甲状腺机能亢进伴发重症肌无力患者电生理研究

目的：探讨甲状腺机能亢进（甲亢）伴发重症肌无力（MG）患者的电生理检测特点，和与慢性甲状腺机能亢进性肌病（CTM）的关系。方法：对7例甲亢伴发MG患者进行神经传导速度（NCV）、重复电刺激（RNS）、针极肌电图（EMG）和单纤维肌电图（SFEMG）检测。结果：7例NCV均正常，RNS5例异常。EMG2例发现有肌病的表现，SFEMG均出现jitter增宽。结论：甲亢病人可伴发MG，还可能同时伴发CTM，进行RNS、EMG、SFEMG检测是有必要的。     

重症肌无力的重复神经刺激检查研究

目的：研究重复神经刺激（ＲＮＳ）检查对重症肌无力（ＭＧ）疾病的诊断价值。方法：对４４例ＭＧ患者进行重复神经刺激检查,共检查１３２条神经。结果：ＭＧ患者１３２条神经ＲＮＳ诱发的波幅衰减阳性率６５２％。受检的三组肌肉中三角肌阳性率最高（８４１％）,测量波面积对ＭＧ的诊断价值优于测量波幅,两种测量方法阳性率比较有显著性差异（Ｐ＜００５）。ＲＮＳ阳性的ＭＧ患者１００％的在低频刺激时即可获得阳性结果,波幅衰减最明显的刺激频率为５Ｈｚ。结论：ＲＮＳ检查在ＭＧ疾病诊断中具有重要价值     

A study of diagnostic yield, technical ease and patient discomfort of low rate repetitive nerve stimulation test in patients with myasthenia gravis

AIM: The diagnostic yield of repetitive nerve stimulation (RNS) study in different muscles has been evaluated in myasthenia gravis (MG) but there is paucity of comprehensive study on technical ease and patient comfort. In this study we evaluate diagnostic yield of RNS test, technical ease and patient discomfort in 8 different muscles in patients with MG. METHODS: Consecutive patients with MG diagnosed on the basis of clinical evaluation, neostigmine test and/or acetylcholine receptor antibody (AchRAb) assay were subjected to 3 Hz RNS study in abductor digiti minimi (ADM), flexor carpi ulnaris (FCU), anconeus, deltoid, trapezius, serratus anterior (SA), nasalis and tibialis anterior (TA) at rest and 3 min after 30 s exercise. Decrement exceeding 10% was considered abnormal. Patient's discomfort was assessed on a 0-5 scale and technical difficulty by the number of repetitions needed to complete the test or abandonment of test. RESULTS: Thirty-three patients with MG whose age ranged between 16-81 y were evaluated. At the time of RNS study the predominant weakness was ocular in 3, oculobulbar in 13 and limb in 17 patients. The highest diagnostic yield of RNS test was with deltoid and nasalis (78.8% each), followed by trapezius (65.5%). The highest mean patient discomfort score was with deltoid (2.4), followed by nasalis (1.3). The technical difficulty was maximal in deltoid needing 36.4% repetitions followed by SA (33.3%). In oculobulbar group the best yield was in nasalis (92.3%) followed by deltoid (84.6%), and in limb variety deltoid (82.4%) followed by SA (80%) and trapezius (75%). Combining the diagnostic yield, patient comfort and technical ease; the choice of muscle for RNS should be ADM followed by trapezius for patient with predominant limb weakness, nasalis and trapezius in oculobulbar and nasalis in ocular.     

单纤维肌电图(SFEMG)的研究进展

单纤维肌电图(single fiber electromyogram,SFEMG)研究的主要内容是骨骼肌同一运动单位相邻两条肌纤维在重复兴奋过程中,电位对时间间隔的变异,即颤抖(jitter)。两根肌纤维的放电间在2—20mS之间,而人体骨骼正常jitter值一般为5-55uS,因此在引导、测量、分析方面难度较大。随着科学技术的发展,SFEMG已在生理学科的研究和临床医学诊断等领域中占有重要地位。本文阐述了单纤维肌电图jitter的产生、引导、测量、分析的方法及应用价值。     

Single fiber electromyography in normal subjects: reproducibility, variability, and technical considerations.

We performed 59 single fiber electromyography (SFEMG) examinations on 33 patients with spasmodic torticollis, but no other medical or neurological disorder. 14 patients were studied serially (3 examinations over 12 weeks). There was excessive jitter (greater than 55 microseconds) in 14 of 1180 fiber pairs (1.1%). 7 of the 14 abnormal fiber pairs were found at single sites (1 in 20 sites studied). Abnormal jitter occurred at more than 2 of 20 sites in only two patients, both of whom head increased fiber density and were more than 70 years of age. Of the 14 abnormal fibers, subtle technical problems were discovered in 4: bimodal jitter (1); borderline amplitude of single fiber potential (1); and borderline rise time (2). 6 of the 14 jittering potentials were part of a triplet or quadruplet. 4 fibers with increased jitter occurred in pairs and these were seen only in patients over 70. One patient with quiescent non-tropical sprue was excluded from consideration because of increased mean jitter before injection and confirmed during 2 subsequent studies. Therefore, SFEMG is a valid and reliable technique that must be strictly interpreted according to existing guidelines, with special consideration to studies in older patients. Abnormal jitter is rarely found in normal muscle, however, when found, it usually occurs as part of a triplet or multiplet.     

重复频率电刺激对儿童重症肌无力的诊断价值

目的：研究重复频率电刺激（RNS）在儿童重症肌无力（MG）诊断中的价值。方法：对67例儿童MG患儿分别进行面、腋、尺神经的低频RNS，并对结果进行分析。结果：67例MG患儿中属眼肌型（Ⅰ型，最轻型）50例RNS检测结果阳性率为58％～75％；属于全身型（Ⅱ型）17例RNS检测结果阳性率达100％。结论：MG患儿RNS检测结果与临床病情的严重程度呈正相关。     

单纤维肌电图中多电位对颤抖值的影响

目的：确定单纤维肌电图（SFEMG）中最佳的颤抖（jitter）值数目。方法：选择39例重症肌无力患者进行眼轮匝肌SFEMG检测,重新计算多电位的颤抖值并比较差异性。结果：来自异常终板的多电位可以增大颤抖值,该值在不同的Ossermann分型之间无差异。结论：在SFEMG操作中,应采用一个颤抖值的描记,以防止假阳性的结果。     

Phrenic and intercostal repetitive nerve stimulation: a useful electroneurophysiological method to detect the respiratory status of myasthenia gravis patients

OBJECTIVE: To get a comprehensive recognition about the profile of phrenic repetitive nerve stimulation (PRNS) and intercostal repetitive nerve stimulation (IRNS) in healthy people, to investigate the electrophysiological features about respiratory function of myasthenia gravis (MG) patients, and to detect the predictive value of IRNS and PRNS on the respiratory deterioration of MG patients during the pulse treatment with large dosage of adrenal corticosteroid. SUBJECTS AND METHODS: Bilateral PRNS and IRNS with stimulation frequency of 3 and 5 Hz were tested in 28 healthy people and 113 MG patients; limb and cranial repetitive nerve stimulation (RNS), clinical score and forced vital capacity (FVC) were also recorded from those MG patients. Further more, PRNS and IRNS of 36 MG patients were tested 3 days before the beginning of their adrenal corticosteroid pulse treatment, FVC, clinical score and respiratory changes of the MG patients were simultaneously observed. RESULTS: For healthy people, there were no significant differences in the results of PRNS or IRNS in different age, sex and testing sides. After combining the left result with the right one, the amplitude decrement percentage in PRNS and IRNS was less than 7%. PRNS had more technical difficulty than IRNS. For 113 MG patients, FVC was dependent on the values of PRNS, IRNS and facial RNS. A subclinical respiratory dysfunction was found in patients with type I and II MG. The abnormal rate of PRNS in type IIb MG was similar to that in type III and IV MG, even though a difference in the percentage of amplitude decrement between them was observed. Meanwhile, both the abnormal rate and the percentage of amplitude decrement of IRNS had no difference between type IIb MG and type III and IV MG. The general incidence of abnormal PRNS and abnormal IRNS were higher than those of decreased FVC and clinical dyspnea, and the sensitivity of PRNS in type IIa MG patients was higher than that of IRNS. Among 36 MG patients under the adrenal corticosteroid pulse treatment, 14 showed the newly clinical dyspnea or worsened original one 2 to 13 days after the beginning of the therapy. There were significant difference of the above parameters between the patients with and without respiratory deterioration during the treatment. Logistic regression analysis showed that when the mean value of the bilateral IRNS amplitude decrement was larger than 30%, the odds ratio of the occurrence of the respiratory deterioration was 19.523, for both 3 and 5 Hz stimulation. CONCLUSIONS: It is recommended that PRNS and IRNS will be defined as abnormal when their amplitude reduces more than 15%. PRNS and IRNS are neurophysiological indices reflecting the damage of respiratory muscles in MG, they are helpful in evaluating the clinical condition correctly and making the classification of MG properly. It is necessary to test the PRNS and IRNS in type II MG patients regularly. Although the respiratory damage during the adrenal corticosteroid treatment was correlated with PRNS, IRNS, FVC, MG clinical score and type, only IRNS had predictive value on the respiratory deterioration during the treatment.     

重症肌无力患者视、听、体感诱发电位研究

目的：研究重症肌无力(MG)患者视觉诱发电位(VEP)、脑干听觉诱发电位(BAEP)和体感诱发电位(SEP)的变化及其与中枢神经系统(CNS)损害的关系。方法：对22例临床及重复神经电刺激(RNS)确诊的MG患者行VEP、BAEP检测，其中的18例还进行了SEP检测。结果：22例MG患者中VEP异常15例(68．2％)、BAEP异常8例(36．4％)。SEP检查18例均异常，其中上肢SEP异常8例(44．4％)，下肢SEP异常10例(55．6％)。结论：MG患者的VEP、BAEP、SEP均有不同程度异常，表明MG患者可伴有CNS损害，而VEP、BAEP、SEP可作为早期发现MG患者CNS改变的有效检测手段。     

Facioscapulohumeral muscular dystrophy. A quantitative electromyographic study

BACKGROUND: Quantitative electromyography (EMG) using different needle techniques has not been performed or reported on a relatively large group of patients with facioscapulohumeral muscular dystrophy (FSHD). Purpose: To establish statistically: (1) correlations between clinical features of patients (age, disease duration and degree of weakness) and quantitative needle EMG/SFEMG,; (2) correlations between different EMG parameters in the patient group, and (3) quantitative EMG differences comparing patients with a healthy control group. METHODS: Nerve conduction studies, and needle EMG (motorunit analysis, MacroEMG, SFEMG) were performed on Mm. triceps brachii and Mm. tibialis anterior according to standard techniques on 20 patients with FSHD. RESULTS: Nerve conduction studies were normal. In Mm. triceps brachii and, to a lesser extent, Mm. tibialis anterior motorunit analysis and MacroEMG showed myopathic changes, that correlated with patient clinical parameters. In Mm. triceps brachii (but not in Mm. tibialis anterior) EMG results were statistically different in patients compared to control group data. The most sensitive indicators of a myopathy were MUP duration (motorunit analysis) and MUP area (MacroEMG). In the Mm. triceps brachii SFEMG revealed correlations between worsening pooled MCD data and patient clinical parameters. Pooled MCD results did not correlate with other MUP parameters. SFEMG showed abnormal jitter only in 2 patients with the longest disease duration. CONCLUSION: Quantitative EMG results are compatible with a mild, slowly progressive myopathy. The most sensitive indicators of early muscle disease were MUP duration (motorunit analysis) and MUP area (MacroEMG) that would not be detected on "routine" EMG SFEMG showed subtle, progressive worsening of neuromuscular junction physiology. However, quantitative EMG and SFEMG showed that muscle fiber degeneration and loss followed a course independent of muscle fiber regeneration and reinnervation.     

Jitter analysis utilizing a high speed FM tape recorder

Jitter analysis in single fiber EMG (SFEMG) is usually done on-line during recording. However, this technique frequently prolongs the study and makes re-analysis impossible. We attempted to measure jitter with a high speed FM tape recorder and compare the results with the previously published values. SFEMG data, acquired with voluntary activation on extensor digitorum communis muscle of 25 healthy relatives of children with myasthenia gravis were retrospectively analyzed. Fiber density (FD) was estimated on-line. Five to 18 single fiber action potential (SFAP) pairs were studied in each subject. The wow of the tape recorder was 6 microseconds. Mean (SD) (upper 95th percentile) FD, individual jitter, highest jitter, mean jitter and interspike interval were 1.60 (0.18) (1.90), 25.30 (11.20) (57.00) microseconds, 31.24 (6.87) (47.00) microseconds, 25.08 (5.04) (43.00) microseconds, and 0.67 (0.11) (0.91) ms respectively. Mean jitter in the pooled SFAP pairs and mean MCD were found to be lower than the published values of the Ad Hoc Committee of the AAEM Special Interest Group on Single Fiber EMG. A high speed FM tape recorder can be reliably used for the off-line analysis of jitter.     

Pseudoselectivity of the neuromuscular block in ocular myasthenia: a SFEMG study

The patients with pure ocular myasthenia presenting no signs of neuromuscular transmission defect on classical supramaximal repetitive stimulation were studied using SFMG method. Only those patients were selected to the study in whom the diagnosis of the ocular myasthenia was confirmed by the clinical criteria arranged so as to exclude ophthalmoplegia of the other nature. The series comprises 20 patients in whom the results of the supramaximal repetitive stimulation with the recording from the proximal muscles and with the evaluation of posttetanic phenomena were normal. SFEMG examination was performed in the clinically intact EDC muscle and in 17 patients an elongated jitter, sometimes with blocking was found. Among those three patients with normal results two were in full clinical remission, so there was only one patient presenting the symptoms of ocular myasthenia in whom the neuromuscular transmission defect was absent in the EDC. The results justify an admission that the neuromuscular block in ocular myasthenia is only apparently selective; in fact it concerns all the muscles with a different severity and may be detected if properly sensitive diagnostic methods are applied.     

耻骨直肠肌综合征的常规肌电图与单纤维肌电图比较

本文对１０２例耻骨直肠肌综合征的患者均检查耻骨直肠肌及肛门内、外括约肌共３０６块肌肉，检测６１２０个运动单位。结果表明：常规肌电图（ＥＭＧ）和单纤维肌电图（ＳＦＥＭＧ）在耻骨直肠肌肥厚组和耻骨直肠肌痉挛组异常率分别为９２．２％（５９／６４）、９５．３％（６１／６４）和８６．３％（３３／３８）、６３．２％（２４／３８）。提示ＥＭＧ和ＳＦＥＭＧ对耻骨直肠肌肥厚症和痉挛症具有重要诊断价值。     

肌萎缩侧索硬化低频电刺激时波幅的衰减

目的:为了探讨肌萎缩侧索硬化低频重复电刺激时波幅的变化。方法:运用丹麦丹迪公司生产的Countpoint肌电图机对30例肌萎缩侧索硬化患者及30例正常人进行低频重复电刺激的研究。结果:半数以上的患者波幅呈递减反应,波幅的衰减在有束颤及肌萎缩者明显,动作电位的低波幅与波幅的衰减率是呈相关。结论:肌萎缩侧索硬化存在神经肌肉接头损害。     

Single fiber electromyography (SFEMG) in mitochondrial diseases (MD)

Conventional EMG, nerve conduction studies and SFEMG were performed in 18 patients with various phenotypes of MD. 14 cases showed findings consistent with mild myopathy, 2 patients signs of sensory-motor axonal neuropathy and 2 cases a mixture of myopathy and axonal neuropathy. Motor unit fiber density was mild increased in 8 out of 13 tested cases. Jitter was abnormal in 10 out of 18 tested patients. Jitter abnormalities were not related to myopathic or neurogenic features in the EMG study, and may be observed in muscles without clinical weakness. The results suggest the existence of neuromuscular transmission disturbances in patients with MD.     

重症肌无力患者的神经电生理分析

本文报道了47例重症肌无力患者的神经电生理表现。重复频率刺激(RNS)异常率为53％,其中,腋神经19条,递减14条(73％);面神经23条,递减10条(43％);尺神经33条,递减12条(36％)。23例病人进行了常规肌电图检查,12例运动单位时限缩短(54％)。文中讨论了重复频率刺激,腋神经阳性率最高,而尺神经阳性率最低的原因。     

Myokymic discharges: prompt cessation following nerve root decompression during spine surgery.

In surgical cases during which spine nerve roots are at risk, we have found it useful to monitor EMG from the muscles supplied by those roots. Mechanical irritation of a root results in muscle activity, whose amplified signals can be broadcast over a loudspeaker, providing immediate feedback to the surgeon that the root is being irritated. We report here on a patient undergoing spinal canal decompression and fusion following a burst fracture of the L5 vertebral body sustained five days previously. EMG was continuously monitored from the tibialis anterior (TA) and medial gastrocnemius (MG) muscle groups bilaterally. During the period leading up to decompression, myokymic discharges from the left TA muscle were observed, whereas the other 3 muscles monitored did not show such activity. These semi-rhythmic and repetitive discharges from the left TA ceased immediately following surgical removal of a bone fragment compressing the left L5 nerve root. This indicates that the site of axonal irritation was the nerve root, and that myokymic discharges secondary to acute axonal compression can cease immediately upon nerve root decompression.     

Functional characteristics of the rat jaw muscles: daily muscle activity and fiber type composition

Skeletal muscles have a heterogeneous fiber type composition, which reflects their functional demand. The daily muscle use and the percentage of slow‐type fibers have been shown to be positively correlated in skeletal muscles of larger animals but for smaller animals there is no information. The examination of this relationship in adult rats was the purpose of this study. We hypothesized a positive relationship between the percentage of fatigue‐resistant fibers in each muscle and its total duration of use per day. Fourteen Wistar strain male rats (410–450 g) were used. A radio‐telemetric device was implanted to record muscle activity continuously from the superficial masseter, deep masseter, anterior belly of digastric and anterior temporalis muscles. The degree of daily muscle use was quantified by the total duration of muscle activity per day (duty time) exceeding specified levels of the peak activity (2, 5, 20 and 50%). The fiber type composition of the muscles was examined by the myosin heavy chain content of the fibers by means of immunohistochemical staining. At lower activity levels (exceeding 2 and 5% of the peak activity), the duty time of the anterior belly of digastric muscle was significantly (P < 0.01) longer than those of the other muscles. The anterior belly of digastric muscle also contained the highest percentage of slow‐type fibers (type I fiber and hybrid fiber co‐expressing myosin heavy chain I + IIA) (ca. 11%; P < 0.05). By regression analysis for all four muscles, an inter‐muscular comparison showed a positive relationship between the duty time (exceeding 50% of the peak activity) and the percentage of type IIX fibers (P < 0.05), which demonstrate intermediate physiological properties relative to type IIA and IIB fibers. For the jaw muscles of adult male rats, the variations of fiber type composition and muscle use suggest that the muscle containing the largest amounts of slow‐type fibers (the anterior belly of digastric muscle) is mainly involved in low‐amplitude activities and that the amount of type IIX fibers is positively related to the generation of large muscle forces, validating our hypothesis.     

The Postnatal Development of Some Twitch and Fatigue Properties of the Ankle Flexor and Extensor Muscles of the Cat

The isometric responses of the medial gastrocnemius (MG), soleus (SOL) and anterior tibial (TA) muscles to single shocks and different modes of repetitive stimulation were studied in kittens of varying postnatal ages and in adult cats. The postnatal decrease in time-to-peak and half-relaxation time of the twitch contractions was similar for the MG and TA muscles and adult values were attained at around 6–7 weeks of age. The SOL muscle displayed a transient decrease in contraction time during the first postnatal weeks, followed later by a slowing towards adult values. The susceptibility to fatigue during iterative stimulation was smallest in the SOL at all ages studied, and usually largest in TA. It changed only little for the MG and SOL postnatally while increasing markedly for the TA up until 6–7 weeks of age. Tetanic contraction resulted in similar depressions in contractile tension of all three muscles in the youngest kittens, but the SOL displayed a greater ability to recover from this depression than the MG and, in particular, the TA muscles. Tetanus resistance increased postnatally and adult responses were attained at 6–7 weeks of age.     

单纤维肌电图、重频电刺激在运动神经元病中的研究

本文对48例MND患者进行SFEMG研究,对其中43名MND患者进行RNS测定,研究发现:MND患者SFEMG阳性率为73％,在RNS检测中,部分MND患者有类重症肌无力现象的表现,即低频刺激时波幅递减,高频刺激波幅的递增反应。提示MND存在神经肌肉接头功能障碍,且以突触前损害可能性大。