前庭阵发症脑干听觉诱发电位的特点

目的探讨前庭阵发症(VP)脑干听觉诱发电位(BAEP)的特点。方法对51例VP患者的BAEP结果进行回顾性分析。结果 BAEP异常者40例,异常率为78.4%。与Ⅰ-Ⅲ波峰间期正常的患者相比,Ⅰ-Ⅲ波峰间期延长的患者男性比例高(χ2=4.763,P=0.029),病程显著延长(t=2.469,P=0.021),而平均年龄差异无统计学意义。与Ⅲ-Ⅴ波峰间期正常的患者比较,Ⅲ-Ⅴ波峰间期延长的患者男性比例、平均病程、平均年龄差异均无统计学意义。与Ⅰ-Ⅲ波峰间期耳间差正常的患者比较,Ⅰ-Ⅲ波峰间期耳间差延长的患者病程相对较长(P=0.055),男性有增多趋势(P=0.058),但差异无统计学意义。结论 VP患者BAEP异常以Ⅰ-Ⅲ波峰间期延长为主,且以男性更多见。病程越长,蜗神经越易受累。     

Evaluation of patients with multiple sclerosis by evoked potentials and magnetic resonance imaging: a comparative study

We compared the diagnostic usefulness of evoked potential (EP) studies and magnetic resonance imaging (MRI) in the evaluation of 27 patients with definite or probable multiple sclerosis (MS). MRI scans demonstrated multiple lesions in 21 patients whereas EP studies showed multiple abnormalities in 14 patients (4 of whom had only somatosensory EP abnormalities). Eighteen patients had similar MRI and EP results (e.g., normal or multiple abnormalities), 8 had multiple abnormalities shown by MRI but normal or single-modality abnormal EPs, and 1 had multiple abnormal EPs but a normal MRI scan. There was no significant difference in the sensitivity of the two techniques in detecting multiple lesions in the patients with definite MS, whereas among those with probable MS, MRI had a significantly higher yield. Seventeen patients showed clinical evidence of posterior fossa involvement, 6 patients had abnormal brainstem auditory evoked potentials (BAEPs), and 4 patients had areas of increased signal intensity revealed by MRI of the brainstem. There was no clinical evidence of brainstem involvement in 2 patients with BAEP abnormalities, 2 with an abnormal posterior fossa shown by MRI, and one patient with abnormalities shown by both BAEP and MRI. We conclude that MRI is more sensitive in detecting multiple lesions than are multimodality EP studies, but that BAEP assessment may be slightly more sensitive than MRI in detecting brainstem lesions.     

Absence of rate-dependent BAEP P5 latency changes in patients with definite multiple sclerosis: possible physiological mechanisms

Brain-stem auditory evoked potential (BAEP) rate studies have been incorporated into evoked potential protocols in an attempt to identify demyelinating lesions. A group of 9 patients with clinically definite MS are described who showed abnormal BAEP P1-P5 interwave latencies at slow repetition rates and failed to demonstrate a significant enhancement of this abnormality following rapid click presentation rates. The lack of rate-dependent P5 latency changes has been hypothesized to represent a less severe form of axonal demyelination. Thus, it may be possible to subclassify or subgroup patients with evidence of brain-stem demyelination based on the presence or absence of BAEP rate-dependent abnormalities.     

Effects of stimulus repetition rate on slow and fast components of auditory brain-stem responses

Effects of stimulus repetition rate on the slow and fast components of the auditory brain-stem response (ABR) were investigated in 10 adult subjects with normal hearing. The ABRs were recorded with click stimuli at repetition rates of 8, 13.3, 23.8, 40 and 90.9/sec and at an intensity level of 55 dB nHL. Power spectral analysis of the averaged responses was performed. Then the responses were divided into a slow component (0-400 Hz) and a fast component (400-1500 Hz) by using digital filtering technique. The magnitude of the slow component was little affected with increasing stimulus rate from 8/sec to 90.9/sec, while successive waves of the fast component, including wave V, decreased in amplitude as stimulus rate was increased. The latency of the slow component and each wave of the fast component was prolonged with increasing click rates. The shift of latency became longer in the later waves than in the earlier waves.     

Relation of optic myelitis (OM) and multiple sclerosis (MS)

Brainstem auditory evoked potentials (BAEP) were studied on 38 optic myelitis (OM) and 16 of myelopathy with definite abnormal VEP. Forty-two normal subjects were studied for comparison. The results showed that BAEP were abnormal in 42% of the OM and 38% of the latter myelopathy groups. Among the abnormal BAEP 82% showed V wave abnormality, 32% prolongation in I-III or III-V interpeak latency or absence of III wave, and 59% with unilateral lesions. These findings would imply that the lesions were mostly on the white matter and small and localized in character which was compatible with the pathology of MS. 41% of BAEP abnormality in these two groups showed a lesion would be in the brainstem in almost half of these two types of disorders. OM would be most likely a clinical variant type of MS and not a unique disease.     

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.(ABSTRACT TRUNCATED AT 250 WORDS)     

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 evoked 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 also 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.     

脑干听觉诱发电位在听阈正常的语言发育迟缓患儿中的意义

目的 探讨脑干听觉诱发电位（BAEP）在听阈正常而语言发育迟缓患儿中的变化规律及应用价值.方法 分析100例听阈正常而语言发育迟缓患儿BAEP的变化规律;按年龄分组比较两个年龄段之间各波的延长时间.结果 （1）BAEP正常10例,异常90例,BAEP表现为Ⅰ、Ⅴ波潜伏期（PL）延长,Ⅲ~Ⅴ、Ⅰ~Ⅴ波峰间期（IPL）延长;（2）随着年龄增长,Ⅴ波PL与Ⅲ~Ⅴ波IPL延长时间越长.结论 Ⅰ波、Ⅴ波延长对早期诊断听阈正常而语言发育迟缓患儿具有一定的意义,说明即使听阈正常也可能存在听觉传导通路异常,且随着年龄增加,脑干上段受损越严重.     

Visual, early auditory and somatosensory evoked potentials in multiple sclerosis (917 cases)

Visual (VEP), brainstem auditory (BAEP) and somatosensory (SEP) evoked potentials were recorded over a 6 year period in 917 patients with or suspected of multiple sclerosis according to Mc Alpine's criteria. Evoked potentials provided information of diagnostic relevance in detecting clinically unsuspected lesions (spatial dissemination). They also gave valuable informations in patients with atypical or borderline clinical features. When abnormal, VEP indicated clinically silent lesions in 45.1 p. 100 of patients with definite MS, 66 p. 100 of those with probable MS and 78 p. 100 of the possible MS. Less than 15 p. 100 of SEP and/or BAEP abnormalities were found in 83 patients with a simple or recurring retrobulbar optic neuritis. Thirteen patients with acute transverse myelopathy and no prior history of neurological disease were studied. All had normal visual and brainstem auditory evoked potentials. Abnormal VEPs helped to the clinical assessment of 88 patients with progressive spastic paraparesis 46,6 p. 100 of whom had abnormal VEPs demonstrating disseminated lesions and 36,1 p. 100 had abnormal BAEPs. The frequency of the various types of VEP, BAEP and SEP abnormalities was studied as well as their course on repeated recordings. Results of multivariate analysis are given. It was found that the longer the time interval between the first MS relapse and the evoked potential recording, the higher the incidence of abnormalities. The incidence of evoked potentials abnormalities was lower in patients with normal CSF and higher in patients with inflammatory CSF. The abnormalities were more frequent when patients had clinical evidence of lesions of the sensory pathways explored by the tests.     

Prolonged brainstem transmission time in autism

Brainstem auditory evoked potentials (BAEPs) to clicks presented monaurally were gathered for 16 institutionalized children with a prior diagnosis of autism and with no hearing loss as tested by standard audiometry. Twenty age-matched normal children served as controls. Brainstem transmission time, defined as BAEP interpeak I-V latency, was prolonged significantly on the average in the autistic sample on both left and right sides. Individually, BAEPs for 9 of the 16 autistic children (or 56%) on whom some electrophysiological data were gathered were classified as abnormal when compared to the norms established in the control group. The most common BAEP abnormality was a prolonged interpeak III-V latency on the left side.     

Altered peripheral and brainstem auditory function in aged rats

A technique for conducting free-field brainstem auditory evoked potential (BAEP) audiometry in unanesthetized, unrestrained rats revealed a non-recruiting 18 dB elevation of click threshold in aged rats. BAEPs were first recorded in young and aged rats to clicks of equal intensity (80 dB SPL). Compared to the young group, aged animals exhibited longer wave I and wave IV latencies with no difference seen in the I–IV central conduction time. The prominent negative wave (No) following wave IV was also delayed and the I-No and IV-No conduction times increased in the aged group. When BAEPs were recorded to clicks with intensities adjusted to 35 dB above individual threshold, no differences in wave I or wave IV latencies or in the I–IV central conduction time were found between groups. However, the No component was delayed and the I-No and IV-No conduction times remained prolonged in the aged group. The results suggest that in addition to changes in peripheral auditory structures, changes in the rostal auditory brainstem accompany age-related hearing loss in rats.     

Neurophysiological and neuro-otological study of homozygous beta-thalassemia under long-term desferrioxamine (DFO) treatment

This report presents data on visual evoked potentials (VEPs) and brainstem auditory evoked potentials (BAEPs), as well as neurologic, ophthalmologic and otologic assessments performed on 120 patients with beta-thalassemia major undergoing long-term DFO treatment. A total of 32 patients showed abnormal VEPs and 14 abnormal BAEPs; seven had both VEP and BAEP abnormalities; 12 had sensorineural hearing loss (SNHL); 18 had conductive hearing loss, while 14 showed a combination of SNHL and conductive hearing loss. After DFO administration was modified (taking in consideration the serum ferritin levels) patients with abnormal findings were retested. The values of 15 patients of 23 who underwent VEP examinations had been normalized. Eleven of 15 who repeated the BAEP test had also gained normal values. The audiogram had not returned to normal in any patient with SNHL. In a second repetition of the examinations, no change was observed. It is concluded that in a great percentage of thalassemics at least one of the above examinations shows abnormal values. These abnormalities are mostly reversible, and probably reflect a dysfunction of the visual or auditory system, due either to DFO neurotoxicity or to iron overload or both.     

Myelination patterns on magnetic resonance of children with developmental delay.

Magnetic resonance (MR) imaging was performed in 30 children with unexplained developmental delay who had associated neurological abnormalities such as seizures, spasticity, hypotonia, ataxia or poor vision. No child had a history of regression, preterm birth or neonatal cerebral injury. CT scans were performed before MR in all cases and were either normal or showed only mild atrophy. At least two MR sequences were obtained for all patients. Nine children had delayed or absent myelination on MR, one had patchy white-matter abnormalities, and in one patient myelination was topographically normal, but of inappropriately low signal intensity. MR was abnormal in six of seven children who had abnormal brainstem auditory evoked potentials (BAEP), and was normal in nine of 11 patients who had a normal BAEP. MR may have a useful r?le in demonstrating abnormal white-matter maturation in children with unexplained neurodevelopmental delay, particularly when abnormalities are found on BAEP studies.     

Diagnostic value of electroencephalography and brainstem auditory evoked potentials in dizziness

Electroencephalogram (EEG) and brainstem auditory evoked potentials (BAEP) were recorded from 142 dizzy patients. The results were compared with those obtained by other neurological examinations of the same patients. Thirty-three percent (N = 44) of the patients had an abnormal EEG: 21% (28) showed focal abnormality, 12% (16) irritative features, and 10% (13) generalized disturbance. There were no differences in the distribution of abnormal EEGs in different diagnostic categories of dizziness, but irritative findings were not found in the cases of peripheral vestibular or psychogenic disturbances. EEG findings in 3 patients suggested temporal epilepsy, correlating with the clinical picture. BAEPs were abnormal in 18% (N = 21) of the recordings. There were 3 cases of MS and 5 ischaemic lesions in the vertebro-basilar region. Twelve of the 13 other patients with abnormal BAEP showed evidence of CNS pathology with other methods. EEG abnormalities were mostly non-specific; however, the irritative findings suggested cerebral pathology, such as epilepsy. An abnormal BAEP offers reliable evidence for brainstem lesion and is thus a useful examination in dizziness.     

Evoked potentials in chronic n-hexane intoxication

Somatosensory, brainstem auditory and pattern-reversal visual evoked potentials (SEP, BAEP and PVEP) were studied in 5 patients with n-hexane polyneuropathy to determine if the CNS was affected. In SEPs, the median central conduction (N13-to-N20) was normal but the tibial central conduction (N22-to-P40) was delayed. The central conduction time (I-to-V interval) of the BAEP was also prolonged. However, the P100 latency of the PVEP was normal. The present data indicate that the spinal cord and the brainstem are primarily affected in chronic n-hexane intoxication.     

Long-term impairments of brain and auditory functions of children recovered from purulent meningitis

Sixty children who had recovered from purulent meningitis one to six years earlier were investigated for long-term impairment of brain and auditory function, using brainstem auditory evoked potentials(BAEP) and developmental screening tests. Neurological and/or audiological BAEP abnormalities were found in 23 per cent of the children: 15 per cent had mild brainstem impairment and 12 per cent had hearing dysfunction. Developmental screening tests were administered to 46 children, of whom 61 per cent had normal, 22 per cent questionable and 17 per cent abnormal results. The results of the BAEP significantly correlated with those of the developmental screening tests, suggesting that the neuropsychological development of children with BAEP abnormalities was significantly delayed compared with that of children without BAEP abnormalities. The characteristic finding in a neurologically abnormal BAEP was slightly depressed amplitude of wave V, and the authors suggest that this is the most sensitive BAEP measure for the assessment of brainstem function in children recovered from meningitis.     

Study of brainstem auditory evoked potentials in patients with vertebrobasilar blood supply insufficient]

Brainstem auditory evoked potentials (BAEP) were studied in 93 patients with vertebrobasilar blood supply insufficient. The result showed that the abnormal rate of BAEP was 76.3%, and the rate of abnormality in acute period was much higher than that in recovery period. The BAEP types were classified as inner, brainstem and mixed. The vertigo could be caused by the inner ear ischemia, brainstem or both of them. If there is no improvement of BAEP in long-term follow-up, it suggested that there should be the tiny infarction affecting auditory passage or subclinical blood supply insufficient in brainstem. We believe that BAEP is valuable for the diagnosis of vertebrobasilar blood supply insufficient.     

Reliability of hearing screening in high-risk neonates: Comparative study of otoacoustic emission,automated and conventional auditory brainstem response

ObjectiveTo compare the diagnostic reliability of automated transient evoked otoacoustic emissions (a-TEOAE), automated auditory brainstem response (a-ABR) and conventional brainstem auditory evoked potential (BAEP/ABR) for identification of hearing loss in high-risk neonates.MethodsTwo hundred and six neonatal intensive care unit (NICU) admitted neonates were tested pre-discharge. Follow-up included a-TEOAE in all children, repetition of a-ABR or BAEP if failed in NICU. Sensitivity and specificity were compared and correlated with auditory risk factors.ResultsBAEP had the highest sensitivity (100%) and specificity (90.8%), a-ABR the lowest (88.9% and 70.6%). A statistically significant difference in risk factors for temporary hearing loss was observed between normal and false positive a-TEOAE and BAEP, but not a-ABR outcome. Differences in specificity between a-ABR and a-TEOAE explain the pattern of ‘absent a-ABR/present a-TEOAE’ in 13.8% of ears.ConclusionsThe BAEP appears the more reliable test for hearing screening of high-risk neonates because of highest sensitivity and specificity and should be used to confirm the diagnosis of ‘auditory neuropathy’ in high-risk neonates. The reliability of a-ABR devices in critically ill neonates needs further investigation.SignificanceThis is, to our knowledge, the first attempt to compare the diagnostic reliability of a-TEOAE, a-ABR and BAEP in high-risk neonates.     

Brainstem auditory-evoked potentials studied with paired stimuli in multiple sclerosis patients

In 19 patients with definite multiple sclerosis (MS) brainstem auditory-evoked potentials (BAEP) with paired stimuli were recorded. Only hearing pathways without abnormalities in usual BAEP were examined. The latencies of wave III and wave V were significantly increased with the paired-stimulus technique (using paired-click intervals of 1.5 and 4.0 ms duration) compared to single clicks. In 4 patients (21%) paired-click BAEP latencies exceeded the critical values of normal subjects. This technique might give new possibilities in detecting minor lesions in MS patients.     

Evaluation of ipsilateral and contralateral brainstem auditory evoked potentials in multiple sclerosis patients

Brainstem auditory evoked potentials (BAEP) were recorded simultaneously between the vertex and the mastoid ipsilateral and contralateral to the ear stimulated in 30 patients with multiple sclerosis (MS) and compared with the responses in a control group of 30 normal hearing adults. The control group showed that significant latency differences exist between ipsilateral and contralateral recording. Definitions of abnormalities were based on interwave separation and the wave V amplitude ratio. No case was found among the MS patients with an abnormal contralateral but normal ipsilateral response.