Changes of brainstem auditory and somatosensory evoked

Objective: to investigate the characteristics and clinical value of evoked potentials in late infantile form of metachromatic leukodystrophy. Methods: Brainstem auditory, and somatosensory evoked potentials were recorded in 6 patients, and compared with the results of CT scan. Results: All of the 6 patients had abnormal results of BAEP and MNSEP. The main abnormal parameters in BAEP were latency prolongation in wave I, inter-peak latency prolongation in Ⅰ-Ⅲ and Ⅰ-Ⅴ. The abnormal features of MNSEP were low amplitude and absence of wave N9, inter-Peak latency prolongation in Ng-N13 and N13-N20, but no significant change of N20 amplitude. The results also revealed that abnormal changes in BAEP and MNSEP were earlier than that in CT. Conclusion: The detection of BAEP and MNSEP in late infantile form of metachromatic leukodystrophy might early reveal the abnormality of conductive function in nervous system and might be a useful method in diagnosis.     

Somatosensory and brainstem auditory evoked potential studies in nontraumatic coma

We believe that somatosensory and brainstem auditory evoked response studies help in the understanding of the dysfunction of the ascending sensory pathyways at various levels. In some patients where EEGs showed a significant contamination of muscle and background noise, the SEP studies helped to identify the level of dysfunction. The severity of the clinical condition (GCS score) correlated significantly (p = 0.003) with the prolongation of the CCT. Asymmetries in CCTs were more frequent in the stroke group than in the other groups. The presence of asymmetries in CCT in diffuse encephalopathies indicated a variable degree of dysfunction in the ascending sensory pathways, which clinically were not easily identifiable. This fact raised the possibility of either pre-existing lesion(s) or recent insult(s) such as ischemia. The presence or absence of N20 appeared to influence the duration of survival in subgroups. Some degree of difference in duration of survival was noted among the metabolic group with and without N20 potential. The subset of patients with N20 potential survived relatively longer than the group without it. A suggestion of influence was seen in the stroke group, but caution must be exercised because the absence of N20 was compatible with survival. The hypoxic group did not show any difference. A combination of prolonged interpeak EP-N13 and N13-N20 indicated a poor prognosis. A distinct absence of Wave I in BAER limited its usefulness on some occasions. A combination of abnormal interpeak III-V and abnormal CCT seemed to suggest a poor prognosis. Although death generally occurred earlier in the stroke group, age did not seem to influence the mortality in the first 10 days. Similarly, the cause of death also did not seem to influence the course in those 10 days. None of the adult patients survived.     

脑干听觉诱发电位及体感诱发电位在重型颅脑损伤患者预后评估中的作用

目的 分析探讨脑干听觉诱发电位(BAEP)及体感诱发电位(SEP)与重型颅脑损伤病人预后的关系.方法 对33 例重型颅脑损伤患者早期行BAEP 及SEP 测定并进行动态监测,同时行头颅CT 检查并记录GCS 评分.结果 BAEP 及SEP 预测预后的敏感性、特异性、准确性均较高.BAEP、SEP 异常程度低,则预后较好;异常程度高,则预后不良.结论 BAEP、SEP 可以比较准确地评估重型颅脑损伤患者的预后.     

Auditory brainstem response and somatosensory evoked potential in Machado-Joseph disease in Japanese families

To clarify physiological aspects of Machado-Joseph disease (MJD), we studied auditory brainstem response (ABR) and somatosensory evoked potential (SEP) in 17 clinically diagnosed patients with MJD aged 32-64 in Japanese families. ABR was recorded in 13 patients. In 8 patients, ABR were abnormal. In 5 patients, the latency of I wave was normal, but other waves could not be evoked. In the other 3 patients, I-III interpeak latency was prolonged. SEP was recorded in 15 patients. In SEP of median nerve, 11 patients had abnormal findings, and SEP of posterior tibial nerve revealed abnormal findings in all 15 patients. In all patients, responses from Erb's point and popliteal fossa were normal in latency, but other peaks were low in amplitude or absent, and the latency and central conduction time (CCT) were prolonged. The result of ABR indicated the involvement of the brainstem auditory pathways in MJD, and the result of SEP suggested that somatosensory pathways, particularly central pathways, would be involved in the disease process. ABR and SEP can be potential diagnostic methods for detection of subclinical abnormality in MJD patients.     

The brainstem auditory evoked potential in infants and children.

The brainstem auditory evoked potential (BAEP) is a neurophysiological study that provides functional information about the auditory system and brainstem. It provides information that is different from any other form of evaluation. This report tries to summarize technical and clinical information that will make the BAEP more meaningful for the practicing technologist and clinician. Attention is focused on the BAEP as it is used in infants and children, starting with a brief review of auditory physiology, then progressing to normative data, clinical utility, physical setup, preparing the patient, comments on technique, and comments on interpretation. This is not an exhaustive review of the topic, and many important elements of clinical utility had to be left out. This review tries to focus on recent references and on practical issues, and it relies on the experience and opinions of the author. Emphasis has been placed on the use of the BAEP by the neurologist, but an attempt has been made to acknowledge the importance of audiology and otolaryngology as well as speech and language science. Particular emphasis has been placed on the use of the BAEP in assessing the premature infant and young infant at risk for neurological and audiological injury. An enormous amount of published data is available in the literature, and much of it had to be left out of this review. However, the reader is encouraged to develop an enthusiasm for the BAEP and to further explore the broad range of its clinical uses.     

Portal-systemic encephalopathy: alterations in somatosensory and brainstem auditory evoked potentials

Median somatosensory and brainstem auditory evoked potentials (SEP and BAEP) were studied in 40 patients with liver cirrhosis consequent to chronic viral hepatitis. The patients were divided into 4 groups: group 1 with liver cirrhosis only, group 2 with hepatic failure (HF), group 3 with grade 1 or 2 hepatic encephalopathy (HE), and group 4 with grade 3 or 4 HE. The control group consisted of 10 age-matched normal subjects. The major changes occurred in the median cortical SEP late components (peaks after N20 and P25). From group 1 to group 4, there were progressive prolongation and sequential disappearance of the late components. Those changes in the cortical SEPs were reversible. The subcortical somatosensory and brainstem auditory conductions (SEP N13-N20 and BAEP I-V interpeak latencies) were slightly prolonged in all groups of patients. The present data indicate that SEP may be useful in detecting subclinical HE and in monitoring the clinical course of HE. The present data further indicate that chronic portal-systemic shunting in liver cirrhosis may result in a minimal impairment of cerebral function and sensory conduction in the CNS.     

Mechanisms of intraoperative brainstem auditory evoked potential changes.

Brainstem auditory evoked potential (BAEP) changes during intraoperative monitoring may reflect damage to or potentially reversible dysfunction of the ear, the eighth nerve, or the brainstem auditory pathways up to the level of the mesencephalon. They may also be caused by other physiologic mechanisms such as anesthesia, hypothermia, and acoustic masking from drilling noise, or they may result from technical factors that prevent proper stimulus delivery or recording of an evoked potential that is actually present. Cochlear ischemia or infarction resulting from compromise of the internal auditory artery and inner ear damage during temporal bone drilling will affect all BAEP components, including wave I. Direct mechanical or thermal trauma to the eighth nerve will delay, attenuate, and possibly eliminate waves III and V, but wave I, which is generated at the cochlear end of the eighth nerve, may be preserved. During scraping of tumor off the eighth nerve, force applied in an ear-toward-brainstem direction can avulse the fragile fibers of the distal eighth nerve at the area cribrosa. Prolonging the I-to-III interpeak interval during retraction of the cerebellum and brainstem reflects stretching of the eighth nerve, and is often reversible. Vasospasm within the eighth nerve can cause similar, potentially reversible BAEP changes. Damage to the brainstem auditory pathways at or below the level of the mesencephalon will delay and attenuate or eliminate wave V. Wave III is affected similarly if the damage is at or caudal to the region of the superior olivary complex. These BAEP changes may reflect direct mechanical or thermal damage to the brainstem, brainstem compression, or ischemia or infarction resulting from vascular compromise. During BAEP monitoring, examination of the pattern of BAEP changes, analysis of their correlation with surgical maneuvers, and investigation for possible contributory technical factors can help to determine the cause of the BAEP changes and provide the appropriate information to the rest of the surgical team.     

Short-latency somatosensory and brainstem auditory evoked potentials in patients with Parkinson's disease

Short-latency somatosensory evoked potentials (SSEPs) and brainstem auditory evoked potentials (BAEPs) were recorded in 44 patients with Parkinson's disease (mean age 67.3 years) and 23 normal subjects (mean age 69.3 years). Patients with Parkinson's disease and normal subjects did not show any significant difference with regard to the interpeak latencies between N13 and N20 central conduction time (CCTs). Likewise, there were no significant differences in CCTs between patients with and without dementia. The interpeak latencies between waves I and V (I-V IPLs) in patients with Parkinson's disease were significantly longer than those of the normal subjects (p less than 0.05). In particular, patients with dementia revealed significant prolongation of I-V IPLs compared to patients without dementia and normal subjects (p less than 0.01, p less than 0.001) although no significant differences were observed between patients without dementia and normal subjects. These results show that auditory brainstem pathways are involved in Parkinson's disease patients with dementia.     

Abnormalities in event-related potential and brainstem auditory evoked response in children with nocturnal enuresis

To evaluate central nervous system functioning involvement in nocturnal enuresis, P300 and N200 event-related brain potentials and brainstem auditory-evoked potentials (BAER) were assessed in a group of 35 enuretic boys aged 7-9 years. The measurements of enuretic group were compared to those of age and sex matched non-enuretics. P300 latency in the enuretic group was significantly longer than in non-enuretic group (420 ms at parietal scalp (Pz), 414 ms at central scalp (Cz) versus 386 ms at Pz, 376 ms at Cz; P < 0.01 and P < 0.01, respectively). Both enuretic and non-enuretic subjects were divided into three subgroups his age. There was no significant difference in terms of both P300 amplitude and N200 latency and N200 amplitude between non-enuretic age subgroups. But, P300 latency over central scalp in 8 years old non-enuretic subgroup was significantly longer than in 9 years old non-enuretic subgroup (P < 0.01). No significant difference was found in latency and amplitude of P300 and N200 latency between enuretic subgroups. However, N200 amplitude at Cz in 8 years old enuretic subgroup was significantly lower than both in 7 years old enuretic subgroup and in 9 years old enuretic subgroup (P < 0.01 and P < 0.01, respectively). There were significant topographical differences in latency and amplitude of P300 and in N200 latency in enuretic age subgroups, only. There was no significant difference in interpeak latencies I-III, I-V and III-V and wave latencies I, III and V of BAERs between enuretic group and non-enuretic subgroup. Longer interpeak and wave latencies of BAERs were found both in 8 years old enuretic subgroup and 8 years old non-enuretic subgroup. CONCLUSION: Longer P300 latency in primer enuretics compare to non-enuretics is an evidence of a maturational delay of central nervous system functioning.     

婴儿痉挛症脑干听觉诱发电位中的γ频带

目的 观察婴儿痉挛症患者脑干听觉诱发电位中γ频带成分。方法 用子波变换分别对正常婴儿、婴儿痉挛症患儿、经过一段时间治疗后的婴儿痉挛症患儿脑干听觉诱发电位信号进行多尺度分析。观察脑干听觉诱发电位信号多尺度成分的分尺度功率随尺度的分布。结果 婴儿痉挛症患儿的脑干听觉诱发电位信号的γ频带的成分缺损严重，其分尺度功率远低于正常婴儿，婴儿痉挛症患儿经过一段时间治疗后脑干听觉诱发电位信号的γ频带成分明显改善，其分尺度功率接近正常婴儿。结论 γ频带对信启在脑干中的接收、传输、加工、综合、反馈等高级功能和人脑的认知活动具有重要作用，γ频带成分缺损导致的信息传导阻滞是引起患儿智能发育迟滞的原因。     

Anosognosia for hemiplegia: somatosensory evoked potential studies.

Somatosensory evoked potential studies in nine patients with anosognosia for left hemiplegia and in one patient with anosognosia for right hemiplegia revealed an absence of response over either hemisphere on stimulation of the median nerve on the hemiplegic side. This apparent lack of cortical processing may underlie the impaired awareness of the hemiplegic side, manifested as anosognosia.     

Preservation of the brainstem auditory evoked potential in non-convulsive status epilepticus.

Brainstem auditory evoked potentials (BAEPs) were recorded from a patient simultaneously experiencing non-convulsive generalized status epilepticus (NGSE). Waves I, III and V were normal but all subsequent waves were absent. This finding indicates that structures within the brainstem adjacent to the generators for the BAEP are likely not affected by NGSE and also illustrates the resilient nature of the BAEP. This is the first report of the recording of an evoked potential during a naturally occurring generalized seizure.     

诱发电位与脑电图联合检测对脑血管病昏迷患者预后的评估

目的研究脑电图（EEG）、脑干听觉诱发电位（BAEP）、体感诱发电位（SEP）联合检测对脑血管病昏迷患者预后的判断。方法对60例脑血管病昏迷患者进行EEG、BAEP、SEP检测,并与预后结果进行分析。结果诱发电位与脑电图联合检测对预后评估的敏感性为96．9％,特异性96．4％,准确率96．7％,与glasgow评分组比较差异有统计学意义P〈0．05。结论EEG、BAEP及SEP联合检测对评价脑血管病昏迷患者脑功能状态,预测预后提供了客观可靠的依据。     

脑干听觉诱发电位在血管性痴呆的应用价值

目的 探讨脑干听觉诱发电位(BAEP)在血管性痴呆患者应用价值.方法 选择200例血管性痴呆患者进行脑干听觉诱发电位(BAEP)检测分析.结果 脑干听觉诱发电位显示研究组III、V波潜伏期(PL)和I～III、III～V、I～V波峰间潜伏期(IPL)及(III～V)/(I～III)比值均高于对照组,差异有统计学意义(P<0.01).结论 脑干听觉诱发电位可客观的反映听觉系统和脑干功能状况,预防疾病进一步发展,对血管性痴呆的临床诊疗及预后均有价值.     

脑干听觉诱发电位对癫(癎)患儿检测的意义

目的探讨脑干听觉诱发电位在癫患儿检测中的意义。方法对2000-01~2008-01我院38例癫患儿BAEP的检测结果进行总结。结果BAEP正常15例(39.5%),异常23例(60.5%),其中21例BAEP改变形式多样,异常指标相混出现。结论癫患者存在脑干功能异常。     

Visual, cortical somatosensory and brainstem auditory evoked potentials following incidental irradiation of the rhombencephalon.

Visual, cortical somatosensory and brainstem auditory evoked potentials were recorded before incidental irradiation of the rhombencephalon and at 11 weeks and eight months after completion of treatment. No patient experienced neurological symptoms during this period. No consistent changes in evoked potentials were found. The failure to demonstrate subclinical radiation-induced demyelination suggests either that the syndrome of early-delayed radiation rhombencephalopathy occurs in an idiosyncratic manner, or that any subclinical lesions are not detectable by serial evoked potential recordings.     

Pattern shift visual evoked potentials in Charcot-Narie-Tooth disease,HMSN type I

Summary Pattern shift visual evoked potentials were investigated in 9 subjects with Charcot-Marie-Tooth disease, who were classified as HMSN I on clinical, genetic and electromyographic criteria. The latency of the second positive peak was increased in 7 eyes of 5 subjects. These results suggest that patients with HMSN I the optic nerves may be affected more frequently than suspected on clinical examinations.

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Zusammenfassung Visuelle, durch Schachbrettmusterumkehr evozierte Potentiale wurden bei 9 Patienten mit einer neuralen Muskelatrophie untersucht. Die Patienten wurden entsprechend genetischer, klinischer und elektromyographischer Befunde als Typ HMSN I klassifiziert. Die Latenzen des zweiten positiven Gipfels der visuell evozierten Potentiale waren in 7 Augen von 5 Patienten eindeutig pathologisch verlängert. Aufgrund dieser Ergebnisse ist es wahrscheinlich, daß der N. opticus in einem höheren Prozentsatz bei Patienten mit einer neuralen Muskelatrophie, Typ HMSN I, betroffen ist als klinisch vermutet werden kann.

     

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 degrees C to 19 degrees 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 degrees 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 degrees C depend on whether that temperature is reached during cooling or during warming.