颅内动脉瘤术中诱发电位监测的初步探讨

目的 初步探讨颅内动脉瘤手术中躯体感觉诱发电位、脑干听觉诱发电位及运动诱发电位的临床应用价值.方法 在16例动脉瘤手术中开展诱发电位监测,观察术中电生理信号改变与术后神经功能状态的关系.结果 11例术中未出现电生理信号异常改变,5例术中出现了异常信号,其中信号未能恢复正常的4例术后均出现新发神经功能障碍.结论 诱发电位监测可实时了解颅内动脉瘤手术中有无脑缺血所致的神经功能障碍,对指导手术及评估预后均有重要意义.

Abstract：

Objective To explore the application of intraoperative neuroelectrophysiological monitoring on somatosensory evoked potentials (SEP), brainstem auditory evoked potentials (BAEP) and motor evoked potentials (MEP) during intracranial aneurysm surgery.Methods SEP, BAEP or MEPs were monitored during operations on 16 patients with intracranial aneurysms.The relationship between the intraoperative changes of electrophysiological signals and the postoperative outcomes of neurological deficits was evaluated.Results 11 patients without abnormal intraoperative electrophysiological signal changes demonstrated no new neurological deficits after surgery.However, in the left 5 patients, abnormal changes of intraoperative electrophysiological signals were detected.Among these 5 patients, 4 with abnormal electrophysiological signals which were not recovered intraoperatively demonstrated new developed functional deficits immediately after surgery.Conclusion During intracranial aneurysm surgery, the monitoring on SEP, MEP and BAEP is beneficial not only to timely detecting neurological functional deficits resulted from intraoperative cerebral ischemia, but also to properly guiding surgical manipulation, and to reliably predicting postoperative outcome as well.     

EEG,evoked potentials and pulsed Doppler in asphyxiated term infants

ObjectiveTo evaluate electroencephalograms (EEG), evoked potentials (EPs) and Doppler findings in the cerebral arteries as predictors of a 1-year outcome in asphyxiated newborn infants.MethodsEEG and EPs (brain stem auditory (BAEP), somatosensory (SEP), visual (VEP) evoked potentials) were assessed in 30 asphyxiated and 30 healthy term infants during the first days (range 1–8). Cerebral blood flow velocities (CBFV) were measured from the cerebral arteries using pulsed Doppler at ∼24 h of age. EEG, EPs, Doppler findings, symptoms of hypoxic ischemic encephalopathy (HIE) and their combination were evaluated in predicting a 1-year outcome.ResultsAn abnormal EEG background predicted poor outcome in the asphyxia group with a sensitivity of 67% and 81% specificity, and an abnormal SEP with 75% and 79%, respectively. Combining increased systolic CBFV (mean + 3SD) with abnormal EEG or SEP improved the specificity, but not the sensitivity. The predictive values of abnormal BAEP and VEP were poor. Normal EEG and SEP predicted good outcome in the asphyxia group with sensitivities from 79% to 81%. The combination of normal EEG, normal SEP and systolic CBFV < 3SD predicted good outcome with a sensitivity of 74% and 100% specificity.ConclusionsCombining abnormal EEG or EPs findings with increased systolic CBFV did not improve prediction of a poor 1-year outcome of asphyxiated infants. Normal EEG and normal SEP combined with systolic CBFV < 3SD at about 24 h can be valuable in the prediction of normal 1-year outcome.SignificanceCombining systolic CBFV at 24 h with EEG and SEP examinations can be of use in the prediction of normal 1-year outcome among asphyxiated infants.     

Longitudinal study of EEG and evoked potentials in neurologically asymptomatic HIV infected subjects

Serial electroencephalograms (EEGs) and multimodality evoked potentials (EPs) were performed along with neurological and neuropsychological evaluation, cerebrospinal fluid assessment and magnetic resonance imaging at 6 month intervals in 73 neurologically asymptomatic HIV infected subjects. The results were compared with 50 age- and sex-matched controls. EEG was abnormal in 2 subjects (3%) initially and was abnormal in 7 (9%) subjects by the last examination. EEG abnormality (diffuse slowing) correlated significantly with slowed reaction time in neuropsychological testing (P<0.05). VEP and BAEP provided low yields of 1.3% and 4% respectively. SEP was abnormal in 7 (9%) of the subjects initially and in 10 (13%) subjects by the last testing, with 80% of the abnormalities seen on the posterior tibial study. In 3 subjects, initial SEP abnormalities predicted later development of myelopathy and peripheral neuropathy.Event-related auditory evoked potentials were performed in 39 subjects. They were abnormal in 5 subjects initially (12%) and in 6 subjects (15%) by the last examination and more commonly in advanced stages of the illness with lower T4 counts. This data shows the evolution and association of electrophysiological abnormalities in early HIV infection and suggests a predictive value for SEP in HIV infected asymptomatic individuals.     

Apport de l''eeg et des potentiels evoques dans le pronostic des comas postanoxiques de l''enfant

Six children with post-anoxic coma were studied and there was evidence of preserved brainstem function together with the presence of electrocerebral activity on EEG. There is no definite prognosis with slow EEG; patients can either die, survive, but with major neurological damage, or recover completely. In that case, evoked potentials have a good prognostic value. Normal BAEP indicate that patients will survive. However, absence of the cortical component of SEP indicates major cerebral damage. Evolution towards a vegetative state can therefore be predicted.     

Continuous and simultaneous monitoring of EEG spectra and brainstem auditory and somatosensory evoked potentials in the intensive care unit and the operating room

Individual monitoring of EEG and evoked potentials is gradually becoming standard in neurosurgery: compressed power spectra during carotid endarterectomy, brainstem auditory evoked potentials (BAEP) during posterior fossa surgery, and somatosensory evoked potentials (SEP) mainly during spinal cord surgery. In this paper, a new technique is described in which EEG, BAEP, and SEP are recorded and evaluated simultaneously and continuously. This allows a better survey of different neuronal structures and systems in the brain and brainstem. First results from intraoperative and intensive care patient monitoring are reported.     

Multimodal evoked potentials in human immunodeficiency virus infection

We have studied 95 HIV seropositive patients (77 males and 18 females; mean age: 31 years): 67 had no neurological symptoms or signs, 28 had various neurological symptoms and signs. This study included a full multimodal evoked potentials (MEP) assessment: visual evoked potentials by flash and reversal checkerboard; brainstem auditory evoked potentials; somatosensory evoked potentials obtained by stimulation of the median nerve. Patient evaluation further included: electroencephalography, electromyography with measurement of conduction velocities and neuroimaging (brain CT scan and/or MRI). We found abnormal MEP for all modalities. The prevalence of abnormal results was high in neurological symptomatic patients; in non neurological ones, the changes tended to be more frequent with the progression of the HIV infection. Whatever the stage of the disease, the various modes were equally affected. MEP were abnormal in 54.7 p. 100 of the cases: in 41.8 p. 100 (28/67) of patient without neurological signs (in 4/12 of fully asymptomatic subjects, 11/34 ARC patients and 13/21 AIDS patients) vs 85.7 p. 100 of neurological symptomatic patients. In neurological asymptomatic patients, a similar proportion of abnormal MEP was found in asymptomatic and ARC patients, while the evolution into AIDS was associated with a higher prevalence of abnormal MEP. In the latter group, MEP changes were nearly as frequent as in neurological symptomatic patients. Comparison between MEP and other electrophysiological procedures (EEG, EMG) and with neuroimaging techniques (CT Scan, MRI) showed the high sensitivity of the MEP technique at all stages of the disease. EMG was a sensitive method and complementary to MEP. The EEG and neuroimaging techniques showed abnormalities principally at the neurological symptomatic stage. Previous studies could not be properly compared.(ABSTRACT TRUNCATED AT 250 WORDS)     

Monitoring of sensory evoked potentials during surgery of skull base tumours

Despite advances in instrumentation and the use of microsurgical techniques, neurosurgical procedures involving extensive areas of skull base or other critical areas of brain still carry significant risk for neurological injury. The use of intraoperative recording of sensory evoked potentials (SEP) has been advocated to monitor neurologic function during these major neurosurgical procedures to reduce the risk of injury to neural structures. This report summarizes our experience with intraoperative monitoring of SEP in over 200 patients, and details our findings in a group of 12 patients with skull base and posterior fossa tumours. Somatosensory evoked potentials (SSEP) were monitored in all patients, and brain stem auditory evoked potentials (BAEP) in five. While minor changes in BAEP and SSEP parameters were noted in most patients, significant changes occurred in five. Irreversible loss of BAEP in one patient was associated with complete hearing loss postoperatively. Marked, persistent alteration of both BAEP and SSEP was associated with postoperative brainstem dysfunction. No patient with stable BAEP and SSEP at the end of the procedure suffered additional neurological deficit. We conclude that intraoperative SEP monitoring may be valuable in minimizing neural injury during major neurosurgical procedures.     

脑干听觉及体感诱发电位对重型颅脑损伤病人预后的判断

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。方法应用诱发电位仪对85例重型颅脑损伤患者早期行BAEP及SEP检查,并进行动态监测。结果重复检查BAEP及SEP均正常者,预后良好;BAEP及SEP均异常者,预后极差,与其他几组比较均有显著性差异(P<0.05)。结论BAEP与SEP联合应用并重复检查,可以比较准确的评估重型颅脑损伤患者的预后。     

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.     

Brain-stem auditory evoked potentials in children with perinatal encephalopathies.

OBJECTIVE: We sought to describe if neurological damage, in terms of brain lesions, syndrome and syndrome severity led to abnormalities in the brain-stem auditory evoked potentials (BAEPs) in order to provide a profile of children that could be used as an indicator of subsequent neurological sequelae. We analyzed the BAEPs from a group of children having prior evidence of neurological damage and determined the presence of neurological sequelae when the subjects were 3 years old. METHODS: Brain-stem auditory evoked potentials (BAEPs) were carried out in a group of 154 children with perinatal neurological damage. The children were classified with neurofunctional (clinical and EEG alterations) or organic and neurofunctional brain disease (clinical, EEG and image alteration) and were all followed from the first month of life and serially for 3 years. We used principal component analysis (PCA), clustered analysis and linear correlation to determine association between BAEPs, risk factors and future sequelae. RESULTS: Latencies of BAEPs decreased significantly with age, and the time of conduction was modified by the presence of neurological damage. All statistical analyses suggested positive and significant associations between risk factors (trophism and condition at birth), and the latencies of waves I, III and V as well as with IPL III-V (interpeak latency) and I-V. PCA showed that IPL I-III was also positively associated with condition at birth, severity of the neurological syndrome and encephalopathy. In addition, we found that the presence and type of sequela reflected changes in the latencies of the waves, as well as IPLs, primarily those of IPL I-III. CONCLUSIONS: Our results suggest that statistical methods are often needed to analyze neurological damage. The relation between BAEPs, risk factors and neurological sequelae allowed us to obtain a profile of children, which can be then used as an aid in the prognosis of children having a risk of developing neurological sequelae.     

卡马西平对诱发电位的影响及意义

目的研究长期口服卡马西平治疗癫对诱发电位的影响,并讨论其意义。方法选择尚未治疗的癫病人31例作为试验组;以性别、年龄与癫组相匹配的健康正常人26例作为对照组。两组先分别做脑干听觉诱发电位(BAEP)、事件相关电位P300、视觉诱发电位(VEP)和体感诱发电位(SEP),之后癫组开始卡马西平治疗,服药一年后再作上述各项检查。结果癫组病人治疗前各项电生理学指标与正常对照组相比无显著性差异;癫组卡马西平治疗后各项电生理指标与治疗前相比BAEP各波、P300以及VEP的P100波潜伏期均显著延长;SEP的潜伏期无显著变化。结论神经电生理学检查可以早期发现长期服用卡马西平导致的亚临床毒性。     

Evaluation of electrophysiological neuromonitoring in the diagnosis of brain death: Part III. Compressed spectral arrays

Electrophysiological neuromonitoring of compressed spectral array (CSA) EEG, brainstem auditory evoked potentials (BAEP) and short-latency somatosensory evoked potentials (SEP) can provide precise and immediate information concerning functional integrity of severe brain damage. We applied this neuromonitoring system in 185 cases of severe brain damage in order to evaluate its reliability in the diagnosis of brain death. This report considers the relationships between CSA and neurological, conventional EEG (CEEG), BAEP and SEP findings, and the significance of CSA in the assessment of brain death. CSA monitoring of 59 patients (37 brain-dead in group A and 22 non brain-dead in group B) was performed and analysed. Brain damage was caused by cerebrovascular insult in 31 cases, head injury in 25, meningitis in 2, dan anoxia in 1. Mean patient age was 49 (ages 5-84). There were no significant differences in causes and age distribution between the two groups. CSA monitoring, using 5 or 7 microV/mm, of two channels (Cz-A1 and Cz-A2) of EEG activity was performed. Power spectral analysis (0-16 Hz) was carried out at 10 to 120 second epochs. Automatic BAEP (54 patients) and/or SEP (33 patients) monitoring was performed simultaneously 10 to 30 minutes. CSA was classified into three patterns: 1) "Electrocerebral silence; ECS" revealed bilateral absence of the CSA power spectra for periods longer than 40 seconds. 2) "Biological activity; BA" showed continuous peaks of activity. 3) "Equivocal; EQ" pattern showed intermittent peaks of activity, and unilateral loss of power spectra or bilateral loss within 30 seconds. CSA findings indicated the loss of CSA "BA" pattern (LCBP) in 36 group A patients (17 "ECS" and 19 "EQ"). All but two revealing LCBP had satisfied the neurological criteria of brain death (deep coma, absent brainstem reflexes and apnea) during CSA monitoring. "BA" was always present in 22 group B and one group A patients had not fulfilled neurological criteria of brain death. The CEEG results of all group A patients demonstrating "ECS" of CSA were of the classification Hockaday grade Va or Vb. Four patients classified as grade IV b demonstrated "EQ" An examination of CSA and neurological brainstem function of 28 group A patients revealed LCBP preceded the loss of brainstem reflexes and apnea in 15 patients or was coincided with them in 13.(ABSTRACT TRUNCATED AT 400 WORDS)     

CT, somatosensory and brainstem auditory evoked potentials in the early prediction of functional outcome in putaminal hemorrhage

The CT and median somatosensory and brainstem auditory evoked potentials (SEP and BAEP) were studied in 80 patients with spontaneous putaminal hemorrhage for their values in the early prediction of functional outcome. The CT scan was performed within 2 days and EPs within a week after the onset of symptoms. The activities of daily living was assessed at 6 months. Patients with good functional recovery had the following findings: 1) the hemorrhage had not involved the thalamus or the posterior limb of the internal capsule; 2) the SEPs were normal or had prolonged central conduction time; and 3) the BAEP was normal. When the cortical SEPs were absent, the majority of patients were moderately or severely disabled. Attenuation or absence of BAEP wave V always forecast a grave prognosis. It is concluded that the combined use of CT, SEP and BAEP is an objective and reliable method for the early prediction of functional outcome in patients with putaminal hemorrhage.     

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.     

Effects of thiopental on sensory evoked potentials in the cat

Noninvasive electrophysiological evaluation with sensory evoked potentials would be of clear diagnostic and prognostic value in evaluating comatose patients with stroke or severe head injury. In order to protect the brain from such kinds of insults, barbiturate coma therapy has been employed and its effectiveness has been already established. However, in the barbiturate coma therapy, it is occasionally difficult to distinguish the pharmacological effect of barbiturate from the preexisting brain dysfunction caused by the underlying process of the disease. In adult cats, authors studied changes of sensory evoked potentials following cumulative intravenous administration of thiopental which is used clinically for barbiturate coma therapy. P1 and N1 of cortical SEP showed tendency of gradual decrease in amplitude. However, no significant changes occurred in latency by stepwise increment of thiopental dose. Changes in amplitude of P1 and N1 of cortical SEP preceded to the flattening on electroencephalogram. Around at the level of the concentration where EEG changes began, I-II interpeak latency of BAEP and latency of wave I of short latency SEP started to increase. BAEP and early components of SEP (I.II.III.IV) persisted even in by far the higher level of serum concentration of thiopental than that of clinical use. Furthermore, most of these parameters showed no statistically significant change neither in amplitude nor in latency. These experimental results suggest that sensory evoked potentials will provide us with useful information in the assessment of the brainstem function in patients under thiopental induced deep coma.     

Evoked potentials in HIV infection]

The study of the literature data on the multimodal evoked potentials in HIV infected patients shows many abnormalities as well in asymptomatic subjects without AIDS as in AIDS subjects with or without neurological signs. Visual evoked potentials (VEPs) reveal prolonged P100 wave latency in 22% of HIV asymptomatic subjects and in 26% of HIV symptomatic subjects; brainstem auditory evoked potentials (BAEPs) reveal an increase of the interpeak latency I-V in 16% of asymptomatic subjects and in 32% of symptomatic subjects; somatosensory evoked potentials (SEPs) by median nerve stimulation reveal prolonged central conduction time in 6% of asymptomatic subjects and in 11% of symptomatic subjects; somatosensory evoked potentials (SEPs) by tibial nerve stimulation reveal prolonged central conduction time in 4% of asymptomatic subjects and in 45% of symptomatic subjects; motor evoked potentials (MEPs) by magnetic stimulation reveal prolonged central motor conduction time in 46% of asymptomatic subjects.     

Brain-stem auditory evoked potentials in multiple sclerosis: the relation to VEP,SEP and CSF immunoglobulins

Summary One hundred patients with multiple sclerosis (MS) were analysed retrospectively with respect to investigations of brain-stem auditory evoked potentials (BAEP), pattern reversal visual evoked potentials (VEP), somatosensory evoked potentials (SEP), and cerebrospinal fluid immunoglobulins (CSF-IG). BAEP were abnormal in 42% of those with normal VEP and SEP examinations, and in 38% of patients with normal CSF-IG. The chance of obtaining at least one abnormal EP was lower in patients with normal CSF-IG than in patients with abnormal CSF. When a dispersion ratio was included in the criteria for BAEP abnormality, the sensitivity increased compared with conventional BAEP criteria. We recommend that BAEP should still be included in the EP test battery for patients with suspected MS.     

Evoked potentials and CSF-immunoglobulins in MS: relationship to disease duration, disability, and functional status

In 100 MS patients, BAEP and tibial SEP abnormality rates increased significantly with disease duration and clinical disability. VEP correlated non-linearly with disease duration, and median nerve SEP correlated with disability. In multifactorial analysis, however, BAEP correlated significantly only with clinical brainstem and cerebellar signs. These results suggest that evoked potentials correlate more strongly with neurological status of the functional subsystems than either overall disability or disease duration. These findings indirectly suggest that evoked potentials may be useful monitors during large therapeutical trials in MS patients.     

Transcranial magnetic stimulation in Beh?et's disease: a cross-sectional and longitudinal study with 44 patients comparing clinical, neuroradiological, somatosensory and brain-stem auditory evoked potential findings.

OBJECTIVES: To compare neurological involvement in Beh?et's disease as documented by transcranial magnetic stimulation (TMS) with clinical, neuroradiological, somatosensory (SEP) and auditory evoked potential (BAEP) findings. METHODS: Forty-four patients were studied over an 8 year period. Nine patients had follow-up studies done. TMS central motor conduction (CMC) studies to upper and lower limb muscles, brain magnetic resonance imaging (MRI), SEP, and BAEP testing were conducted. RESULTS: Thirty-nine patients had CMC slowing, decreased amplitude or absent motor evoked potentials (MEP); 5 of these patients were neurologically normal. Concordance of TMS results, clinical deficits, and MRI findings occurred in 36 of the 39 patients. SEP and BAEP testing proved non-complementary to MEP. Generally, follow-up studies revealed faster CMC and higher MEP amplitude. However, in two patients the CMC time to one target muscle became prolonged with diminished MEP amplitude over a period of 1.5-3 years. CONCLUSIONS: TMS can be useful in detecting and quantifying motor tract dysfunction in Beh?et's disease and provides functional information complementary to imaging studies. TMS is more sensitive than either SEP or BAEP. Our longitudinal studies suggest that TMS studies may be valuable in monitoring disease activity or therapeutic response.     

Neurophysiologic assessment of mucopolysaccharidosis III.

OBJECTIVE: To describe finding of various neurophysiologic tests in patients with mucopolysaccharidosis III (MPS III) early in the disease course. METHODS: Patients were evaluated with flash visual evoked potentials (VEP), brainstem auditory evoked potentials (BAEP), electroencephalography (EEG), and nerve conduction studies (NCS) before they underwent hematopoietic stem cell transplantation (HSCT). RESULTS: Thirteen children underwent at least one neurophysiologic test before HSCT. The mean age at testing was 2.7 years. Ten of 11 (91%) patients had a normal flash VEP, and all 9 who had BAEP had normal central conduction. EEG was normal in 7/13 (54%), with the others showing diffuse slowing. NCS was normal in 10/11 (91%) patients. CONCLUSIONS: Despite extensive central nervous system involvement in MPS III, flash VEP and BAEP are almost always normal. EEG is often abnormal early in the disease. SIGNIFICANCE: This is the first report of neurophysiologic tests in a large series of MPS III patients.