正中神经SEP与偏瘫手功能相关研究

目的通过检测偏瘫患者正中神经体感诱发电位(SEP),并评估患侧手Brunnstrom分级,观察正中神经SEP作为评测偏瘫手功能客观指标的可靠性,为临床判断偏瘫手功能提供客观依据.方法27例住院偏瘫患者,测定双侧正中神经SEP,根椐Kovindha标准将正中神经SEPN20进行分级.按Brunnstrom分级对偏瘫手进行评定.将患侧正中神经SEPN20分级与患侧手Brunnstrom分级进行Spearman等级相关分析.结果正中神经SEP等级分级与手Brunnstrom评定分级呈正相关,相关系数r＝0.6295,P＜0.01有相关性意义.结论正中神经SEP可以作为临床判定手功能的一个敏感的电生理指标.SEP为偏瘫手功能的评定及康复治疗提供了有价值的依椐.     

体感诱发电位在神经性瘫痪中的定位价值

目的检测及分析小儿神经性瘫痪体感诱发电位(SEP),探讨SEP在小儿神经性瘫痪定位诊断中的价值。方法以180例0～14岁小儿刺激正中神经和胫后神经体感诱发电位正常值为标准,对临床有肢体瘫痪的335例年龄49d～13岁小儿的体感诱发电位进行分析比较。结果266例临床有痉挛性肢体瘫痪小儿,SEP异常率共为86.5%(230/266)。表现为脊髓和/或皮层SEP峰潜伏期记录延长或消失,而周围神经电位正常;脊髓疾病及脑性瘫痪SEP异常率较其他中枢神经疾病高,分别为92.6%(25/27)和86.3%(139/161);颅内病变中天幕上SEP异常较天幕下常见;69例临床周围性肢瘫SEP异常率20.3%(14/69);3岁以下年龄组与3岁以上年龄组之间异常率差异意义无显著性。结论体感诱发电位对小儿肢体瘫痪定位,特别是对临床工作中较难判断的小婴儿瘫痪定位诊断具有实用价值。     

Median nerve somatosensory evoked potentials in migraine.

Eur J Neurol. 2002;9:227-232.
In visual evoked potential studies, habituation during stimulus repetition with the same stimulus at a constant intensity has been found to be abnormal in migraineurs between attacks. The purpose of this study was to investigate habituation of somatosensory evoked potentials (SEPs) and the effects of migraine on them. Eighty-five subjects were included in the study: 30 healthy volunteers (HVs) and 55 migraineurs [30 with migraine without aura (MO), 25 with migraine with aura (MA)]. During continuous stimulation at 3 Hz, four blocks of 100 responses were sequentially averaged of Erb's point (N9), cervical (N13), and cortical (N20) median nerve SEPs. Mean amplitude changes in the second, third and fourth blocks are expressed as percentages of the first block. There was habituation to N13 and N20 in the second, third and fourth blocks in HVs. In the migraine groups, there was no habituation; on the contrary, potentiation was found. This potentiation was statistically significant only in the second blocks for N13 (MO P   =  0.007, MA P   =  0.01 versus HVs). However, in both migraineur groups, the rate of N20 potentiations was statistically significant versus that in HVs for all blocks (all P < 0.05). It is concluded that whilst physiological habituation occurs in HVs for cervical and cortical SEPs, in migraine patients there is an interictal deficit of habituation of this sensory modality.
Comment: This interesting study confirms the lack of habituation to repetitive stimuli reported in migraineurs between attacks and extends this finding to somatosensory evoked potentials using median nerve stimulation. One might speculate that migraineurs lack a protective mechanism which modulates both cervical and cortical sensory inputs. DSM     

Comparison of median and posterior tibial nerve somatosensory evoked potentials in ambulatory patients with definite multiple sclerosis

Somatosensory evoked potentials (SEPs) were recorded for stimulation of both median nerves and both posterior tibial nerves in control subjects and in subjects with multiple sclerosis (MS) of several years' duration, who were ambulatory and not experiencing exacerbation. Documentation of peripheral nerve conduction revealed no abnormalities in any of the subjects. Centrally, abnormal responses to median and posterior tibial nerve stimulation were found at the spinal level and/or the scalp in nearly all MS patients. Using the latency of the initial negativity of scalp SEPs, posterior tibial SEPs were abnormal significantly more often than median SEPs. Calculations suggested a significant increase in spinal conduction time. The high incidence of abnormal SEPs does not support any substantial physiological recovery in this group of MS patients.     

Tibial nerve somatosensory evoked potentials in spinal cord hemisection

Somatosensory evoked potentials (SEPs) have been studied in many disease states since they were first described by Dawson in 1947. However, there have been very few reports of SEP findings in patients with spinal cord hemisection. On the basis of clinical correlation, Giblin first postulated that the activity giving rise to the initial cortical components of the SEP travels through the dorsal column-lemniscal system. However, the pathway through which these evoked potentials are transmitted has recently been questioned. This paper examines the results of tibial nerve SEPS performed on four patients with spinal cord hemisection (Brown-Séquard syndrome). In all four cases presented, the impairment of cortical SEP components was consistently associated with stimulation of the leg ipsilateral to the side of cord injury. We conclude that the most likely mechanism of transmission is through the ipsilateral dorsal columnlemniscal system.     

正中神经短潜时体感诱发电位分析指标临床应用的对比研究

目的探讨正中神经短潜时体感诱发电位（ｍｅｄｉａｎｎｅｒｖｅｓｈｏｒｔｌａｔｅｎｃｙｓｏｍａｔｏｓｅｎｓｏｒｙｅｖｏｋｅｄｐｏｔｅｎｔｉａｌ,ＭＮＳＬＳＥＰ）分析方法。方法用多功能生理反应记录仪对１３０名健康人及６２例单侧大脑半球缺血性完全性卒中患者和３０例地方性克汀病患者进行ＭＮＳＬＳＥＰ测定。结果ＮＴ＋Ｗ测算法克服了现今国际公认的ＭＮＳＬＳＥＰ分析指标Ｎ２０Ｎ９、Ｎ２０Ｎ１３受个体身高及周围神经传导速度（ｐｅｒｉｐｈｅｒａｌｎｅｒｖｅｃｏｎｄｕｃｔｉｏｎｖｅｌｏｃｉｔｙ,ＰＮＣＶ）差异影响,其变异系数较Ｎ２０Ｎ９、Ｎ２０Ｎ１３小;可显著降低假阴性及假阳性病例的发生。结论采用ＮＴ＋Ｗ＝Ｎ２０－１．３１Ｎ９公式作为ＭＮＳＬＳＥＰ的分析指标,可明显提高ＭＮＳＬＳＥＰ临床应用的准确性     

Itching-related somatosensory evoked potentials

Electrically evoked itching has the strong potential to be used to investigate the central processing associated with itching at high temporal resolution by employing magnetoencephalography, electroencephalography (EEG), and event-related functional magnetic resonance imaging. However, it has not been investigated whether time-locked brain activity can be measured using this stimulus, and whether the itching sensation induced by electrical stimulation of the skin is associated with C-fibers. Thus, we investigated these problems in this study. Itching sensations were elicited when electrical stimuli were applied to the skin of the right wrist and right forearm. EEG activity was recorded from 5 electrodes (Fz, FCz, Cz, CPz and Pz). When the right wrist was stimulated, the reaction time (RT) and latency of the positive component of somatosensory evoked potentials (P1) were 1215 ms and 963 ms, respectively. When the right forearm was stimulated, the RT and peak latency of the P1 were 1013 ms and 772 ms, respectively. The conduction velocity estimated from the RT and latency of the P1 was 1.04 m/s and 0.92 m/s, respectively. In addition, the itching sensation and P1 were inhibited when the current intensity was increased into the range eliciting pain and touch sensations, implying interaction between C- and A-fibers. These findings demonstrate that time-locked brain activity can be measured using electrically evoked itching and that the itching sensation induced by the electrically evoked itching is associated with C-fibers. Thus, this method is useful for research into the central processing of itching.     

Bilobed splitting of median nerve somatosensory evoked p14 potential under deep hypothermia

Objective.To further elucidate temperature related changes in subcortical components of somatosensory evoked potentials (SEP) in intraoperative monitoring. Methods.Intraoperative monitoring of subcortical median nerve SEP under deep hypothermia is described in a patient undergoing intracranial giant aneurysm surgery. The P14 potential was recorded from Fz-Pgz (front to nasopharynx). Results.At a body core temperature of less than 17 °C, P14 showed a bilobed splitting that was reversible with rewarming. A comparison with latencies of other subcortical potentials of presynaptic and postsynaptic origin, recorded at the neck, speaks in favor of a presynaptic generation of the first P14 wave and a postsynaptic origin of the latter P14 wave. Conclusions.Deep hypothermia may separate presynaptic and postsynaptic electric activity of evoked potentials that overlap at normal body temperature. Such possible phenomena must be kept in mind to correctly interprete monitoring data at very low body temperatures and may help in better understanding the generation of different SEP components.     

脑干听觉诱发电位和体感诱发电位对昏迷患者预后的判断

目的脑干听觉诱发电位(BAEP)和体感诱发电位(SEP)与昏迷患者预后密切相关,探讨BAEP和SEP判断昏迷患者脑功能状态的可行性和准确性。方法采用丹麦Dantec公司生产Neuromatic2000型肌电图诱发电位仪。检查ICU病房中36例昏迷患者的BAEP和SEP。BAEP分析III-V波,SEP分析P15、N20、P25波。检查结果分为正常和异常。预后分为好转和死亡。结果36例患者,BAEP正常12例,异常24例。SEP正常13例,异常23例。好转13例,死亡23例。当SEP异常时,死亡率明显高于SEP正常时。而同时伴有BAEP异常时,死亡率更高。14例患者SEP检查P15、N20、P25波均消失,12例死亡,病死率为86%。5例患者BAEP检查III-V波和SEP检查P15、N20、P25波均消失,全部死亡,病死率为100%。结论BAEP和SEP的正常与否与昏迷患者的预后有密切关系(P=0.011)。SEP异常是判定的主要根据。BAEP和SEP相结合,则可以提高判断的准确性。对昏迷患者进行动态的BAEP和SEP观察可提高判断的准确性。     

Fundamental principles of somatosensory evoked potentials

Studies of SSEP provide unique opportunities for investigating physioanatomic substrates of sensory pathway and cognitive functions of the sensory system. Progress of clinical investigation and application of SSEP have been stalled in more recent years, although SSEP still remain a useful tool for diagnosis of various neurologic disorders and for the monitoring of spinal cord function during surgery. Reflecting complex sensory system in human, scalp-recorded SSEP consists of multiple waves, having different distribution, amplitude, and latencies among different electrodes. The physioanatomic significance of these multiple waves, especially the late components, is largely unknown. These should be explored further, especially in relation to cognitive function.     

Alternative anterior reference sites for measuring posterior tibial nerve somatosensory evoked potentials

Objective  

The purpose of this study was to examine the utility and feasibility of using alternative anterior reference leads when measuring left posterior tibial nerve somatosensory evoked potentials (SEPs).     

正中神经短潜时体感诱发电位分析指标-NT＋W测算公式的研究

目的探讨从正中神经短潜时体感诱发电位（ｍｅｄｉａｎｎｅｒｖｅｓｈｏｒｔｌａｔｅｎｃｙｓｏｍａｔｏｓｅｎｓｏｒｙｅｖｏｋｅｄｐｏｔｅｎｔｉａｌ，ＭＮＳＬＳＥＰ）测算人体平均突触延搁时间的方法。方法用多功能生理反应记录仪对４３０名健康人进行ＭＮＳＬＳＥＰ测定，并应用ＮＴ＋Ｗ＝Ｎ２０－１．３１Ｎ９公式计算其平均突触延搁时间。结果应用公式计算出的人体突触延搁时间及其变化规律完全符合突触传递的电生理学特性。结论ＮＴ＋Ｗ测算法具有重要的理论及临床应用价值。     

Investigation of the inter-observer variability effect on the prognostic value of somatosensory evoked potentials of the median nerve (SSEP) in cardiac arrest survivors using an SSEP classification

Background and purpose

We investigated the inter-observer variability in interpretation of median nerve SSEPs with regard to neurological prognosis in survivors of cardiac arrest (CA).

Methods

Four experienced neurologists analyzed 163 median nerve SSEPs on the basis of a pre-defined classification of SSEPs into five patterns (A–E), with consideration of cortical potentials up to a latency of 150 ms. Of these, 133 recordings were from CA survivors and 30 were from healthy volunteers. The experts were blinded to whether a SSEP finding was from a CA survivor or a healthy volunteer. They were also unaware of the neurological outcome for the resuscitated patients. Three categories were defined for decision making. These were “good neurological outcome” represented by patterns A–C, “poor neurological outcome” (patterns D and E), and “not evaluable”. Experts’ agreement was calculated using the kappa-coefficient.

Results

The mean correct prediction by the experts was 81.8% (range 76.3–86.6%) in resuscitated patients with good neurological outcome. In those with poor neurological outcome, however, correct prediction was achieved in only 63% (60.5–66%). All SSEPs from healthy volunteers were classified as “good neurological outcome”. The kappa-coefficient (κ) for all decision-making classifications was 0.75; for patients with poor outcome it was 0.76 and for those with good outcome 0.88. The predictive value for poor neurological outcome of the SSEP pattern D achieved a specificity of 93.5% and that of E a specificity of 98.4%.

Conclusion

Our study demonstrates good inter-observer agreement in the interpretation of median nerve SSEPs in CA survivors on the basis of a pre-defined SSEP evaluation set. The strongest correlation with poor outcome was found for pattern E, bilateral absence of the N₂₀ peak.     

Effects of transcutaneous electrical nerve stimulation and aspirin on late somatosensory evoked potentials in normal subjects

The effects on late somatosensory evoked potentials (SEPs) of transcutaneous nerve stimulation (TENS) and aspirin (600 mg), compared with placebo, were studied in 32 young, healthy male and female volunteers. SEPs were produced by electrical stimulation of the median nerve at moderate, non-painful, intensities. There was a reduction in the peak-to-peak amplitude of the late components N1P2 (N1 latency: 100-160 msec; P2 latency: 160-260 msec) of the SEP in all groups over time. TENS but not aspirin produced further significant changes compared with placebo, including a fall in N1P2 amplitude, an increase in N1 latency, and a decrease in the total excursion of the SEP between 25 and 450 msec after stimulus onset.     

功能性电刺激对健康青年受试者体感及运动诱发电位影响的对照研究

目的：观察功能性电刺激（FES）对健康青年体感诱发电位（SEP）及运动诱发电位（MEP）的影响。方法：采用经颅磁刺激仪（TMS）及肌电图仪,分别测量15例健康青年,其中男10例,女5例,平均年龄（22.9±0.7）岁。单次FES前、后检测SEP值及MEP值,其中11例完成两周FES（每天1次,每次30min）,并再次接受SEP及MEP检测。结果：健康青年者单次及2周FES后SEP及MEP值的潜伏期缩短,波幅增高,与FES前比较,差异有显著性意义;非FES侧变化不明显。结论：健康青年者FES前后SEP及MEP值均有变化,尤以波幅明显。     

Lateral femoral cutaneous nerve conduction v somatosensory evoked potentials for electrodiagnosis of meralgia paresthetica.

The aim of this study is to compare sensory nerve conduction with somatosensory evoked potentials of the lateral femoral cutaneous nerve to determine which is the most reliable electrodiagnostic method to assess meralgia paresthetica. Thirty patients with unilateral clinically defined meralgia paresthetica and 30 controls were studied with both methods. The main outcome measures were sensory action potential side-to-side amplitude ratio, somatosensory evoked potentials side-to-side latency difference, and side-to-side amplitude ratio. Sensory nerve conduction was abnormal in all patients: only four participants had abnormal somatosensory evoked potentials with double derivation (Fz/Cz and Ci/Cc) recording, and eight participants had abnormal findings with Fz/Cz derivation. Overall, this study demonstrates that sensory nerve conduction is the more reliable method for meralgia paresthetica electrodiagnosis. In fact, only very serious nerve damage regularly induces abnormal somatosensory evoked potentials, which is not recommended for routine electrodiagnostic study of meralgia paresthetica.     

脑梗死患者非梗死侧正中神经体感诱发电位的研究

目的观察脑梗死患者非梗死侧正中神经体感诱发电位(SEP)的改变。方法对25例经头部MRI确诊的单侧颈内动脉脑梗死患者进行正中神经体感诱发电位检测并与正常对照组进行比较。结果脑梗死组与对照组比较,非梗死侧SEP的P15潜伏期延长(P<0.05)、N60潜伏期显著延长(P<0.001);25例脑梗死患者中8例患者非梗死侧SEP异常,异常率32%。结论SEP检测对发现脑梗死患者的微小病灶或亚临床病灶具有重要价值,其敏感性高于MRI。它是一种客观的、敏感的脑功能评定方法。     

The effects of unilateral transcutaneous electrical nerve stimulation of the median nerve on bilateral somatosensory thresholds

Transcutaneous electrical nerve stimulation (TENS) is used to relieve acute and chronic pain. TENS electrodes are applied at the site of pain or in segments related to the pain, although there is limited research to support either approach. This study investigated the effects of unilateral TENS on mechanical and thermal thresholds at ipsilateral and contralateral sites in healthy human participants. Sensory perception thresholds were measured on the ipsilateral and contralateral thenar eminence of 16 volunteers for von Frey filaments, sharpness, warm, cold and heat pain. TENS was administered over the right median nerve for 10 min at 100 pulses per second (pps) and an intensity which elicited mild tingling in the hand. During TENS, ipsilateral threshold was greater than contralateral threshold for all sensory modalities, although differences were less marked for thermal stimuli. TENS effects had disappeared 30 min after TENS had been switched off although there was a tendency for thermal thresholds to remain elevated. We conclude that during stimulation, TENS elevates somatosensory thresholds within the distribution of the stimulated nerve. The rapid and short-lived ipsilateral effect is consistent with findings from animal studies and suggests a central segmental mechanism.     

经皮电神经刺激不同部位对脑卒中患者体感诱发电位的影响

目的比较单次（45min）经皮电神经刺激（TENS）不同部位治疗脑卒中患者患侧肢体对体感诱发电位（SEP）的影响。方法按TENS的治疗部位将14例脑卒中患者分为2组：同时刺激偏瘫侧上、下肢组（上下肢组）8例和单独刺激偏瘫侧上肢组（上肢组）6例。2组患者分别接受1次45min的TENS治疗，刺激频率为100Hz，脉宽为200μs，强度为患者最大耐受量。分析双侧上、下肢或双上肢SEP检测过程中N9和N20的波幅及潜伏期，比较同一测试时间点SEP的重复检测信度，并比较两种不同治疗方法所得到的SEP结果差异。结果2组患者2次检测的SEP值等级间相关系数（ICC）值为0．9006—1．0000，上肢组优于上下肢组。治疗前、后比较，上下肢组的N9和N20波幅及潜伏期无明显变化，而上肢组N9及N20波幅增高，潜伏期缩短，以N20的改变更为显著。治疗前2组患者SEP值比较，差异有统计学意义（P〈0．05），故以治疗前SEP值为协变量进行统计学分析，治疗后2组患者SEP值差异有统计学意义（P〈0．01）。结论单次45min的TENS治疗能改善脑卒中患者偏瘫肢体的SEP值，单独刺激上肢或同时刺激上下肢均有较高的可重复性，但单独刺激上肢的方法可重复性更高，SEP值的改变更明显。     

功能性电刺激对脑卒中患者体感诱发电位影响的信度研究

目的：研究功能性电刺激（FES）治疗脑卒中患者患侧肢体对体感诱发电位（SEP）的影响及SEP的重复测试信度。方法：按FES的治疗部位将9例脑卒中患者按入院时间顺序随机分为刺激偏瘫侧上肢组（上肢组）4例和刺激偏瘫侧下肢组（下肢组）5例。2组患者分别接受1次30min的患侧上肢或下肢FES治疗,刺激频率为30Hz,脉宽为0.2ms,通电/断电比为5s/5s,波升/波降为1s/1s,刺激强度为患者耐受的最大强度。2组患者在治疗前后分别接受双侧上肢或下肢的SEP检测。分析双侧上肢或双侧下肢SEP检测过程中N9、N20和P40的波幅及潜伏期,并比较同一测试时间点SEP的重复检测信度。结果：2组患者2次检测的SEP值等级间相关系数（ICC）值上肢为0.989—1.000,下肢为0.832—1.000,上肢组优于下肢组。治疗前后SEP值比较,治疗后上肢组双侧N9、N20的波幅均升高,健侧N20的潜伏期缩短。下肢组患侧N9、P40的波幅和健侧P40的波幅均升高,健侧N9的波幅下降。结论：利用SEP检测脑卒中后肢体接受FES治疗的神经电生理变化具有较高的信度,且上肢组优于下肢组。