脑血管病患者经颅磁刺激运动诱发电位的研究

采用经颅磁刺激运动诱发电位（ＭＥＰ）对７２例脑血管病（ＣＶＤ）患者和５０例正常人进行检测。结果：ＣＶＤ患者瘫痪侧上肢磁刺激无反应或皮层潜伏期和中枢传导时间（ＣＭＣＴ）较正常对照组和健侧显著延长（Ｐ＜０．００１）；瘫痪侧下肢磁刺激无反应或ＣＭＣＴ较正常对照组和健侧显著延长（Ｐ＜０．０５）。脑出血与脑梗塞患者ＭＥＰ异常率无显著差异（Ｐ＞０．０５），而与临床病情轻重和病变部位密切相关。提示ＭＥＰ能客观反映ＣＶＤ患者中枢运动传导通路功能受损的情况。     

磁刺激运动诱发电位对S1神经根病的诊断价值

采用硫刺激腰骶部运动神经传导时间（ＭＮＣＴ）与磁刺激Ｇｕｏ窝Ｆ波相结合测定运动神经根传导时间（ＭＲＣＴ）的方法，无痛无创地评估Ｓ１神经根功能。研究对象为５０名正常受试者和３０名Ｓ１神经根受损病人。结果表明：磁刺激ＭＮＣＴ在病人组均正常，而ＭＲＣＴ却明显异常，异常率为８７％，明显高于Ｆ波潜伏期的异常率７３％。因此，磁刺激运动诱发电位（ＭＥＰ）是诊断Ｓ１神经根病的一种有很大应用价值的方法。     

脑血管病患者涨颅磁刺激运动诱发电位的研究

采用经颅磁刺激运动诱发电位（ＭＥＰ）对７２例脑血管病（ＣＶＤ）患者５０例正常人进行检测。结果：ＣＶＤ患者瘫痪侧上肢磁刺激无反应或皮层潜伏期和中枢传导时间（ＣＭＣＴ）较正常对照组和健侧显著延长（Ｐ〈０．００１）；瘫痪侧下肢磁刺激无反应或ＣＭＣＴ较正常对照组和健侧显著延长（Ｐ〈０．０５）。脑出血与脑梗塞患者ＭＥＰ异常率无显著差异（Ｐ〉０．０５），而与临床病情轻重和病变部位密切相关。提示ＭＥＰ能客观反应     

肌肉磁刺激脑诱发电位传入机制的研究

研究磁刺激肌肉脑诱发电位的传入机制。方法对肌松驰下腓肠机ＭＭ－ＳＥＰ及电刺激踝部胫后神经体感诱发电位进行配对对比研究。结果：（１）肌松驰无机收缩时仍可记录到ＭＭＳＥＰ；（２）配对腓肠肌ＭＭＳＥＰ与 胫后神经ＳＥＰＰ４０潜伏期差值伴与不伴肌收缩相差显著；（３）伴肌收空缩时，ＭＭＳＥＰ较配对ＳＥＰＰ４０潜伏期显著延长，不伴肌收时则相差不显著。结论：下沉伴肌收缩时，磁刺激很可能兴奋肌肉运动神经末梢致肌肉     

国人大脑皮层与脊髓电刺激多导联描记MEP正常值

报告国人上、下肢共２４块肌于大脑皮层与脊髓电刺激时的运动诱发电位（ＭＥＰ）正常值。无论上肢或下肢，ＭＥＰ潜伏期均因肌肉所在位置而异，越是远端肌潜伏期越长，认为此乃脊神经长度不同所致，但中枢运动传导时间（ＣＭＣＴ）则与脊神经长度、肢长及身高无关，此为锥体束功能的最重要指标。肌肉轻度收缩时，皮层刺激的ＭＥＰ潜伏期缩短，波幅增高，认为系上运动神经元的易化所致。作者认为，ＭＥＰＲ 多导记录能减少刺激次数，     

短暂性脑缺血发作认知功能与事件相关电位研究

目的：探讨短暂性脑缺血发作（ＴＩＡ）病人事件相关电位（ＥＲＰ）的变化规律及其临床意义。方法：用听觉Ｏｄｄｂａｌｌ刺激序列ＥＲＰ、认知能力筛选试验（ＣＣＳＥ）和简易智力状态试验（ＭＭＳＥ）检测３２例ＴＩＡ病人和３０例年龄、性别、利手和教育程序相匹配的正常人。结果：病人组ＥＲＰ的Ｎ２和Ｐ３峰潜伏期较对照组显著延长，Ｎ２和Ｐ３波幅组均无显著差异、Ｐ３峰潜伏期（Ｐ３ＰＬ）异常率为２５％。病人组ＭＭＳＥ较对     

磁刺激运动诱发电位对脑梗死的辅助诊断价值

目的：研究经颅磁刺激运动诱发电位（ＭＥＰ）对脑梗死的诊断及运动功能的评估价值。方法：对３０例脑梗死患者在急性期行ＭＥＰ检测并对其中１０例患者２月后复查ＭＥＰ，并以３０名健康者为正常对照。结果：急性期ＭＥＰ的异常率９３．３％，主要表现为皮层ＭＥＰ消失，ＣＭＣＴ延长，波形异常及阈刺激强度增高，复查ＭＥＰ１０例中９例有明显改善，结论：ＭＥＰ对脑梗死的临床诊断及运动功能的评估是有价值的。     

经颅磁刺激安全性的实验研究

为证实经颅磁刺激（ＴＭＳ）的安全性，记录并分别分析了大鼠接受ＴＭＳ和头部阳极电刺激（ＥＢＳ）诱发时，后肢肌肉的复合肌肉动作电位（ＣＭＡＰｓ）。发现ＴＭＳ能够在大鼠引发ＣＭＡＰｓ，其阈刺激强度为最大输出的３４．５％，而头旁刺激不能引发ＣＭＡＰｓ；腰椎上方磁刺激可获得潜伏期远短于ＴＭＳ的ＣＭＡＰｓ。麻醉过深可抑制ＴＭＳ引发的ＣＭＡＰｓ。超强ＥＢＳ与ＴＭＳ所诱发的ＣＭＡＰｓ的潜伏期相差１．３ｍｓ。结果表明，ＴＭＳ可在大鼠脑组织中产生足够强度的诱导电流，因而适合于ＴＭＳ安全性的动物实验研究。在此基础上，初步观察了每天５０或１００次的ＴＭＳ连续刺激１～３天，对大鼠行为及脑皮层组织形态及超微结构的影响，发现１００次／天的ＴＭＳ连续作用３天，能够导致大鼠运动皮层产生光镜及电镜下的形态学改变。结果提示，在临床上应注意正确使用ＴＭＳ技术。     

癫痫患者经颅磁刺激运动诱发电位的研究

目的 探讨癫痫患者经颅磁刺激（ＴＭＳ）的运动诱发电位（ＭＥＰ）对癫痫的诊断价值。方法 对３５例癫痫患者和３０例正常对照组的脑运动皮质和第７颈椎和７颈椎水平神经根进行单脉冲磁刺激，引出ＭＥＰ。结果 与对照组比较，两组患者的皮质阈强度均增大，治疗组增大更明显；未治 的皮质潜伏期和中枢神经传导时间缩短，治疗组则无明显改变；三组的周围潜伏期无明显差异。癫痫类型，疗程，联合用药与否以及脑部病灶侧别对ＭＥＰ无     

脑梗死患者的运动及体感诱发电位研究

目的；研究脑梗死患者的运动诱发电位及体感诱发电位改变。方法：对３０例脑梗死患者在急性期行经颅磁刺激ＭＥＰ检测，对其中２０例同时行电刺激ＳＥＰ检测，１０例患者２月后复查ＭＥＰ，并以３０例健康者作为正常对照组。结果；急性期ＭＥＰ的异常率为９３％〈主要表现为皮层ＭＥＰ消失，中枢运动传导时间延长，波形异常及阈刺激强度增高。ＳＥＰ的异常率为３０％，表现为皮层波的缺失及中枢传导时间延长。     

Epidurally recorded spinal cord evoked potentials in patients with cervical myelopathy and normal central motor conduction time measured by transcranial magnetic stimulation.

OBJECTIVE: Use epidural recording of evoked spinal cord potentials (ESCPs) to investigate the pathology of cervical spondylotic myelopathy (CSM) in patients with normal central motor conduction time (CMCT) in upper and lower limbs. METHODS: A total of 75 patients with CSM were studied. All patients were examined before surgery for motor evoked potentials (MEPs) following transcranial magnetic stimulation (TMS). They were also evaluated during surgery by epidurally recorded ESCPs following stimulation of the median nerve, brain and spine. RESULTS: Seven patients (9%) showed normal CMCT in upper and lower limbs upon TMS examination. Only the ESCPs following median nerve stimulation (MN-ESCPs) were abnormal in these patients. In 5 of the 7 patients, a marked block in conduction of MN-ESCPs was observed at the C3-4 intervertebral level. The remaining two patients showed attenuation in the amplitude of MN-ESCPs at mid-cervical levels. CONCLUSIONS: We present 7 cases of CSM with negative CMCT findings. From the MN-ESCP results, we surmise that the pathology of CSM with normal CMCT is due predominantly to dysfunction of sensory systems involved in the upper limbs. SIGNIFICANCE: Examination by TMS is useful in the diagnosis of CSM but the possibility of negative CMCT findings upon TMS must be borne in mind. Multi-functional evoked spinal cord responses demonstrate that lesions in the sensory system are the major underlying pathology.     

Transcranial magnetic stimulation in patients with cervical spondylotic myelopathy: Clinical and radiological correlations

Motor evoked potentials (MEPs) were studied in 28 patients with cervical spondylotic myelopathy. MEPs after cortical stimulation were abnormal in 27 patients, the responses in the leg muscles being affected the most often. Clinically asymptomatic motor lesions were detected in 7 patients (25%). The central motor conduction time (CMCT) for the abductor digiti minimi muscles correlated significantly with the clinical disability, whereas the radiological findings did not correlate with the clinical and neurophysiological parameters. In 9 patients MEPs were also recorded in the biceps muscles. The 7 patients with an abnormal CMCT for the biceps muscles had the most severe stenosis at the C-4–C-5 level or higher. The 2 patients with normal MEPs of the biceps muscles both had a stenosis at the C-5–C-6 level. The results of this study suggest that MEPs are useful for detecting spinal cord dysfunction and for localizing the level of the lesion. Some recommendations regarding the possible use of MEPs in the clinical evaluation of patients with cervical spondylotic myelopathy are given. © 1994 John Wiley & Sons, Inc.     

Transcranial magnetic motor evoked potentials (MEP) and somatic sensory evoked potentials (SEP) in the management of cervical spondylitic myelopathy (CSM)]

Fourteen CSM patients with clinical findings of myelopathy had their diagnoses proved with MRI imaging and at operation. There were a control group of 28 normal subjects for MEP and another control group of 32 for SEP. The results of the study showed that 72.7% had MEP abnormality with prolongation of the central motor conduction time (CMCT) in 7 cases and absence of motor action potentials after C7 stimulation in one of the 11 patients. In 2 patients with prolongation of CMCT, normal SEPs were found in the same arm while 1 patient showed directly a reversal of the results. The short-term follow-up study in 10 patients showed normalization of the prolonged CMCT in one and reappearance of motor action potentials with C7 stimulation in another. The authors considered that the non-invasive and painless, transcranial magnetic stimulation of the motor pathways might be useful in the assessment and management of CSM patients and better than the electrical stimulation.     

Amyotrophic lateral sclerosis versus cervical spondylotic myelopathy: a study using transcranial magnetic stimulation with recordings from the trapezius and limb muscles.

OBJECTIVE: We report an electrophysiological method to differentiate amyotrophic lateral sclerosis (ALS) from cervical spondylotic myelopathy (CSM). METHODS: Motor evoked potentials (MEPs) by transcranial magnetic stimulation were investigated in patients with ALS (n=10) and CSM (n=9). In addition to limb MEPs using the triple stimulation technique (TST) at upper limbs, MEPs recorded from trapezius muscles were compared with those obtained from 23 normal subjects. The parameters studied were: central motor conduction time, amplitude ratio and, for the trapezius, the interside asymmetry. RESULTS: Whereas limb MEPs were abnormal in most ALS and CSM patients (17/19), trapezius MEPs were abnormal in all ALS patients, and normal in 8 out of 9 CSM patients. CONCLUSION: Recording of trapezius MEPs is a valuable addition to the limb MEPs study, since it distinguishes ALS from SCM in most patients.     

Mechanism of prolonged central motor conduction time in compressive cervical myelopathy.

OBJECTIVE: To investigate the mechanism of prolonged central motor conduction time (CMCT) in compressive cervical myelopathy, we compared the calculated CMCT following transcranial magnetic stimulation (TCM) and evoked spinal cord potentials (ESCPs) following transcranial electric stimulation (TCE). METHOD: Motor evoked potentials following TCM were recorded from abductor digiti minimi and abductor hallucis brevis muscles in 16 patients with compressive cervical myelopathy. CMCT was calculated by subtracting peripheral conduction time using peripheral nerve stimulation from MEP latency. ESCPs following TCE were recorded intraoperatively from posterior epidural space. RESULTS: CMCT was prolonged and significant attenuation of the ESCP amplitude following TCE was observed in all patients with cervical myelopathy. In 8 of 16 patients CMCT was significantly prolonged but ESCPs were recorded at the C6-7 level with normal negative peak latency. CONCLUSIONS: Prolonged CMCT may occur with only a minor amount of conduction slowing in the corticospinal tract in compressive cervical myelopathy. Impaired temporal summation of multiple descending potentials following TCM produced delays of motor neuron firing that contribute to the mechanism of prolonged CMCT.     

Preservation of central motor conduction in patients with spinal muscular atrophy type II

We evaluated the central (motor cortex to C8 motoneuron) and peripheral (C8 motoneuron to the muscle) motor conduction in 14 limbs of 7 patients with the intermediate form of spinal muscular atrophy (SMA II). The central motor conduction time (CMCT) was calculated using motor evoked potentials (MEPs) by transcranial magnetic stimulation and the results of a conventional F wave study. Peripheral conduction abnormality was found in 6 median nerves (43%) and 10 ulnar nerves (71%). Even in these patients with peripheral conduction abnormalities, the CMCT was consistently normal whenever the MEP was recorded. These results indicate that the motor conduction of the corticospinal fibers remains normal in SMA II.     

Magnetic stimulation study in patients with myotonic dystrophy

To further define motor nervous system alterations in myotonic dystrophy (MD), motor potentials to transcranial and cervical magnetic stimulation (MEPs) were recorded from the right abductor pollicis brevis muscle in 10 patients with MD and in 10 healthy controls. Cortical and cervical latencies, central motor conduction time (CMCT), stimulus threshold intensity and cortical MEP amplitudes expressed both as absolute values and as %M were analysed. MEP cervical latency, absolute or relative amplitude and excitability threshold did not significantly differ in patients and controls. The mean cortical motor latency and CMCT were significantly prolonged in MD patients with respect to normal subjects. Moreover, CMCTs were found to be significantly related to stimulus threshold intensity (P=0.03) and only marginally related to absolute cortical amplitude (P=0.06). These findings are indicative of a central motor delay, also related to decreased excitability of motor neurons, in patients with MD. No correlations were found between individual neurophysiological parameters and age, duration of disease and clinical impairment. Our results suggest that magnetic stimulation studies can detect subclinical dysfunctions of the central motor system in MD patients, as one of the multisystemic manifestations of the disease, rather independent of the primitive muscle damage.     

A transcranial magnetic stimulation study for the investigation of corticospinal motor pathways in children with cerebral palsy

The aim of this study is to perform transcranial magnetic stimulation (TMS)-based investigation of corticospinal motor pathways in children with cerebral palsy (CP) secondary to hypoxic-ischemic encephalopathy (HIE). TMS parameters including motor evoked potentials (MEPs) and central motor conduction time (CMCT) were recorded in 38 children with CP and 46 age-matched healthy controls. The z-score of MEPs were analyzed with respect to the types of MRI patterns of cortical involvement in children with CP. MEP latency values were correlated with the weight and height of children and to reflect the maturation of the corticospinal pathway. TMS evoked MEPs with prolonged onset latencies in 64% of children with CP while 10% of the CP group failed to elicit MEPs. Related with the MRI pattern, multicystic encephalomalacia (89%) was associated with the highest rates of abnormal cortical MEPs, as followed by periventricular leukomalacia (80%), basal ganglia involvement (66%) and focal cortical involvement (60%) patterns. Children with CP as compared with healthy controls had similar CMCT values on the upper and lower extremities in children with all cortical MR patterns. MEP abnormalities with TMS were consistent with the extent of motor cortex lesions on MRI patterns in CP children with HIE.     

Facilitation and reciprocal inhibition by imagining thumb abduction.

It is well known that motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) of the motor cortex are facilitated by voluntary muscle contraction. We evaluated the effects of imagination of movements on MEP latencies of agonist and antagonist muscles in the hand using TMS. Twenty-two healthy volunteers were studied. TMS delivered at rest and while imagining tonic abduction of the right thumb. MEPs were recorded in response to magnetic stimulation over the scalp and cervical spine (C7-T1), and central motor conduction times (CMCT) were calculated. MEPs were recorded from right abductor pollicis brevis muscle (APB) and adductor pollicis muscle (AP) simultaneously. Imagination of abduction resulted in a shortened latency of MEPs in the APB muscle, and a prolonged latency in the AP muscle. But the imagination caused no significant change in the latency of MEPs elicited by stimulation over the cervical spine. The changes of the CMCT may account for these latency changes with imagination of movement. These findings indicate that imagination of thumb abduction facilitates motoneurons of agonist muscle and has an inhibitory effect on those of antagonist muscle (reciprocal inhibition).     

Significant correlation between corticospinal tract conduction block and prolongation of central motor conduction time in compressive cervical myelopathy

We examined the relationship between the CMCT and features of spinal cord evoked potentials (SCEPs) among 25 patients with compressive cervical myelopathy to elucidate the mechanism underlying the prolonged central motor conduction time (CMCT) in patients with compressive cervical myelopathy. CMCT values were calculated by measuring motor evoked potentials from the abductor digiti minimi muscles (ADMs) and abductor hallucis muscles (AHs) following transcranial magnetic stimulation and peripheral conduction times determined in the ulnar and tibial nerves. SCEPs following transcranial electrical stimulation were recorded intraoperatively from C2-3, C6-7 and T11-12. The shorter/longer CMCTs between the patients' right and left ADMs and AHs were 9.5+/-3.2/11.5+/-3.8 and 16.2+/-2.8/18.8+/-3.3 ms, respectively (mean+/-SD). The percentage ratio of the amplitude of the D-wave at C6-7 or T11-12 to that at C2-3 was 19.4+/-14.2 or 3.2+/-3.1%, respectively. The CMCT value was significantly correlated with the attenuation of SCEP amplitude, but not with SCEP latency both at C6-7 and T11-12, suggesting that CMCT prolongation is primarily due to corticospinal conduction block rather than conduction delay. Spinal motor neurons might need more time to fire in patients with compressive cervical myelopathy when corticospinal potentials, but not conduction, are attenuated, thereby resulting in prolonged CMCT.