脑干听觉诱发电位与后循环TIA及脑干梗死的相关性研究

目的:研究脑干听觉诱发电位(BAEP)与后循环短暂性脑缺血发作(TIA)及脑干梗死的相关性。方法:选取我院收治的后循环TIA患者46例作为TIA组,选取同期收治的脑干梗死患者44例作为脑干梗死组,选取同期健康体检者49例作为健康组,TIA组和脑干梗死组均在发病后1周内进行BAEP检查,健康体检者在体检时进行BAEP检查,比较3组的Ⅰ、Ⅲ、Ⅴ波的潜伏期(PL)及Ⅰ-Ⅲ、Ⅲ-Ⅴ、Ⅰ-Ⅴ波峰间的潜伏期(IPL)。结果:TIA组BAEP异常率71.74%,脑干梗死组BAEP异常率56.82%,健康组BAEP异常率24.49%,TIA组患者BAEP异常率高于健康组,差异有统计学意义(P0.05)。脑干梗死组BAEP异常率高于健康组,差异有统计学意义(P0.05)。TIA组患者PL的Ⅰ、Ⅲ、Ⅴ水平均高于健康组,差异有统计学意义(P0.05)。TIA组患者IPL的Ⅰ-Ⅲ、Ⅲ-Ⅴ、Ⅰ-Ⅴ水平均高于健康组,差异有统计学意义(P0.05)。脑干梗死组患者PL的Ⅰ、Ⅲ、Ⅴ水平均高于健康组,差异有统计学意义(P0.05)。脑干梗死组患者IPL的Ⅰ-Ⅲ、Ⅲ-Ⅴ、Ⅰ-Ⅴ水平均高于健康组,差异有统计学意义(P0.05)。脑干梗死组患者IPL与PL均明显高于TIA组(P0.05)。结论:BAEP与后循环TIA及脑干梗死存在相关性,并且较为敏感,是优秀的诊断方法之一。     

Clinical correlates of brain-stem auditory evoked potential variables in multiple sclerosis. Relation to click polarity

The correlations between clinical signs and BAEP latency, amplitude and dispersion variables were investigated in 98 multiple sclerosis patients. A new dispersion variable, the wave IV–V “shape ratio” (SR IV–V), correlated most strongly with brain-stem signs (i.e., nystagmus). Severely reduced wave IV–V amplitude was frequently found in patients with vertical nystagmus or internuclear ophthalmoplegia, and interpeak latency (IPL) III–V correlated most strongly with cerebellar dysfunction (i.e., ataxia). The results may reflect different localizing ability among the various BAEP variables.The association between ataxia and increased IPL III–V was significantly stronger for BAEP to C clicks than to R clicks. Patients with abnormal BAEPs to one polarity (C or R) but not to the other, had significantly more clinical dysfunction than patients with normal BAEPs to both C and R clicks. Hence, C vs. R discordance may be interpreted to indicate possible brain-stem dysfunction.     

Brain-stem monitoring. II. Preterminal BAEP changes observed until brain death in deeply comatose patients

Preterminal BAEP changes were studied until brain death in 8 head-injured patients out of a series of 38 comas monitored by means of a system allowing high-rate sequential recording. Two different modalities of BAEP degradation were disclosed: (1) simultaneous latency increase of all components associated with a decrease of cerebral perfusion pressure (CPP), consistent with ongoing ischaemia of the posterior fossa; (2) deterioration of brain-stem components (waves III–V) with preserved or even enhanced wave I. The latter pattern was not consistently associated with any haemodynamic change and might be related to mechanical factors causing rostro-caudal deterioration of brain-stem function. The time course of BAEP degradation ranged from a few minutes to more than 10 h. In the case of slow preterminal evolution definitely pathological trends were identified even when individual BAEPs were still within normal limits. Such trends would have remained unnoticed in single BAEP records. Hypothermia and anaesthetic drugs were found to induce falsely alarming BAEP changes very similar to those seen during preterminal evolution. Our results suggest that continuous brain-stem monitoring could be helpful for management of comatose head-injured patients.     

The effect of click rate on latency and interpeak interval of the brain-stem auditory evoked potentials in children from birth to 6 years

Latency and interpeak interval of the brain-stem auditory evoked potentials at different click rates were measured in 80 healthy children from birth to 6 years, and 21 adults. Clicks were presented at 10, 30, 50, 70 and 90/sec, and 70, 40 and 20 db HL. At high stimulus intensity (70 dB SL), all latencies of waves I, III and V and the I–V, I–III and III–V intervals showed a progressive prolongation with increasing repetition rate. The latency- and the interval-rate functions were similar for all age groups but their slopes were slightly steeper in younger than in older. As click rate increased from 10/sec to 90/sec, the latencies of waves I, III and V at different age groups were prolonged by 4–10%, 9–13% and 12–15% respectively, and the intervals of I–V, I–III and III–V were prolonged by 15–16%, 8–16% and 14–24% respectively. The mean increments of wave V latency and I–V interval in different age groups were 0.404–0.575 and 0.332–0.526 msec respectively with increasing click rate from 10 to 50/sec, and 0.697–1.009 and 0.629–0.776 msec respectively with increasing click rate from 10 to 90/sec. The younger the age the larger the absolute increments for all these BAEP parameters, but the increasing rates for a BAEP measure were similar among different age groups, exhibiting no age-dependent differences. The III–V/I–III interval ration in most age groups was increased by 3–10% with increasing click rate from 10 to 90/sec, suggesting that the III–V interval was affected by stimulus rate slightly more than I–III interval.At moderate (40 dB HL) and low (20 dB SL) intensity, all waves and intervals showed similar latency- and interval-rate functions to those at high intensity. This demonstrates that the shifting latencies and interpeak intervals with increasing click rate appeared to be independent of the stimulus intensities.     

Age- and sex-related differences in brainstem auditory evoked potentials in secondary school students living in Northern European Russia

Brainstem auditory evoked potentials (BAEPs) were studied in 46 1st- to 11th-year students (22 boys and 24 girls) of a rural secondary school in Arkhangel’sk oblast. The objective of this work was to study age- and sex-related differences in BAEP characteristics in children and adolescents, living in the North and assess the BAEP characteristics as compared to reference values. In all three age groups of students, interpeak intervals I–III, III–V, and I–V characterizing the peripheral and central conduction times were shorter in girls than in boys. Interpeak interval III–V tended to increase with age only in boys (at puberty), with a significant increase in the latencies of waves I, III, and V. The BAEP characteristics in the subjects examined included a shorter peak latency and a greater amplitude of wave I (except senior students), relatively prolonged interpeak interval I–III, and more pronounced sex-related differences in BAEPs, especially at puberty. These findings show that it is necessary to revise regional reference values for BAEPs, differentiated by sex and age, including at puberty.     

Effects of cocaine on the brain-stem auditory evoked potential in the Long-Evans rat

The present study examined the effects of an acute psychoactive dose of cocaine hydrochloride (HCl) in the rat, using the brain-stem auditory potential (BAEP) as an objective, quantitative measure of this substance's effects on brain and auditory electrophysiology. The animals were 8 adult Long-Evans rats (4 female, 4 male). BAEPs were recorded from skull screw electrodes during a baseline period as well as 30–90 min after cocaine HCl treatment (10 mg/kg, i.p.). Normothermia was maintained to control for possible temperature-related effects. Cocaine's effects on the BAEP were examined over a broad range of stimulus intensities (intensity profiles) and repetition rates (rate profiles). Cocaine prolonged latencies of several BAEP components at low stimulus intensities and shortened these latencies at high stimulus intensities. The average BAEP threshold was alos increased by cocaine treatment. These results were not strong, but were suggestive of a recruitment type change in auditory function. Cocaine treatment had no convincing effects on the BAEP as a function of stimulus repetition rate.     

Evoked potential findings in Behçet's disease. Brain-stem auditory,visual, and somatosensory evoked potentials in 44 patients

We studied 54 patients with Behçet's disease, 41 males and 13 females, mean age 28 years. Forty-four patients had auditory brain-stem evoked potential (BAEP) recordings, 39 had pattern reversal visual evoked potentials (VEP), 27 had median nerve somatosensory evoked potential (SEP) recordings, and 25 tibial nerve SEPs. BAEPs were abnormal in 16 patients (52%) with neurological manifestations and in 4 (31%) without, because of decreased amplitude of wave V, prolonged I–III or III–V interpeak latencies, or uncertain/absent waves III and/or V. Eleven patients (40%) with neurological symptoms and 3 patients (25%) without, had abnormal VEPs. Absent potentials, decreased amplitude, with or without prolonged P100 latency, were found in 75% of the cases, the rest had prolonged P100 latency only. Median SEPs were abnormal in 8 patients (38%) with neurological manifestations. Four patients (21%) had abnormal tibial SEPs. Decreased amplitude with or without mild slowing in central conduction was the predominant SEP abnormality. SEPs were normal in all patients without neurological symptoms. In total, 84% of patients with, and 38% of patients without, neurological symptoms had abnormalities of one or more EP modality.When used cautiously, EP studies in Behçet's disease might be helpful to separate neuro-Behçet from other disorders with similar symptomatology, to disclose subclinical CNS involvement, to evaluate and monitor CNS disease activity, and to provide objective measures of treatment response.     

Monitoring therapeutic efficacy of decompressive craniotomy in space occupying cerebellar infarcts using brain-stem auditory evoked potentials

Brain-stem auditory evoked potentials (BAEPs) have been used to gauge effects of brain-stem dysfunction in humans and animal models. The purpose of this study was to evaluate the usefulness of BAEP in monitoring patients undergoing decompressive surgery of the posterior fossa for space occupying cerebellar infarcts.We report on serial BAEP recordings in 11 comatose patients with space occupying cerebellar infarcts undergoing decompressive craniotomy. BAEP studies were performed within 12 h after admission, 24 h following surgery and prior to extubation. BAEP signals were analyzed using latency determination and cross-correlation.Following surgery, 9 patients regained consciousness; 2 patients persisted in a comatose state and died subsequently.BAEP interpeak latency (IPL) I-V assessed prior to surgery exceeded normal values in all patients in whom it could be reliably measured (N = 9). Following decompressive surgery BAEP wave I-V IPL normalized in 5 patients, but remained prolonged despite dramtic clinical improvement in 4 patients. We prospectively computed the coefficient of cross-correlation (MCC) of combined ipsilateral BAEP trials after right and left ear stimulation. In all patients increasing MCC was associated with clinical improvement. Unchanging or decreasing MCC indicated poor outcome.We conclude that serial BAEP studies are an appropriate perioperative monitoring modality in patients with space occupying cerebellar infarcts undergoing decompressive surgery of the posterior fossa.Our study suggests advantages of cross-correlation analysis as an objective signal processing strategy; relevant information can be extracted even if BAEP wave discrimination is impossible due to severe brain-stem dysfunction.     

The interaction between sex and click polarity in brain-stem auditory potentials evoked from control subjects of Oriental and Caucasian origin

Brain-stem auditory evoked potentials (BAEPs) were performed on 30 male and 30 female young normal Oriental subjects, using both condensation and rarefaction stimulation. The effects of sex and click polarity on the BAEP latencies and amplitudes were studied. Females had shorter absolute and interpeak latencies and higher absolute amplitudes than the males. These sex-related BAEP differences were independent of the click polarity. Rarefaction clicks produced shorter wave I latency and longer I–III interpeak latency, but the differences were significant in the female only. The polarity-related BAEP amplitude differences were essentially independent of the sex. BAEPs performed on 60 sex- and age-matched young Caucasian subjects produced similar results. The importance of establishing control BAEP values according to the sex and click polarity is emphasised.     

Chronic effects of phenytoin on brain-stem auditory evoked potentials in man

The effects of phenytoin (PHT) on brain-stem auditory evoked potentials (BAEPs) were studied in 65 epileptic patients who received long-term PHT monotherapy at therapeutic and supra-therapeutic levels with no clinical evidence of brain-stem toxicity. Abnormal BAEPs were found in 7.5% and 33.3% of patients with therapeutic and supra-therapeutic PHT levels respectively. Serum PHT levels had a trend towards a positive relationship with the I–V interpeak latency (IPL), and a significant negative relationship with the amplitudes of waves I and V. at supra-therapeutic levels, both I–V and I–III IPLs were significantly prolonged while at therapeutic evels onl I–III IPLs were prolonged. The absolute latency of wave I was prolonged in both the therapeutic and the supra-therapeutic groups. These results suggest that PHT acts both peripherally on either the auditory nerve or the cochlea, and centrally on brain-stem conduction.     

BAEP subcomponents and wave form — relation to click phase and stimulus rate

The latency distributions of normal brain-stem auditory evoked potential (BAEP) components elicited by condensation (C) and rarefaction (R) clicks at 10 and 50 Hz were found to be double- or multi-peaked for II (10 and 50 Hz), III (50 Hz), IV (10 and 50 Hz) and V (10 Hz). A bifid component III was found in 3.5% (10 Hz) and 7.4% (50 Hz) of BAEPs. A bifid II and triple IV/V configuration were occasionally noted. The prevalences of the different IV/V complex configurations were significantly dependent upon click phase and rate. These results suggest that several subcomponent might participate in the generation of the single BAEP components and that a single generator may contribute to different BAEP components in different subjects.Early subcomponents between I and II (Ib) were found in 13% of 10 Hz BAEPs and 27% of 50 Hz BAEPs (P = 0.002) and the latency distribution of Ib seemed to be bimodal. Ib/I relative amplitude frequently increased with 50 Hz stimulation.We suggest that the generator of Ib is partially cochlear (CM) and partially neural (equivalent to N2 of the ECochG-AP) in origin.The existence of subcomponents must be recognized in clinical use of BAEPs both to avoid misinterpretation and to decrease the normal variability in monophasic click evoked BAEP studies.     

Binaural interaction and the effects of stimulus intensity and repetition rate in human auditory brain-stem

Binaural interaction (BI) components in brain-stem auditory evoked potential (BAEP) and their changes with stimulus intensity and repetition rate were examined in human adult. Seven BI components were identified, which occurred between the latency range of 5 and 11 ms and coincided consistently with the latency range of BAEP waves IV–VII. Waves DV and DVII, occurring at the downslopes of BAEP-waves V and VII, respectively, were the two most prominent and reproducible BI components. Wave DVII existed consistently at high, moderate and, in most cases, low stimulus intensities, suggesting that this component is neurogenic although acoustic cross-talk may account for a part of its waveform at high stimulus intensities. The latencies of all BI components increased as a function of decreasing stimulus intensity, while the interpeak intervals, especially DV–DVII, were essentially constant at different intensity levels. The amplitudes of BI components decreased slightly with decreasing intensity. As click repetition rate increased, BI wave latencies and interpeak intervals increased slightly and amplitudes decreased slightly. When repetition rate increased to above 20/s, BI components became poorly differentiated. Lower repetition rates, e.g. 10/s, are therefore preferred for routine derivation of the BI. The changes in the latency and amplitude of BI components with stimulus intensity and repetition rate were associated or concomitant with those of the corresponding BAEP components in monaural and binaural potentials. In view of the concomitant relationship between BI and BAEP latency, we designate BI components in association with the corresponding BAEP components.     

Hepatic glutathione content in patients with alcoholic and non alcoholic liver diseases

Reduced and oxidized hepatic glutathione was evaluated during alcoholic and non alcoholic liver injury. We studied 35 chronic alcoholics, 20 patients with non alcoholic liver diseases, 15 control subjects. Hepatic glutathione was measured in liver biopsies and correlated with histology and laboratory tests. Alcoholic and non alcoholic patients exhibited a significant decrease of hepatic glutathione compared to control subjects (controls: 4.14 +/- 0.1 mumol/g liver; alcoholics: 2.55 +/- 0.1, p less than 0.001; non alcoholics 2.77 +/- 0.1, p less than 0.001). Oxidized glutathione was significantly higher in the two groups of patients compared to controls (controls: 4.4 +/- 0.2% of total; alcoholics 8.2 +/- 0.3, p less than 0.001; non alcoholics: 8.5 +/- 0.8, p less than 0.001). The decreased hepatic glutathione levels in patients with alcoholic and non alcoholic liver diseases may represent a contributing factor of liver injury and may enhance the risk of toxicity in these patients.     

Brainstem auditory evoked potentials in the fetal sheep, in utero

We studied brainstem auditory evoked potentials (BAEPs) in 8 fetal sheep in utero, ranging in gestational age from 105 to 142 days gestation (normal term 147 days). We could not elicit BAEPs prior to 117 days of gestation. After this age rapid maturation was seen, with three discernible peaks observed prior to 120 days and five peaks after 120 days. A significant (P less than 0.05) gestational age related fall in peak latencies and interpeak latencies was observed. The rate of stimulus presentation that could be tolerated without significant changes in wavepeak latency or amplitude also increased with advancing gestational age. In older fetuses (greater than 125 days), where a differentiated electrocorticogram (ECOG) was observed, differences were seen in latency and amplitude of several of the BAEP wavepeaks dependent upon the state. In high voltage ECOG states the amplitudes of wave IV and V were significantly (P less than 0.05) greater than in the low voltage ECOG state and the latencies of wave I, II and V were significantly (P less than 0.05) longer in low as compared to high voltage ECOG state. The BAEP, being obtainable over very short periods of time, appears to provide a useful indice of neural maturation for the sheep fetus in utero.     

Age-dependent amplitude variation of brain-stem auditory evoked potentials

Normative amplitude values of brain-stem auditory evoked potential (BAEP) components are given for normally hearing subjects at 1, 10, 30, 50 and 70 years of age, with an intragroup age variation of only ±6 months. Under these circumstances amplitude standard deviations decreased to less than 20% of the mean values. In contrast with the reduced evolution of latency with age, BAEP amplitude (for components I–V) undergoes a greater oscillation during ontogeny. With the exception of component I, it increased markedly from 1 year to 10 years of age and decreased thereafter constantly up to 50 years, with a mean rate of 10 nV yearly. The decrease slowed down between 50 and 70 years. The amplitude differences between the subgroups are highly significant statistically (P < 0.01). Possible reasons for these changes are discussed.     

Temperature-dependent hysteresis in somatosensory and auditory evoked potentials

Fourteen adult patients undergoing open heart surgery under induced hypothermia had median nerve, short-latency somatosensory evoked potentials (SSEPs) recorded during cooling (from 36°C to 19°C) and subsequent rewarming. Similar data on another group of patients who had brain-stem auditory evoked potentials (BAEPs) were also analyzed. Hypothermia produced increased latencies of the major SSEP and BAEP components and the latencies returned to normal with subsequent warming. The temperature-latency relationship during the cooling phase was significantly different from that during the warming phase. For SSEP components the temperature-latency relationship was linear during cooling and curvilinear during warming, whereas for BAEP it was curvilinear both during cooling and warming. Furthermore, the regression curves were different during the two phases of temperature manipulation, particularly for temperatures below 30°C both for SSEP and BAEP components. At the onset of warming there was an initial exaggerated warming response on the evoked potential (EP) latencies and amplitude of the EP components. The temperature-latency regression curves were uniformly less steep during the warming phase compared to those during cooling. These findings suggest the existence of hysteresis in the relationship between temperature and EP latencies. The latencies at a given temperature below 30°C depend on whether that temperature is reached during cooling or during warming.     

A parametric scale for BAEP latencies in multiple sclerosis

A parametric scale for measuring BAEP latencies is set forth here for use in multiple sclerosis (MS) therapeutic trials and similar longitudinal studies. Derived constants are used to create a synthetic I–V interpeak interval, needed for cases where V (or other waves) are absent. Transitional peaks (peaks on the verge of disappearing) were studied in MS patients and used to determine appropriate values for the weighting constants. The resulting scale or index makes use of latencies to whichever peaks are still present. In theory such a scale is more sensitive to small changes than either a simple ordinal scale of which peaks remain or a parametric scale of I–V interpeak intervals excluding the 25–40% of MS records with absent wave V. To test this synthetic I–V index in practice, we studied it in 100 MS patients entering a therapeutic trial. It was found to correlate appropriately with patients' history, physical examination, and clinical scales at entry into the trial. Parametric statistical analysis of the derived scale was able to show a statistically significant drug effect during the therapeutic trial, whereas 3 other data analysis techniques showed at best a trend that did not quite reach significance.     

解酒护肝饮解酒及对急慢酒精性肝损伤的保护作用

为了评价解酒护肝饮解酒效果及其对急、慢性酒精性肝损伤保护作用机制,本研究通过建立醉酒模型,确定致醉剂量;通过醉酒睡眠实验比较解酒护肝饮解酒特性;通过测定醉酒小鼠血乙醇含量的变化,研究解酒护肝饮对乙醇代谢的影响;通过建立急慢性酒精性肝损伤模型,测定AST、ALT、SOD活性,GSH、MDA水平,HE染色切片观察肝组织形态学的变化。研究发现小鼠最佳致醉剂量为11 m L/kg;与模型组比较,解酒护肝饮高(HD)、中剂量组(MD)均可延长醉酒时间、缩短醒酒时间(p<0.05),高、中剂量组可降低酒精灌胃后2 h、3 h时间点血乙醇含量(p<0.05);与模型组比较,急慢性酒精肝损伤模型各剂量组均能显著降低血清AST、ALT活性(p<0.05),急性酒精性肝损伤模型中,各剂量组肝组织SOD、GSH水平上升(p<0.05),MDA水平下降(p<0.05),而在慢性酒精性肝损伤模型肝组织中,低剂量组(LD)的SOD、GSH及MDA水平没有统计学差异;病理切片观察可见,急慢性酒精肝损伤模型高、中、低剂量组均能显著改善肝组织因乙醇而导致的肝损伤,并且高、中剂量组效果较好。本研究表明解酒护肝饮可显著延长醉酒时间,缩短醒酒时间,降低血乙醇的含量,对酒精诱导的肝损伤有较好的保护作用。     

Diagnostic role of brain-stem auditory evoked potentials in neurobrucellosis

Evoked potential audiometry and brain-stem auditory evoked potentials were evaluated in 15 patients with systemic brucellosis in whom brucella meningitis was suspected clinically. In 8 patients cerebrospinal fluid (CSF) was abnormal with high brucella titre, and evoked potentials were abnormal in all of them. In 7 patients the CSF was normal and evoked potentials were also normal. Brain-stem auditory evoked potential abnormalities were categorised into 4 types: (1) abnormal wave I, (2) abnormal wave V, both irreversible, (3) prolonged I–III interpeak latencies, and (4) prolonged I–V interpeak latencies, both reversible. These findings are of important diagnostic value and correlate well with the clinical features, aetiopathogenesis and final outcome.     

T cells from patients with chronic liver diseases: abnormalities in PHA-induced expression of HLA class II antigens and in autologous mixed-lymphocyte reactions

The expression of HLA Class II antigens by resting and phytohemagglutinin (PHA)-activated T cells and their functional properties in autologous mixed-lymphocyte reactions (MLR) were investigated in patients with chronic active hepatitis, with alcoholic cirrhosis, and with primary biliary cirrhosis. In all groups of patients the percentage of resting T cells expressing HLA Class II antigens was significantly higher than that in controls. The percentage of T cells which acquired HLA Class II antigens following PHA stimulation was reduced in patients with chronic active hepatitis, serum hepatitis B surface antigen (HBsAg) positive, and in those with alcoholic cirrhosis, HBsAg negative, although the level of [3H] thymidine incorporation was within normal limits. The degree of proliferation in autologous MLR with PHA-T cells was significantly reduced in patients with chronic active hepatitis, HBsAb positive, and in those with alcoholic cirrhosis, HBsAg positive. A reduced proliferation was also detected in autologous MLR with non-T cells, in patients with chronic active hepatitis, HBsAg positive. The abnormalities of autologous MLR are selective, since the proliferative and stimulatory activities of cells from patients with chronic liver diseases in allogeneic MLR were within normal ranges. The immunoregulatory role of HLA Class II antigens and of autologous MLR suggests that the abnormalities we have identified may play a role in the immunological dysfunctions underlying chronic liver diseases.