Jitter测定在评价重症肌无力病情严重程度中的意义

目的:探讨Jitter值对判断重症肌无力(MG)病情及预后的意义。方法:运用单纤维肌电图(SFEMG)技术对49例不同病情、病型及治疗的MG患者进行Jitter值测定,同时测定每一例的临床绝对评分。结果:(1)临床绝对评分、Jitter各指标与病型均有关,且Jitter各指标对区分眼型(Ⅰ)和全身型(Ⅱ)有所帮助;(2)MG患者个体MCI)均值、＞55μs电位对百分比及阻滞电位对百分比与临床绝对评分之间呈显著负相关(P＜0.001),而正常电位对百分比与临床绝对评分之间存在显著正相关(P＜0.001);(3)病程与Jitter各指标之间均无相关性(P＞0.05);(4)短期随访经激素治疗或手术治疗后乙酰胆碱受体抗体(AChRab)有转阴趋势,而SFEMG和低频重复电刺激检查结果转阴趋势不明显。结论:Jitter值测定是一项评价重症肌无力病情严重程度较为客观、准确的技术。     

单纤维肌电图在68例运动神经元病患者中的研究

目的　研究运动神经元病 (MND)患者的单纤维肌电图 (SFEMG)改变、病理生理机制及临床意义。方法　对 6 8例 (男 4 3例 ,女 2 5例 )经病史、临床表现和神经电生理检查测定证实的MND患者进行了伸指总肌SFEMG测定 ,并与年龄匹配的正常人对照。结果　所有患者感觉神经传导速度测定均正常 ,肌电图为广泛神经源性损害。SFEMG检查发现 :颤抖值 (jitter)为 30～ 178μs,平均 (80 2± 32 6 ) μs ;jitter>5 5 μs占 5 0 %～ 10 0 0 % ,平均 6 0 6 %± 2 9 0 % ;阻滞 (block)所占百分比为 0 0 %～90 0 % ,平均 2 9 3%± 30 0 % ;纤维密度 (FD)为 1 4～ 4 0 ,平均 2 6± 0 6。其中 5 1例确诊和拟诊的肌萎缩侧索硬化患者jitter增宽、block和FD增高最明显。还发现伸指总肌肌无力的程度与jitter增宽和block百分比呈明显的负相关。结论　SFEMG的异常改变在确诊患者组最明显 ;jitter增宽、block百分比升高和FD增高与肌肉无力的严重程度呈明显的负相关 (P <0 0 0 1) ;jitter增宽、block百分比升高和FD增高反映进行性失神经、神经再生和神经肌肉接头处的传递情况     

重症肌无力非神经肌肉接头处电生理改变的研究现状

重症肌无力（Myasthenia gravis，MC）是一种神经肌肉接头（NMJ）处乙酰胆碱（Ach）传递障碍的自身免疫性疾病，电生理检查表现为重复神经电刺激（RNS）及单纤维肌电图（SFEMG）等的异常。但是，近年来研究发现MG患者伴有多种中枢神经系统（CNS）损害的电生理改变，表现为脑电活动、视觉诱发电位、脑干听觉诱发电位、体感诱发电位检查等的异常。另外，Gibson等提出MG患者还存在心脏损害的电生理变化，表现为心电图的异常改变。现将电生理技术在MG非NMJ处的研究现状综述如下。     

RNS与SFEMG在检测ALS患者神经肌肉接头功能紊乱的比较研究

目的探讨重复神经电刺激(RNS)与单纤维肌电图(SFEMG)在检测肌萎缩侧索硬化(ALS)患者神经肌肉接头功能紊乱中的吻合率及RNS低频递减阳性率与SFEMG指标纤维密度(FD)、颤抖(jitter)、阻滞(block)的关系。方法收集2008-5—2009-4在北京协和医院神经科门诊或病房确诊或拟诊的ALS患者43例,同时行RNS及SFEMG检查。比较RNS与SFEMG在判断ALS患者神经肌肉接头紊乱的敏感性和特异性,并分析RNS低频递减与SFEMG参数指标jitter、block、FD的相关性。结果(1)43例患者中26例RNS(+),占60.5%,17例RNS(-),占39.5%。SFEMG(+)34例,占79.1%,SFEMG(-)9例,占20.9%。其中SFEMG(+)+RNS(+)者共25例,SFEMG(-)+RNS(-)者8例。RNS在判断ALS存在神经肌肉接头受累方面与SFEMG比较有一定的吻合性(Kappa=0.47,P0.01)。(2)RNS阴性和阳性组FD间比较无统计学差异(t=-0.1405,P0.05)。RNS阳性组Block程度明显高于RNS阴性组(χ~2=11.432,P0.01),jitter值也明显高于RNS阴性组(t=2.906,P0.01)。桡神经RNS波幅递减程度与jitter值呈正相关(r=0.626,P0.05)。结论 RNS与SFEMG比较有一定的吻合率。RNS检查灵敏度较高,具有操作简单,费用低,耗时短,无创,不需患者特殊配合,近远端肌肉均可操作,易于推广的特点,对ALS患者的辅助诊断具有意义。     

重症肌无力单纤维肌电图测定

57例MG患者和40例健康正常人分别进行了SFEMG检查,部分患者同时进行重复电刺激和SFEMG进行比较。结果发现:MG患者SFEMG阳性率为82.5％。按MG分型:眼肌型阳性率为58.3％,全身型阳性率为100％。而重复电刺激阳性率仅为64％。同时SFEMG的个体MCD均值大小及Jitter阻滞率与病程无关,与病型和病情有关。SFEMG是诊断MG敏感的电生理检查方法。     

单纤维肌电图对糖尿病周围神经病的诊断价值

目的 探讨单纤维肌电图（SFEMG）在糖尿病周围神经病（DPN）中的应用。方法 采用Viking Ⅳ肌电图仪,测定36例2型糖尿病患者指总伸肌的颤抖和纤维密度（FD）,同时进行常规神经传导检测（NCS）并测量空腹血糖和糖化血红蛋白（HbA1C)。结果 颤抖和FD具有相关性,且均与HbA1C呈正相关。18例NCS异常者,颤抖值均超过正常范围（11例伴阻滞）,14例FD增加;18例NCS正常者,7例颤抖值增大（3例伴阻滞）,5例FD增加。结论 颤抖和FD所反映的失神经－神经再支配与代谢状况相关联;SFEMG是DPN早期诊断的敏感手段,可发现糖尿病亚临床周围神经病变。     

重症肌无力患者眼轮匝肌单纤维肌电图检测

目的 探讨重症肌无力患者眼轮匝肌单纤维肌电网(SFEMG)检查的临床应用价值.方法 40例重症肌无力患者(眼肌型27例,全身型13例)分别接受眼轮匝肌单纤维肌电图[以平均颤抖值>正常值上限、>10%单个肌纤维对颤抖增宽(>55μs)、伴或小伴阻滞作为异常颤抖判断标准]和面神经重复神经电刺激(RNS)检查(以复合肌肉动作电位衰减>15%作为异常动作电位判断标准),比较两种电生理学检查方法的阳性检出率、敏感性和特异性,以及SFEMG测值与重症肌无力分型之间的关系.结果 重症肌无力患者眼轮匝肌平均颤抖值为(76.42±24.59)μs,颤抖增宽电位对比例(69.01±26.66)%,阻滞电位对比例(46.62±27.41)%,与对照组比较差异具有统计学意义(均P<0.05).SFEMG阳性检出率为82.50%(33/40),高于RNS(35%,14/40),差异具有统计学意义(P<0.05).SFEMG检查敏感度分别为82.50%和77.50%,特异度均为100%;RNS检查敏感度分别为27.50%和22.00%,特异度均为0.结论 眼轮匝肌单纤维肌电图是诊断重症肌无力较为敏感的电生理学检查方法,应用于临床时尚需与其他肌肉单纤维肌电图检查、重复神经电刺激检查及乙酰胆碱受体抗体试验相结合.     

伴与不伴甲状腺功能亢进重症肌无力患者的临床资料比较研究

目的探讨伴与不伴甲状腺功能亢进重症肌无力(MG)患者在临床、神经电生理特点以及血清乙酰胆碱受体(ACh R)抗体滴度等方面的差异。方法以39例MG伴甲状腺功能亢进的患者为MG+甲亢组,39例单纯MG患者为对照组。比较两组患者的临床、神经电生理特点以及血清ACh R抗体滴度等方面的差异。结果初诊时MG+甲亢组与对照组比较,美国重症肌无力协会分型为Ⅰ型者更多见(P=0.005);低频重复电刺激检测眼轮匝肌-睑部肌肉复合肌肉动作电位波幅的衰减幅度降低(P=0.005);血清ACh R抗体滴度降低(P=0.020)。MG+甲亢组MG定量评分、MG徒手肌力测试、MG日常活动量表、MG疾病相关生存质量简表和汉密尔顿抑郁量表评分显著低于对照组(P0.05)。结论 MG伴甲状腺功能亢进患者总体临床症状较轻,与单纯MG患者相比存在明显异质性。     

胆碱酯酶抑制剂对重症肌无力电生理学检查结果的影响

目的探讨胆碱酯酶抑制剂对重症肌无力(myasthenis gravis,MG)电生理学检查结果有无影响。方法对53例MG肌注新斯的明1.5 mg,每例均在注射前后依次进行临床绝对评分、右侧伸指总肌的单纤维肌电图(single fiber electromyography,SFEMG)和左侧桡神经低频重复电刺激(repetitive nerve stimulation,RNS)检查,比较用药前后各项指标的变化。结果发现用药前后SFEMG中平均颤抖(jitter)、异常电位对和阻滞电位对的比例均无统计学差异(P>0.05);与此同时用药后RNS波幅递减的幅度和临床绝对评分均较用药前显著降低(P均为0.000)。结论胆碱酯酶抑制剂对MG的SFEMG的各项指标均无明显影响,而能显著改善RNS结果和临床症状的评分。     

重症肌无力患者血清干扰素-α抗体的检测意义

目的研究重症肌无力（MG）患者外周血中干扰素α抗体（IFN-αAb）的含量,并探讨其与MG的关系。方法采用ELISA法测定60例MG患者、20例正常对照组（NC）及20例非MG其他神经系统疾病患者（OND）血清中IFN-αAb。结果 发现伴胸腺瘤的重症肌无力患者（MGT）血清中IFN-αAb阳性率为75%,明显高于不伴胸腺瘤的重症肌无力患者（NTMG,11.5%）及对照组（P〈0.05）;晚发型MG者IFN-αAb阳性率为29.41%,明显高于早发型MG患者7.69%（P〈0.05）。结论 伴胸腺瘤的MG患者及晚发型MG患者外周血中IFN-αAb表达增高。     

The miswired goldfish brain: Long-term persistence and transience of retinal projections following tectal lobe removal

Following tectal lobe removal in the goldfish, optic fibers, which are sectioned by the surgery, regenerate through various abnormal pathways to both the optic tectal lobe which remains and to various non-optic sites in the brain. In this communication we present anatomical evidence that regenerated optic fibers in many of these pathways atrophy or disappear within several months after surgery. By contrast, in some pathways the regenerated fibers persist for at least 1.5 years. We suggest that the majority of fibers which persist for long periods do so because they have reached the remaining tectal lobe and been able to make synapses there.The results from this system are briefly compared to those which have been obtained in studies of regeneration in the peripheral nervous system and parallels between the two are noted.     

Single fiber EMG in a neurological department

The use of the method with examination of jitter and fiber density is mentioned. Some patients (one with polyneuritis, one with dystrophia musculorum progressiva and three with myasthenia gravis) are presented, with demonstration of the jitter (the variability of the interpotential interval).
Jitter examinated in musculus extensor digitorum communis was prolonged (over 55 microsec) in patients with myasthenia gravis and dystrophia musculorum progressiva.     

Physiological evidence for branching of peripheral unmyelinated sensory afferent fibers in the rat

Single unmyelinated sensory afferent nerve fibers were recorded in dorsal root filaments in urethane-anesthetized or in decerebrate-spinal rats. The peripheral branch of these axons ran in the sural nerve where they were stimulated by tungsten microelectrodes. All action potentials showed the characteristics of single fiber responses with a fixed all or none shape and a fixed latency at a given stimulus strength. In all units, the action potential evoked from a proximal stimulus site collided with the action potential evoked from a distal stimulus site. Of the 44 single units isolated, 17 showed the expected small progressive decrease of latency of the recorded impulse as the stimulus strength at a fixed point on the sural nerve was progressively raised above threshold. However, in 27 units there was an abrupt jump decrease of latency as the stimulus rose above the threshold. The average size of this latency shortening was 2.2 msec, which occurred as the stimulus strength rose a mean 21% above threshold. As the stimulus rose above threshold, 7 fibers showed 3 different fixed latencies and 2 fibers showed 4 fixed latencies. In order to test the possibility that the peripheral nerve contained 2 branches of the same axon with one conducting slower than the other, the peripheral nerve was stimulated at progressively longer conduction distances. As predicted, the difference between the 2 fixed latencies became larger as the conduction distance increased. We discuss 6 possible explanations for the results and conclude they are consistent with the proposals that some fibers branch distal to the dorsal root ganglion and some branches do not establish a functional sensory ending in the periphery.     

Differentiation between single fiber potentials from one muscle fiber or contaminated by other fibers using discriminating function

ObjectivesThe aim was to improve the identification of potentials recorded using single fiber electromyography (SFEMG) contaminated by potentials from other muscle fibers, which might affect measured jitter value, by defining more selective criteria of single fiber potential (SFP) discrimination. We were looking for solutions suitable for automatization.MethodsStandard parameters characterizing SFP and their combinations were analyzed to define an analytical discriminating function able to verify if potentials recorded using SFEMG are due to single fiber or due to two (or more) fibers.ResultsThe discriminating function is based on combination of standard SFP parameters. The procedure was tested on a set of simulated i.e., known data and on samples of clinical data. The tests on simulated data confirmed assumed properties of discriminating function. Preliminary results of pilot studies using patient data suggest its ability for differentiation between potentials of one fiber and contaminated ones. The procedure is suitable for automatization.ConclusionResults suggest that proposed discriminating function when supplementing standard criteria would help to promote SFP recordings and enable to improve relevancy of jitter measurements and of jitter value norms.     

Is there a reciprocal connection between the red nucleus and the interposed cerebellar nuclei? Conclusions based on observations of anterograde and retrograde transport of peroxidase-labelled lectin in the same animal

The rubrointerposital projection was studied in cats where wheat germ agglutinin-horseradish peroxidase (WGA-HRP) was implanted in various parts of the interposed nuclei. No retrogradely labelled rubral cells were observed following implantations in the posterior interposed nucleus, and only very few such cells were identified in the contralateral red nucleus after implantations restricted to the anterior interposed nucleus with no contamination of cerebellar white matter or cortex. However, when WGA-HRP was delivered by a pressure injection, which in addition to the anterior interposed nucleus included the adjacent white cerebellar matter along the needle track and the overlying cortex, many retrogradely labelled cells were present contralaterally in the magnocellular red nucleus, with some also found in its rostral parvicellular part. The same observation was made when injection of free HRP exceeded the boundaries of the anterior interposed nucleus. These observations indicate that there is a negligible projection from the red nucleus to the contralateral interposed cerebellar nuclei. What has been considered to be rubrointerposital cerebellar fibres probably is the projection to the cerebellar cortex (Exp. Brain Res., 50 (1983) 353-358). Anterogradely labelled fibres could be followed from the implantations in the posterior interposed nucleus to a medial crescent of the entire contralateral red nucleus. Caudal as well as rostral parts of the posterior interposed nucleus project into the same area of the red nucleus. Implantations restricted to the anterior interposed nucleus label a projection to the contralateral magnocellular red nucleus which is topographically organized. The caudal part of the anterior interposed nucleus projects to the dorsomedial portion of the magnocellular red nucleus, the rostral part to its ventrolateral portion. In addition, a mediolateral organization in the anterior interposed nucleus coincides with a caudorostral arrangement in the red nucleus. This topical arrangement corresponds to what has previously been observed in cat and monkey, but due to the small implantation sites used in the present study a more precise mapping of the projection has been obtained. Furthermore, our implantations of WGA-HRP into the red nucleus show especially well the latter topical arrangement in the projection. The observations mentioned above are discussed and related to previous studies of the rubrocerebellar and cerebellorubral projections.     

The fine topography of climbing fiber projections to the paramedian lobule of the cerebellum in the cat

Motor cortex and somatosensory afferents of climbing fibers (CFs) which terminate in the two rostral folia of the paramedian lobule of the cerebellum were studied in pentobarbital-anesthetized cats. CF responses were elicited in all but one Purkinje cell recorded within the paramedian lobule by stimulation of one or more pericruciate sites; 67% of these also had a peripheral receptive field or were excited by stimulation of the superior radial, sciatic, or infraorbital nerve. CFs responded to stimulation of peripheral nerves at either short latency (14 to 34 ms) or long latency (<120 ms), or gave a mixture of both responses. Those responding at long latency generally did not have peripheral receptive fields. The forelimb was predominantly represented in folia a and b, although it was noted that the relationship between bodily representation and surface landmarks was variable between cats. The proximal portion of the limb was represented medially and the distal part laterally. A clear relation was established between the location of the lowest-threshold cortical site and the peripheral afferents which evoked a CF response in any given cell. The cortical site was generally in a region controlling movements of the body parts on which the peripheral receptive field was found. Two populations of CFs exist in this region, one receiving convergent and complementary cortical and peripheral information and another which, under the present experimental conditions, is excited only from the cortex. It is suggested that these two populations may project as interdigitating bands which run across the long axis of the folia.     

Carbon filaments direct the growth of postlesional plastic axons after spinal cord injury

The effect of implantation of carbon filaments and fetal tissues on the axonal regeneration following contusion injury in a rat model was investigated by in situ immunofluorescence. Female Sprague-Dawley rats were subjected to severe contusion injury to the spinal cord at T9-T10. All animals were divided into 5 groups (N = 5/group): normal controls. surgical controls, with carbon filament implants, with fetal tissue implants and with implants consisting of fetal tissue cocultured with carbon filaments. After a 10-week survival period, the astroglial response was assessed by immunoreactive glial fibrillary acidic protein and the neuro-axonal profile by immunoreactive phosphorylated and nonphosphorylated neurofilament proteins. The contusion injury resulted in: (a) dramatically increased immunoreactivity of glial fibrillary acidic protein indicating injury-associated reactive astrogliosis, (b) increase in immunoreactive phosphorylated neurofilament protein indicating upregulated phosphorylation of neurofilament protein, (c) with no change in the highly differentiated nonphosphorylated neurofilament protein which normally occur in the nonregenerating mature neurons. Implantation of fetal tissues alone following contusion injury did not show any appreciable change with regard to the immunoreactivities for the glial and neuronal markers studied, compared to the injury controls. However, the implantation of carbon filaments alone or together with fetal tissues directed the growth of glial fibrillary acidic protein-positive astroglia and phosphoneurofilament-positive neurites along the carbon fibers, with no effect on nonphosphoneurofilament protein. In conclusion, implantation of carbon filaments appears to be critical for facilitating the attachment of astroglia forming a substrate and scaffolding that can further support and direct the growth of postlesional plastic axons across the lesion. In addition, carbon filament prostheses in combination with fetal tissue implants provides an improved combinational approach to promote regrowth of injured neurons following injury.     

Muscle fiber conduction velocity changes with length

While recording activity from individual muscle fibers by single fiber EMG (SFEMG), stimulated either through their axons or directly, the length of the recorded muscle fiber was changed—stretched or made shorter—by manipulating the recording needle or by passive joint movements. This resulted in significant changes of latency corresponding to an increase in propagation velocity on shortening of the muscle fiber and to a slowing of its lengthening. The maximum increase in velocity was estimated to 33% and slowing to about 22%. These lengthdependent changes of muscle fiber propagation velocity are suggested to contribute to the supernormal phase of propagation velocity recovery function and to be responsible for an important part of the myogenic, interdischarge interval-dependent, jitter. © 1993 John Wiley & Soncs, Inc.     

Congenital fiber type disproportion with fatal outcome: a case report

A child with congenital fiber type disproportion without structural changes in muscle fibres is reported. Although this pattern suggests a favorable prognosis, the clinical worsening followed by death at the age of 17 months shows that there is as yet no predictor for a benign course for this myopathy.

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Sommario Viene riportato il caso di una bambina affetta da una disproporzione congenita in assenza di modificazioni strutturali delle fibre muscolari. Tale quadro, in constrasto a quanto riportato in letterature, si è accompagnato ad una prognosi infausta con decesso della bambina a 17 mesi.