enhanced sonification it was 100 (99–100 [80–100])%; p < 0.001. Accuracy for detecting threshold transitions with the conventional sonification was 60 (50–75 [30–95])%, but with the enhanced sonification it was 100 (95–100 [75–100]%; p < 0.001. Participants can identify clinically meaningful oxygen saturation ranges and detect threshold transitions more accurately with enhanced sonification than with conventional sonification.     

Auditory evoked potential index: a quantitative measure of changes in auditory evoked potentials during general anaesthesia

We describe a novel index derived from the auditory evoked potential, the auditory evoked potential index, and we compare it with latencies and amplitudes related to clinical signs of consciousness and unconsciousness. Eleven patients, scheduled for total knee replacement under spinal anaesthesia, completed the study. The initial mean (SD) value of the auditory evoked potential index was 72.5 (11.2). During the first period of unconsciousness it decreased to 39.6 (6.9) and returned to 66.8 (12.5) when patients regained consciousness. Thereafter, similar values were obtained whenever patients lost and regained consciousness. Latencies and amplitudes changed in a similar fashion. From all parameters studied, Na latencies had the greatest overlap between successive awake and asleep states. The auditory evoked potential index and Nb latencies had no overlap. The consistent changes demonstrated suggest that the auditory evoked potential index could be used as a reliable indicator of potential awareness during propofol anaesthesia instead of latencies and amplitudes.