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.     

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。     

Motor unit remodelling in Duchenne muscular dystrophy. Electrophysiological assessment.

Conventional EMG, motor and sensory conduction velocities, averaging analysis of MUPs, SFEMG, and muscle fiber conduction velocity in situ were performed in 14 boys with Duchenne muscular dystrophy (DD) aged 5 to 11 years. MUPs parameters study showed a striking increment of long duration MUPs followed by satellites and increase of polyphasic potentials of variable duration. The main findings in SFEMG examination were increment in fiber density of the motor unit, large MISI and presence of complex potentials of long duration in all patients. Muscle fiber conduction velocity in situ was significantly slower than in controls, with significant decrease in minimum conduction and increased variability (large SD) in propagation velocity values. Low conduction velocity of muscle fibers, long duration of polyphasics and MUPs followed by satellites, and large MISI were significantly related. These findings support the hypotheses which have suggested that the motor unit remodelling in DD is mainly myogenic. The abnormalities in muscle fiber conduction velocity in situ reflect an increased diameter variation of muscle fibers consistent with splitting fibers, small groups of regenerating and necrotic fibers, and fiber diameter variation found in histological studies. Thus, increased variability in fiber diameter may be the cause of complex and long duration MUPs in DD.     

Needle electromyography in carpal tunnel syndrome

The role of needle electromyography (EMG) in the routine evaluation of carpal tunnel syndrome (CTS) is not clear. The aim of this study was to determine if needle EMG examination of the thenar muscles could provide useful information in addition to the nerve conduction (NC) studies. Electrophysiologic procedures performed on 84 patients (103 hands) consistent with CTS were reviewed. The median thenar motor NC data were matched with the needle EMG findings in the abductor pollicis brevis (APB) muscle. The severity of the needle EMG findings in the APB muscle correlated well with the severity of the motor NC data. As the thenar compound muscle action potential amplitude decreased and the degree of nerve conduction slowing and block across the wrist increased, there was a corresponding increase in the number of enlarged motor units and decrease in the recruitment pattern in the needle EMG findings. Needle EMG examination confined to the thenar muscles in CTS does not seem to provide any further information when the NC data had already established this diagnosis, and it should not be performed routinely.     

Anterior tarsal tunnel syndrome

Three hundred twenty patients complaining of pain and/or numbness of their feet were evaluated in our Clinical Neurophysiology Laboratory. Nerve conduction studies of deep peroneal, superficial peroneal, sural and posterior tibial nerves were studied bilaterally. Needle electromyography (EMG) of anterior tibial, long peroneal, abductor hallucis longus, extensor hallucis longus, gastrocnemius and extensor digitorum brevis muscles were examined bilaterally. Nerve conduction studies of 25 healthy volunteer subjects (16 female, 9 male, age range 36-70, mean age 52.82 +/- 8.8) with no complaint composed the control group. Fourteen of these patients (8 female, 6 male, age range 40-70, mean age 55.73 +/- 12.04) were found to have anterior tarsal tunnel syndrome (anterior TTS) bilaterally or unilaterally. In the patients with anterior TTS, the nerve conduction studies revealed deep peroneal nerve distal latency as 6.5 +/- 1.9 msec; the amplitude as 1.8 +/- 1.3 mV at the ankle level; and the conduction velocity as 41.5 +/- 5.9 m/sec in the distal segment. When these values were compared with the control group statistically, results were found highly significant (p < 0.005). Needle EMG findings in the anterior TTS group showed only in the extensor digitorum brevis muscle. Other nerves and muscles were normal. All patients with anterior TTS were performing Namaz for years, and none of them had the predisposing factor which may cause entrapment neuropathy. So, we suggest that chronic prolonged stretching of the deep peroneal nerve on the dorsum of the foot during Namaz may cause anterior TTS.     

Fiber density in congenital muscle fiber type disproportion. I. Congenital myopathies

In 15 cases with congenital muscle fiber type disproportion, concentric needle EMG (CNEMG) and single fiber EMG (SFEMG) with fiber density (FD) estimation was performed. The aim of the work was to establish the nature of congenital muscle fiber type disproportion. In 11 cases CNEMG revealed interference pattern on maximal effort and low, polyphasic motor unit action potentials (MUAPs) of short duration indicating a myopathic lesion. In four other cases electromyographic changes were less evident. The FD values were slightly increased in 9 cases. This finding could be explained by pronounced muscle fiber splitting with subsequent ephaptic transmission or even secondary denervation and reinnervation. The most important conclusion from our pilot study is the confirmation of the fact that reinnervation with excessive sprouting is not the only mechanism responsible for muscle fiber type disproportion.     

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。     

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.     

长期服用苯妥英钠的癫癎患者神经电生理观察

目的:观察长期服用苯妥英钠的癫患者周围神经损害。方法:应用丹迪Neuromatic2000M型肌电仪,对37例患者进行正中神经和胫后神经的神经传导(NCV),F波和H反射的检测,同时观察肌肉的针极肌电图(EMG)。结果:癫组与对照组比较正中神经感觉速度(P<0·05),波幅(P<0·05),dML(P<0·05),F波出现率(P<0·01),胫后神经感觉波幅(P<0·05),dML(P<0·01),F波潜伏时(P<0·01)。EMG检测未发现损害。结论:长期服用苯妥英钠的癫患者可发生周围神经损害,表现为(1)感觉运动神经均有损害;(2)脱髓鞘及轴索损害都会发生,轴突损害符合远端轴突病;(3)神经损害远近端都有发生;(4)上下肢神经轴突均有损害,以下肢的轴突损害为重。     

长期服用苯妥英钠的癫痫患者神经电生理观察

目的：观察长期服用苯妥英钠的癫痫患者周围神经损害。方法：应用丹迪Neuromatic 2000M型肌电仪，对37例患者进行正中神经和胫后神经的神经传导（NCV），F波和H反射的检测，同时观察肌肉的针极肌电图（EMG）。结果：癫痫组与对照组比较正中神经感觉速度（P〈0．05），波幅（P〈0．05），dML（P〈0．05），F波出现率（P〈0．01），胫后神经感觉波幅（P〈0．05），dML（P〈0．01），F波潜伏时（P〈0．01）。EMG检测未发现损害。结论：长期服用苯妥英钠的癫痫患者可发生周围神经损害，表现为（1）感觉运动神经均有损害；（2）脱髓鞘及轴索损害都会发生，轴突损害符合远端轴突病；（3）神经损害远近端都有发生；（4）上下肢神经轴突均有损害，以下肢的轴突损害为重。     

Disintegration of the motor unit in post-polio syndrome. Part II. Electrophysiological findings in patients with post-polio syndrome

The aim of the study is to investigate the motor unit abnormalities in late postpolio muscular atrophy (PPMA) as compared to those found in patients who had polio 20-30 years prior to examination without any new clinical signs. The quantitative concentric needle EMG and a single fiber EMG techniques were employed. Spontaneous activity, the parameters of individual motor units potentials (MUP), number of complex potentials and their stability, jitter and blocking as well as fiber density (FD) have been evaluated. In PPMA patients (5 subjects) we found in newly weakened muscles: spontaneous activity, high percentage of complex potentials, increased jitter, increased FD. The EMG findings in muscles previously affected but without any signs of progression have been similar. In the patients with stable nonprogressing postpolio muscle atrophy (12) all MUP-s parameters indicated changes similar to PPMA but less marked in initially affected muscle with complete or incomplete recovery as well as sometimes in initially clinically unaffected muscles. These findings suggest that the signs of ongoing reinnervation processes persist many years after polio and that PPMA occurring later in life represents disintegration of the previously reinnervated motor units. It is still unclear whether this disintegration depends on decompensation by different factors of fully reinnervated motor units or whether most of the motor units after polio never regained a stable reinnervation.     

神经电生理检查在肌萎缩侧索硬化症中的应用

目的:观察神经电生理检查在肌萎缩侧索硬化症(amyotrophic lateral sclerosis,ALS)中的应用价值。方法:分别对28例临床确诊ALS、6例临床拟诊ALS、4例临床可能ALS患者进行4个区域的共8块肌肉肌电图(EMG)分析,四肢的磁运动诱发电位(MEP),上肢正中神经、尺神经、下肢胫神经F波检查,在双侧腓肠肌记录H波,四肢远端神经传导测定,包括运动传导速度(MCV)、感觉传导速度(SCV)、复合运动神经动作电位(CMAP)、感觉神经动作电位(SNAP)以及运动末梢潜伏期(DML)进行测定并分析,并与健康对照组30例进行比较。结果:临床确诊ALS的神经电生理测定各值异常均高于拟诊ALS和可能ALS(P<0.05),拟诊ALS和可能ALS组比较没有明显统计学差异。ALS组EMG异常率85%,MEP异常率72.4%,神经传导异常主要表现为CMAP降低36.2%,SCV基本正常,F波出波率下降33.3%,F波振幅增高26.3%,H波振幅增高26.3%。结论:EMG对ALS患者下运动神经元损害有定位诊断价值,EMG是ALS诊断的重要依据;MEP对ALS患者上运动神经元损害有诊断价值,但特异性不高;F波、H波对ALS患者上下神经元神经损害定位有补充诊断价值,神经传导测定用于ALS的鉴别诊断。     

神经电生理对臀部肌注致坐骨神经损伤的诊断价值

目的：探讨神经电生理检测对臀部肌注致坐骨神经损伤的诊断意义。方法：对34例患者进行腓总神经、胫神经的神经传导速度（NCV）检测，并对胫骨前肌、腓肠肌、股二头肌长短头、椎旁肌L4-S1进行针极肌电图检测。结果：34例病例中，腓总神经传导速度NCV异常29例（85．3％），胫神经13例（38．2％），腓总神经、胫神经同时异常8例（23．5％）。经统计学处理，与正常对照组比较差异有显著意义（P〈0．01）。肌电图示，有失神经电位改变者：胫前肌为29例（85．3％），股二头肌短头为29例（85．3％），腓肠肌为13例（38．2％），股二头肌长头为13例（38．2％）。结论：神经电生理检测对臀部肌注致坐骨神经损伤的诊断可提供客观依据。     

Four quantitative EMG methods and theirs individual parameter diagnostic value

Quantitative electromyography (EMG) usage in daily clinical medicine can exclude the investigation results influencing by the electromyographer's subjective factor in needle EMG. The aim of our study was to compare the diagnostic efficiency of these quantitative EMG methods which have found some more consistent application in routine neurologic practice. We have investigated 35 healthy subjects and 59 patients with two basic types of neuromuscular disorders (neuropathies and myopathies) by means of four quantitative EMG methods: 1--modified Buchthal's low threshold MUAPs (motor unit action potentials) analysis; 2--interference EMG pattern Dorfman's and McGill's limited decomposition; 3--interference EMG pattern spectral analysis; 4--interference EMG pattern turns-amplitude analysis. In results analysis parameter's 95% confidence intervals were calculated by Campbell and Gardner and the difference between three subject groups (controls, neuropathies, myopathies) was evaluated by special multidimensional statistics (Hotelling T2 test) using simultaneously all tested parameters of four quantitative EMG methods. The modified Buchthal's low threshold MUAPs analysis was the most effective method in discovering neuropathy and myopathy with area as the best discriminating parameter. The diagnostic power in neuropathies may be increased using selected quantitative EMG methods or theirs individual parameters combinations. Several aspects of applyied quantitative EMG methods and aquired data statistical analysis are discussed.     

Fiber density in congenital muscle fiber type disproportion. II. Congenital muscle hypotonia and hip dislocation

Our previous paper presenting electromyographic findings in patients with congenital fiber type disproportion myopathy, confirmed the myogenic character of the disease process. That group of patients was however fairly heterogenous regarding both the clinical features and the morphological changes in muscle fibers (e.g. cases with central cores). In the present study we have examined 13 children with hypotonia and muscle fiber type disproportion operated on in childhood for congenital hip dislocation. In all cases CNEMG and SFEMG with FD estimation was performed in biceps brachii and quadriceps femoris muscles. In all muscles examined either slight EMG changes indicative of myopathy or a normal EMG pattern was found. None of the patients demonstrated an evident increase in FD values. Normal FD and the recruitment pattern proportional to the force of contractures indicate that the normal number of motoneurons is preserved. Accordingly, our present findings confirm the conclusions of our previous paper.     

Brachial plexopathy: a clinical and electrophysiological study

BACKGROUND: A retrospective study to evaluate the clinical and electrophysiological profile of brachial plexus lesions in a tertiary care center of India. METHODS: Thirty eight patients with brachial plexopathy (idiopathic or traumatic) with detailed electrophysiological studies were sampled. This included detailed motor and sensory nerve conduction studies of the conventional median, ulnar and radial nerves of the upper limbs, CMAP from deltoid, biceps and triceps on stimulating the ERB's point, needle EMG in the appropriate muscles and paraspinal muscles. The electrophysiological studies were performed on both sides irrespective of the clinical involvement and were recorded within 1.61 +/- 2.89 months in idiopathic group and 2.11 +/- 2.65 months in traumatic plexopathy group. The severity of involvement was assessed on MRC scale. ADL scale was used to assess the disability at presentation and subsequent follow up. RESULTS: 12 patients (11 male and 01 female) had idiopathic brachial plexopathy and 26 patients (all male) had traumatic brachial plexopathy. In the idiopathic group the lesion was localized to upper trunk in 58.3% of patients and middle trunk (posterior cord) in 41.66% and none had lower trunk or diffuse involvement. 25% had bilateral involvement. Two patients (16.6%) with idiopathic plexitis had recurrence involving the opposite side during the follow up. In the traumatic group the lesion was localized to the upper trunk in 11.53%, middle trunk (posterior cord) in 57.69% and 30.76% of patients had diffuse involvement. All the patients in traumatic plexopathy group had severe disability while in idiopathic group 91.66% had severe disability and 8.33% had moderate disability. Low amplitude CMAP and F wave abnormality were seen in 16.6% of patients in idiopathic group. On needle EMG 83.3% had fasciculation or fibrillations while none had paraspinal EMG abnormality. In traumatic group low to absent CMAP was seen in 69.2% and 76.92% had F wave abnormality. SNAPs were not recordable in 53.8%. On Needle EMG all the patients showed fasciculation or fibrillations and only 6 (23.0%) had paraspinal muscle fibrillations. Root avulsion could be documented in only four of these cases on MR imaging. CONCLUSIONS: Recovery in the traumatic group correlated well with the electrophysiological abnormalities while no such correlation was evident in the idiopathic group.     

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.     

80例多发性肌炎、皮肌炎患者的肌电图研究

目的：探讨肌电图(EMG)、神经传导速度(NCV)的检测对提高多发性肌炎、皮肌炎的诊断价值。方法：分析80例多发性肌炎、皮肌炎患者肌电图检查中自发电活动,MUP时限、波幅及多相波,最大随意收缩时的募集形式,以及NCV检查及肌肉活检资料。结果：80例患者中65例EMG示肌原性损害,同时观察到15例患者出现NCV的轻度减慢(18．6%)、5例(6．3%)患者NCV远端潜伏期延长、21例(26．3%)患者出现复合肌动作电位波幅轻度下降。10例(12．5%)患者EMG、生化检查、肌肉活检正常,仅表现为MUP多相波增多,但追踪观察三个月后,其中6例患者EMG出现肌原性损害。结论：EMG、NCV测定和追踪监测是诊断多发性肌炎和皮肌炎的有价值的电生理检测方法。     

A comparative study of single fiber electromyography and repetitive nerve stimulation in consecutive patients with myasthenia gravis

AIM: To compare the diagnostic yield of single fiber electromyography (SFEMG) and repetitive nerve stimulation (RNS) in consecutive patients with myasthenia gravis (MG). METHODS: Consecutive 33 patients with MG diagnosed on the basis of clinical features, positive neostigmine test and/or acetylcholine receptor antibody assay were categorized into stage 1 (3), 2A (10), 2B (12) and 2C (8 patients). Low rate repetitive nerve stimulation (3Hz) was performed in distal muscles (abductor digiti minimi, anconeus, flexor carpi ulnaris, tibialis anterior) and proximal muscles (deltoid, serratus anterior, trapezius and nasalis). Decrement exceeding 10% was considered abnormal. Single fiber EMG was performed in extensor digitorum communis (EDC), recording 20 potential pairs. The abnormality was defined as mean jitter exceeding 40 micros or 10% of potential pairs having block or jitter exceeding 54 micros. The abnormality in RNS and SFEMG was compared and correlated with severity of MG. RESULTS: RNS study was carried out in 33 and SFEMG in 30 patients. In 2 patients SFEMG was not possible due to lack of cooperation and in one due to severe weakness. The RNS study was normal in 6 (2 in stage 1, 3 in 2A and 1 in 2B) patients and in all of them SFEMG was abnormal. The abnormality in RNS and SFEMG correlated with severity of MG. CONCLUSION: SFEMG is indicated in the patients with MG in whom RNS test is negative.     

Surface compound action potentials recorded from different locations on the anterior tibial muscle

Supramaximal CMAPs to peroneal nerve stimulation at the knee were recorded from 5 locations on the anterior tibial muscle in 24 patients (30 muscles). The active recording locations were: midpoint of the muscle belly, at 4 cm distal and proximal to it, and at 2 cm lateral and medial to it. Reference electrode was at the medial malleolus. CMAP duration, amplitude, and area were measured, and ratios of their corresponding minimum to maximum values were computed. Thirteen patients (15 muscles) had normal nerve conduction and needle EMG studies. Mean ratios of minimum to maximum values were duration = 0.89, amplitude = 0.67, and area = 0.75. Eleven patients (15 muscles) had abnormal studies, and the mean ratios of minimum to maximum values were duration = 0.87, amplitude = 0.66, and area = 0.71. CMAP duration, unlike amplitude and area, appears least likely to be influenced by the recording electrode location, and is a more stable and reproducible measure during nerve conduction studies. The maximum (or minimum) values in the CMAP duration, amplitude, and area frequently do not coincide to one electrode recording location. A majority of the CMAPs recorded from different muscle locations had an initial negative phase, suggesting that the endplate zones of the anterior tibial muscle are dispersed rather than concentrated in a small region.