Multimodal evoked potentials in the early period after cranio-cerebral trauma]

In 83 patients aged 17-68 years somatosensory evoked potentials by median nerve stimulation, and visual and auditory evoked potentials were studied 5-28 days after craniocerebral trauma. Brain concussion was diagnoses in 43 cases on the basis of neurological examination, CT and duration of unconsciousness. In the remaining 40 cases brain contusion was diagnosed. In SSEP the latency was calculated of waves N9, N13, P16, N20, P22, N35 and P40: in the visual evoked potentials the latency of the P100 component, and in auditory evoked potential the latency of waves I, III and V, and interpeak latency I-III, III-V and I-V SSEP changes were found in 39% of cases of brain concussion and 52.9% of brain contusion cases. The abnormalities in both groups involved mainly the component of latency and deviation P100 of visual evoked potential P40 and N35. Prolongation of the latency of P100 of the visual evoked potential was recorded in 20% of patients with brain concussion and 16.7% with brain contusion. Auditory evoked potentials were abnormal in 10.3% of brain concussion and 26.5% of brain contusion cases. In 64 cases all three types of evoked potentials were studied and pathological changes in at least one of these types were found in 56.4% of brain concussion and 72% of brain contusion cases. The results show that as least in a part of cases diagnosed as brain concussion according to generally accepted criteria, central nervous system injury is present.     

Results of prospective 24-hour EEG studies of patients after cranio-cerebral injuries]

In 26 patients 24-hour cassette EEG recording and routine EEG records were taken between 6 and 35 days and again between 6 and 12 months after craniocerebral trauma. Neurological examination and CT of the head demonstrated cerebral concussion in 11 cases and brain contusion in 15 cases. Early after trauma routine EEG was abnormal in 5 cases (19.2%) exclusively in those with brain contusion, and 24-hour EEG recording was abnormal in 16 cases (61.5%), including 7 with cerebral concussion and 9 with brain contusion. In the second half year after trauma 24-hour EEG was normal in 5 cases (19.2%) which had previously abnormal records, and abnormal EEG changes appeared in 6 cases (23.1%) with previously normal findings. Seizure activity was found in the first weeks after trauma in 9 (34.6%) 24-hour recordings. In the second half year after trauma seizure activity was no longer present in 2 cases, but appeared in 6 other cases. Thus 24-hour recording between 6 and 12 months after trauma demonstrated seizure activity in 50% of all patients. In 2 of them epileptic fits developed. The study shows that repeated 24-hour EEG recording after craniocerebral trauma may be important in early detection of patients who are at risk of epilepsy development.     

Early and late outcome in head injury patients with radiological evidence of brain damage

This study examined the early and late outcome in head injury patients with focal or multifocal (unilateral or bilateral) brain contusions revealed by computerized tomography (CT) scanning. The outcome was also evaluated in patients hospitalized due to brain concussion. Three months after the injury (the early outcome) 43% of the 86 cases with multifocal contusions on the CT scan were dead. As evaluated by the Glasgow Outcome Scale, all the 57 patients with a focal brain contusion, as well as the 117 cases with brain concussion, made a good recovery or were moderately disabled. The late outcome (1 to 5 years after injury) was evaluated in 78 cases with brain contusion and in 85 cases with brain concussion, and revealed that complaints and impaired adaptive functioning were frequent in both the contusion and concussion group. The occurrence of headache, dizziness and sleep problems did not significantly differ among the various head injury groups. However, focal or multifocal brain contusions on the CT scan increased the frequency of impaired memory, impaired concentration, speech problems, weakness in arms or legs and seizures with loss of consciousness. Cognitive deficits and speech problems were particularly common in patients with a focal contusion in the temporal lobe. The late adaptive and social functioning were most markedly impaired in cases with multifocal bilateral contusions.     

Evoked potentials in head injury and states of increased intracranial pressure

Recent clinical studies have addressed the utility of sensory evoked potentials (auditory, somatosensory, and visual) in head injury. The clinical significance of evoked potentials in head trauma, states of increased intracranial pressure, and post-traumatic syndrome is discussed. Emphasis is placed on up-to-date studies discussing evoked potential correlation with clinical findings, lesion localization, intracranial pressure, brain herniation, and prognosis.     

Fos蛋白和Jun蛋白在犬颅脑枪弹伤局部脑组织的表达

目的　研究犬颅脑枪弹伤后脑神经元早期快反应基因c fos和c jun表达产物Fos蛋白和Jun蛋白的变化规律。方法　 2 0只杂种犬 ,随机分为正常对照组、损伤组。以德国小口径步枪子弹致犬颅脑贯通伤 (PCI)模型为对象 ,采用免疫组化法检测脑组织伤后 30min、2h、6h弹道挫伤区、震荡区及脑干神经元中Fos和Jun蛋白的表达。结果　对照组脑皮质神经元中Fos和Jun蛋白弱表达 ,弹道挫伤区、震荡区及脑干神经元中Fos和Jun蛋白表达于伤后 30min开始增加 ,2h达到高峰 ,6h逐渐下降。且Fos和Jun蛋白表达在弹道震荡区较挫伤区更为明显 (P <0 .0 5 )。结论　Fos蛋白和Jun蛋白在弹道挫伤区、震荡区及脑干神经元均有表达 ,c jun在脑组织内表达的分布范围及变化趋势与c fos基本一致 ,其表达是对损伤刺激的早期反应 ,可能是由Leao播散性抑制引起 ,并与细胞内外信号转导和细胞凋亡有关。     

Neurophysiological evaluation using multimodal sensory evoked potentials in patients in coma: general aspects

Noninvasive sensory evoked potentials (SEP) performed at bedside in the Intensive Care Unit for patients in coma can be helpful in establishing both a diagnosis and a prognosis. Based on a more than 6-year experience on this subject, the authors discuss general aspects concerning these EP, their probable known generators, and propose a classification depicting different aspects observed for flash visual EP (F-VEP), brainstem auditory EP (BAEP), and median nerve somato-sensory EP (SSEP). Isolated, SSEP shows the best diagnostic and prognostic performance. Nevertheless, the authors consider that multimodality SEP are even better than any isolated EP study; cross-correlating information generated through a horizontal (F-VEP), a vertical (SSEP), and a pathway focusing brainstem in greater detail (BAEP) allows the neurophysiological establishment of the level of lesion in the CNS from a better perspective; besides, SEP can help setting the diagnosis of brain (encephalic) death, and the diagnosis of particular problems concerning each pathway. Notwithstanding, most important is prognosis definition, and the findings are summarized. Abnormal BAEP implies bad prognosis, as would be expected considering the severity of a brainstem lesion; on the other hand, a normal BAEP per se does not allow a precise definition, resting on other EP the role prognosis characterization. SSEP if bilaterally normal or only mildly abnormal imply good prognosis; bilateral absence of SSEP thalamo-cortical components has always carried a bad prognosis, since younger patients may at best evolve into a persistent vegetative state; SSEP intermediary results are more often accompanied by variable evolution. FVEP results parallel those of SSEP.     

The importance of brain stem evoked potentials in the diagnosis of neurosurgical patients]

The technique of Brainstem Electric Response Audiometry (BERA) is a non-invasive electrophysiologic method used in comatose patients for localization of areas of neuronal and synaptic dysfunction not evident in clinical evaluation. This test has a diagnostic and prognostic value in detection of abnormalities and evaluation of comatose head-injured patients at a reversible clinical stage. In contrast to most clinical signs, brainstem auditory evoked potentials are independent of levels of consciousness, analgesics, sedatives. This test is aetiologically non-specific and must be carefully integrated into the clinical situation. Generators of brainstem auditory evoked potentials are located in the auditory nerve (waves I and II) and brainstem (waves III-V). Patients in acute posttraumatic coma are assessed by means of Glasgow Coma Score (GCS), which is reliable in forecasting a favourable outcome. Patients with a score 8 points have an unfavourable outcome in 16%. Brainstem auditory evoked potentials are reliable predictors of unfavourable outcome. Subsequent brainstem auditory evoked potential testing provides relevant prognostic information, since improvement of graded brainstem auditory evoked potentials indicates a favourable outcome. Progressive deterioration of brainstem auditory evoked potentials indicates irreversible damage and is associated with unfavourable outcome, whereas singular abnormal evoked potentials may result from reversible neuronal dysfunction. The absence of waves III-V associated with the end EEG activity is the proof of brain death. Serial BERA monitoring has been used to evaluate progressive clinical syndromes, such as "uncal herniation" and evolving brain death. The use of serial BERA recordings appeared to improve the outcome predictions in comparison with single BERA tests. A combination of brainstem auditory evoked potentials, somatosensory and visual evoked potentials (multimodality evoked potentials-MEP) provides more information for management of a patient than a single evoked potential modality. The main goal to use BERA is early detection of secondary deterioration in comatose patients suffering from intracranial lesions. The results of brainstem auditory evoked potentials and clinical examination of patients obtained within the acute phase after head injury may indicate increased intracranial pressure (ICP) and incipient transtentorial herniation but do not always predict outcome (GOS). The outcome can be better evaluated later, 3-6 days after head injury. In summary, BERA is a non-invasive, safe and objective method of evaluating patients after severe head injury and adds valuable information for assessment of their outcome.     

24-hour monitoring of bioelectric activity of the brain in patients after cranial injuries]

In patients after craniocerebral trauma 24-hour EEG and routine EEG records were obtained. 44 cases were studied between 6 and 38 days after trauma and 45 cases were examined between 6 and 12 months after trauma. The diagnosis of brain commotion in early phase based on neurological examination and computed tomography was made in 22 cases, while in 22 cases late posttraumatic phase was diagnosed. Brain contusion in early and late phase was diagnosed in 22 and 23 cases, respectively. Early after craniocerebral trauma the study demonstrated changes in routine EEG in 8 cases (18.1%), while 24-hour EEG demonstrated them in 26 cases (59.0%), that is three times more as frequently. Changes in 24-hour EEG were found nearly twice as frequently than in routine EEG 6-12 months after trauma (51.0% and 28.9% respectively). In patients with brain commotion in the first week after trauma only 24-hours EEG revealed changes. Late after trauma 24-hour EEG could demonstrate seizure activity more frequently than routine EEG.     

Electrophysiological studies in spinocerebellar ataxia type 6: a statistical approach

In spinocerebellar ataxia type 6 (SCA6), the cerebellum is predominantly affected, but several electrophysiological studies have revealed subclinical disorders other than cerebellar lesions. We conducted statistical analyses by comparing SCA6 patients and age-matched normal controls to asses whether electrophysiological abnormalities are directly associated with SCA6 because late onset of SCA6 may involve senile changes. We performed brain stem auditory evoked potentials (BAEP), visual evoked potentials, somatosensory evoked potentials and nerve conduction studies in 10 SCA6 patients. The BAEP latencies of wave I was prolonged and compound muscle action potentials of peroneal nerve and sensory nerve action potentials of sural nerve reduced in SCA6 patients. Our results suggest an existence of peripheral impairment in the auditory pathway and axonal neuropathy in SCA6.     

Experimental study of brain stem infarction in dogs--effect on BAEP, SSEP, blink reflex and EEG of perforator occlusion

Assessment of the lesion in the brain stem by evoked potentials has not been well established. We have already developed a model of brain stem ischemia by occluding the perforators of the posterior cerebral arteries of the dog. The ischemic lesions locates mainly in the ventral side of the midbrain. Using this model, we assessed brain stem function by brain stem auditory evoked potential (BAEP), surface- and depth-recorded (in medial lemniscus) short latency somatosensory evoked potential (SSEP), blink reflex (BR) and electroencephalography (EEG), and investigated the correlation between the electrophysiological abnormalities and the lesion in the brain stem. The studies were performed for 6 hours after perforator occlusion. Furthermore, depth-recorded SSEP and regional cerebral blood flow (rCBF) were measured under induced hypotension by withdrawal of arterial blood. BAEP did not change in 13 of 16 animals. Surface-recorded SSEP remained unchanged in all 6 animals. The results are probably due to the fact that the lesion does not involve the auditory and somatosensory pathways and the accompanying events such as edema does not affect the both pathways. Depth-recorded SSEP remained unchanged after occlusion and did not disappear even when rCBF fell below 10 ml/100 g/min. It may be suggested that the threshold for electrical failure in the brain stem is much lower than that in the cortex. In BR, R1 did not change but ipsilateral R2 became nearly invisible immediately after perforator occlusion in all animals. The fact that the ischemic lesion did not involve the pons and disturbed reticular formation in the midbrain may probably account for the remaining of R1 and the disappearance of ipsilateral R2.(ABSTRACT TRUNCATED AT 250 WORDS)     

气功所致精神障碍患者脑诱发电位系列实验研究

目的 研究气功所致精神障碍患者与正常人在诱发了诱发电位的检测中的不同特点。方法 应用美国仪器和四种方法，对１２例气功偏差所致精神障碍患者和５２例正常人的诱导电位作了检测。结果 与正常人比较，患者组ＡＥＰ的Ｐ１、Ｐ２、Ｎ２、Ｐ３；ＶＥＰ的Ｎ１、Ｎ２、Ｐ３和ＳＥＰ的Ｐ２潜伏期均明显延迟ＡＥＰ、ＶＥＰ和ＳＥＰ的若干波幅同时明显改变。另在ＣＮＶ中机见Ｐ１ＮＶ和Ａ－Ｃ潜伏期延迟，波畅Ｂ增大，Ａ－Ｓ２＾－和Ｓ     

Assessment of regional blood flow in patients after mild head trauma]

Single photon emission computerized tomography (SPECT) using radioisotope markers was applied for analysis of regional blood flow in the brain. The method makes possible demonstration of the presence and extent of damage to the nervous tissue caused by trauma. The degree of blood flow impairment is of prognostic significance in cases of cerebral concussion. In the present study the regional brain blood flow was assessed shortly after trauma and one year in cases of mild cerebral concussion. In the studied group immediately after trauma blood flow impairment was found mostly in the left temporal area and in frontal areas. Changes of rCBI were present also late after trauma. In 7 out of 16 cases SPECT image failed to change one year after trauma. In 8 cases the rCB improved up to normalization. In 1 case the changes progressed, in another case hyperperfusion focus changed to hypoperfusion. In 2 cases the pattern was normal early and lata after trauma. In the studied group in cases with changed rCBF no changes were found in CT and MRI examinations. This evidence a greater sensitivity and usefulness of SPECT in the assessment of early and late consequences of head trauma.     

The diagnostic reliability of magnetically evoked motor potentials in multiple sclerosis.

In a prospective study, we evaluated the technique of magnetically evoked motor potentials (MEP) in the diagnosis of multiple sclerosis (MS). We consecutively included 68 patients with symptoms or signs compatible with a demyelinative CNS affection. We subjected all patients to CSF analysis, MRI studies of the brain and brainstem, visual evoked potentials (VEP), brainstem auditory evoked potentials (BAEP), and somatosensory evoked potentials (SSEP). We then used the results to categorize the patients according to the Poser criteria of multiple sclerosis. Blinded from the results of the above investigations, one of the authors made MEP recordings from three muscles in the upper limbs and two in the lower limbs in all 68 patients. Forty patients received an MS diagnosis, and in these, MRI was positive in 88%, MEP in 83%, VEP in 67%, SSEP in 63%, and BAEP in 42%. As to the diagnosis of MS, the reliability of a prolonged central motor conduction time (CMCT) was 0.83 (0.73 to 0.93), while the reliability of a normal CMCT was 0.75 (0.61 to 0.98). The information gained by MRI was best supplemented by VEP. Of the neurophysiologic tests, the MEP was in closest agreement with the MRI with a concordance of 85%.     

Correlation between morphological abnormalities of Chiari malformation and evoked potentials]

We studied correlation between morphological abnormalities of Chiari malformation and evoked potentials (short-latency somatosensory evoked potential [SSEP] and auditory brainstem response [ABR]). On SSEP the inter-peak latency prolongation of P3-N1 was revealed in 6 out of 8 cases with Chiari malformations. The feature of positive wave between P3 and N1 was divided into 2 groups. The tendency of the positivity between P3 and N1 was more marked in cases of prolonged P3-N1 latency and correlated with the medullary kink. On ABR the prolongation of III-V inter-peak latency was revealed in one side in 3 patients Chiari malformations with malformed pons and tegmentum.     

Electroencephalogram and evoked potential parameters examined in Chinese mild head injury patients for forensic medicine

Objective To evaluate the usefulness of quantitative electroencephalogram （QEEG）, flash visual evoked potential （F-VEP） and auditory brainstem responses （ABR） as indicators of general neurological status. Methods Comparison was conducted on healthy controls （N=30） and patients with brain concussion （N=60） within 24 h after traumatic brain injury. Follow-up study of patient group was completed with the same standard paradigm 3 months later. All participants were recorded in multi-modality related potential testing in both early and late concussion at the same clinical setting. Glasgow coma scale, CT scanning, and physical examinations of neuro-psychological function, optic and auditory nervous system were performed before electroencephalogram （EEG） and evoked potential （EEG-EP） testing. Any participants showed abnormal changes of clinical examinations were excluded from the study. Average power of frequency spectrum and power ratios were selected for QEEG testing, and latency and amplitude of F-VEP and ABR were recorded. Results Between patients and normal controls, the results indicated： （1） Highly significance （P 〈 0.01） in average power of α1 and power ratios of θ/α1, 0/α2, α1/α2 of EEG recording; （2） N70-P 100 amplitude of F-VEP in significant difference at early brain concussion; and （3） apparent prolongation of Ⅰ～Ⅲ inter-peak latency of ABR appeared in some individuals at early stage after concussion. The follow-up study showed that some patients with concussion were also afflicted with characteristic changes of EEG components for both increments of α1 average power and θ/α2 power ratio after 3 months recording. Conclusion EEG testing has been shown to be more effective and sensitive than evoked potential tests alone on detecting functional state of patients with mild traumatic brain injury （MTBI）. Increments of α1 average power and θ/α2 power ratio are the sensitive EEG parameters to determining early concussion and evaluating outcome of postconcussion symptoms （PCS）. Follow-up study associated with persistent PCS may be consistent with the postulate of substantial biological, rather than psychological origin. The study suggests that combination of EEG and EP parameters can contribute to the evaluation of brain function as a whole for clinical and forensic applications.     

Dissociation of somatosensory and motor evoked potentials in non-comatose patients after head injury.

OBJECTIVES: This study was performed to evaluate the clinical value of combined use of somatosensory evoked potentials (SEPs) and motor evoked potentials (MEPs) in patients with different brain lesions after head trauma. METHODS: A total of 64 patients with minor and moderate head injury were investigated by means of SEPs recorded over the parietal and frontal areas and MEPs following single-pulse transcranial magnetic stimulation (sTMS) and slow-rate repetitive transcranial magnetic stimulation (rTMS). RESULTS: In almost 50% of the patients, a dissociated impairment of somatosensory and motor evoked potentials was found. This dissociation was related to different distribution of SEP and MEP abnormalities in head injury subgroups. The higher threshold to sTMS and increased variability of the MEP amplitude during slow-rate rTMS were the most prominent features in patients with focal brain contusions, suggesting impairment of the cortical excitability. SEP abnormalities, as well as central conduction impairments, were more noticeable in patients with diffuse brain injury. CONCLUSIONS: A combined analysis of SEPs and MEPs may improve the assessment of cortical dysfunctions and central conduction abnormalities in non-comatose patients with head injury. A slow-rate rTMS may be considered as a complementary technique to the evaluation of the threshold in assessment of the excitability of the motor cortex in minor and moderate head injury.     

Late auditory evoked potentials can occur without brain stem potentials

The sequence of early, middle and late auditory evoked potentials is well known. However, it is unknown whether the late (60-250 msec) potentials can occur independently of the early, brain stem potentials. Therefore, in 6 subjects with markedly abnormal or absent brain stem potentials, we recorded two of the late potentials: the vertex potential and the T-complex. The latter is a putative product of auditory cortex. Both of these potentials were clearly evident in all patients in spite of the absence of or marked abnormalities in brain stem potentials.     

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.     

A prospective study of “undiagnosed” isolated myelopathy: II. Value of magnetic resonance imaging,evoked potentials and CSF analysis

We aimed to determine the sensitivity of available “diagnostic” tests in detecting subclinical abnormalities characteristic of multiple sclerosis (MS) in patients with unexplained isolated myelopathy, and any relationship between test results and level of disability. The trial investigations were carried out in 69 prospectively selected patients with acute or chronic noncompressive myelopathies. Magnetic resonance scans were the most sensitive individual tests, revealing asymptomatic brain lesions in 51 patients (74%, C.I. 64–84). An abnormal IgG/albumin ratio (IgG/A) was present in 29 (42%, C.I. 30–54), oligoclonal bands (OCB) in 27 (39%, C.I. 17–39) and abnormal evoked potentials (EP) (visual and/or auditory brain stem) in 19 cases (28%, C.I. 17–39). OCB and abnormal EP were found significantly less often than in control patients with clinically definite MS (CDMS) and significantly more often than in patients with myelopathy due to other conditions. The number of anatomical brain areas with lesions on magnetic resonance imaging (MRI) was significantly associated with CSF abnormalities; abnormal EP were correlated with abnormal MRI and elevated CSF immunoglobulins. Clinical classifications, age, symptom duration, disability levels and genetic factors did not appear to influence the prevalence of abnormal MRI or CSF. For the exclusion of compressive and structural diseases of the spinal cord, myelography has been superceded by cervical and thoracic MRI. In addition, MRI of the brain is the investigation of choice in patients with myelopathies that remain unexplained after spinal MRI. However, whether used alone or in combination with other tests, the specificity and predictive value of brain MRI abnormalities for the risk of developing MS, as well as the associated “false positive” rates, remain to be defined by long-term follow-up of prospectively ascertained and representative cases.     

Clinical implications of interictal epileptiform discharges in cognitive functioning in CEC syndrome with evolution into epileptic encephalopathy

In epileptic encephalopathies (EE), interictal epileptiform discharges (IEDs) contribute to cognitive impairment. The EE process has been studied in a patient affected by epilepsy with occipital calcification and celiac disease (CEC syndrome) by combining the administration of brain area stimulus specific (visual and auditory) reaction times (RT) during continuous EEG monitoring with the off-line reconstruction of auditory and visual evoked potentials (EP). Visual RT and VEP were abnormal only if recorded concomitantly to the IEDs. Auditory RT and EP were normal. When the EE process is going on, IEDs transiently disrupt aspects of cortical functioning, contributing to the cognitive impairment.