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Objectives: To compare the results of stimulated SFEMG which use data of region of motor points of the extensor digitorum communis (EDC) muscle in Vietnamese. Subjects and methods: 63 subjects were enrolled in the study, in which 32 subjects performed with stimulating SFEMG in EDC muscles with new method and 31 subjects were with the classic method.
Journal of military pharmaco-medicine n08-2017 RESULTS OF STIMULATED SFEMG WHICH USE DATA OF REGION OF MOTOR POINTS OF THE EXTENSOR DIGITORUM COMMUNIS MUSCLE IN VIETNAMESE Le Tu Quoc Tuan*; Nguyen Van Chuong** SUMMARY Objectives: To compare the results of stimulated SFEMG which use data of region of motor points of the extensor digitorum communis (EDC) muscle in Vietnamese Subjects and methods: 63 subjects were enrolled in the study, in which 32 subjects performed with stimulating SFEMG in EDC muscles with new method and 31 subjects were with the classic method Results: For classic method, mean MCD = 32.90 ± 18.45 and 36.94 ± 21.38 for new method, p = 0.426 It showed that the MCD values obtained to diagnose myasthenia gravis (MG) in the usage of new method were more stable than when using classic method On the other hand, the time to finish a stimulating SFEMG in the new method was shorter but in classic method, electric intensity was smaller It needs to have larger data to confirm the efficacy of this new method in improving stimulated SFEMG technique of EDC muscle, which is one of the current challenges in clinical medicine * Keywords: Simulated SFEMG; Myasthenia gravis; Extensor digitorum communis INTRODUCTION Single-fiber EMG is the most sensitive electrophysiological method for the determination of neuromuscular dysfunction especially in mild cases (ocular MG) and provides an extremely sensitive assessment of the function of single neuromuscular junctions in situ However, substitute disposable concentric needle electrode (CNE) for special single fiber needle to record single-fiber potentials, electromyographers get some technical difficulties One of the two methods of performing the technique of single fiber EMG is stimulated SFEMG The principle of this technique is to place a stimulating electrodes (needle electrodes or disc electrodes) so that it is close to the end plate of the motor nerve that innervate the muscles (usually the obicularis oculi and the EDC); then use a recording electrode (CNE needle) to measure jitter (MCD) results from fluctuations in the time it takes for endplate potentials (EPPs) to reach the threshold for muscle AP generation The motor points of the skeletal muscles, anatomists’ and physiologists’ main interest, have recently drawn much attention from researchers in the field of functional electrical stimulation The muscle motor point has been defined as the entry point * Trieu An Hospital ** 103 Military Hospital Corresponding author: Le Quoc Tuan (ltqtuan@gmail.com) Date received: 20/08/2017 Date accepted: 28/09/2017 194 Journal of military pharmaco-medicine n08-2017 of the motor nerve branch into the epimysium of the muscle belly [1] If stimulating electrode is inserted closed to the terminal branch of motor nerve which innervated target muscle (motor points of skeletal muscle), the electricity will be lower and the time to perform the technique will be shorter Because EDC muscle has a large number of MUPs (around 200 MUPs) and CNE with the radius of the receiving signals is large, so it is difficult and interfere in practice That is why, Stålberg E., Sander D.B has recommended not to use EDC muscle regularly in clinical practice [3] Stimulated SFEMG at EDC muscle (axonal stimulation) Figure 1: Principles of technique of stimulated SFEMG A Figure illustrates the principles of technique B Figure illustrates the axonal stimulation SUBJECTS AND METHODS Subjects To compare 63 results of stimulating SFEMG in EDC muscles, of which 31 results were applied classic method (insert stimulating needle - monopolar needle into EDC by palpate) and 32 results used new method (insert stimulating needle monopolar needle - into EDC with estimating an area - near terminal motor points) All results were done at the EMG laboratory at Nguyen Hoang Medical Center from May 31st 2017 to September 28th, 2017 Methods Case series report Patients were examined by neurologists from many hospitals and medical centers in Ho Chi Minh All of them were done 195 Journal of military pharmaco-medicine n08-2017 repetitive nerve stimulation (RNS) before doing SFEMG 31 patients were done stimulating SFEMG with ordinary method before 10th September and 32 patients were done stimulating SFEMG with new method after this time 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 -10 -20 -30 Figure 2: Anatomical basis for injection of stimulating needle into the EDC muscles - In new method we use ruler to determine the area to insert stimulating needle-monopolar needle - into EDC This region is located on the coordinate axis: X-axis: 74 → 84 mm, Y-axis: -7 → mm in the position of about 1/5 - 2/5 proximal of the D-OX axis (figure 2) Then we also use electric stimulation to make EDC move slightly before doing SFEMG sample to confirm negative In the case of monitoring the clinical status, MCD which was used for 30 recordings should be made for stimulation SFEMG studies We also practised SFEMG with both methods (classic and new) for nine patients who agreed after being explained; the interval between classic method and new method was - 60 days The distance between of the two electrodes was approximately 10 - 15 mm The stimulation rate was 10 Hz with a stimulus duration of 0.05 ms All of patients were done stimulated SFEMG in EDC with recording electrode by new smallest CNE (30G, 25 mm, Natus, USA) For each patient, a minimum of 10 - 15 potentials was sampled to calculate MCD in order to confirm positive and 30 potentials were Only patients who performed SFEMG in the EDC muscle during the initial examination and pure ocular muscle weakness were included in the study 196 The study was performed on the Viking EDX system (Natus, 2017) version 22.0 with a recording bandpass of - 10 kHz Stimulation of the radial nerve was performed with the disposable monopolar Journal of military pharmaco-medicine n08-2017 needle cathode (30G, 37 mm, Natus, USA) and the anode is disc electrode placed on the skin near EDC palpation and use electric stimulation to make EDC move slightly before doing SFEMG - In classic method: We insert stimulating needle-monopolar needle into EDC by We use amplitude level technique to measure jitter (MCD) RESULTS Some characteristics of the subjects 62 results of 49 patients were done (21 males and 28 females) Mean age was 40.90 ± 14.65 (ranged 17 - 71 years old) By the t-test, the measurements did not have statistically significant difference in gender (male and female) and position (left side and right side) (p > 0.05), so we add up each of these groups in turn for descriptive statistics Compare the results of two methods of SFEMG Results of stimulating SFEMG is illustrated by a graph (figure 3): Figure 3: Results of stimulating SFEMG (negative results in the left, positive ones in the right) 197 Journal of military pharmaco-medicine n08-2017 Table 1: Jitter analysis in classic and new method Jitter analysis in classic and new method Items Classic method New method (n = 31) (n = 32) Mean MCD (µs), mean ± SD 32.90 ± 18.45 36.94 ± 21.38 Number of jitter 155450 159547 It showed that the MCD values obtained to diagnose MG with new method is more stable than in classic method But in the new method, the time to finish a stimulating SFEMG was shorter and electric intensity was smaller in classic method The number of jitter when using classic method was bigger compared to new method because sample of classic method was bigger than that of new method We got all results SFEMG with new method However, one patient who was performed with classic method had to stop the procedure because this patient complained a pain and the EDC muscle was swollen at the position of injected stimulating needle DISCUSSION According to Stålberg E, Sander D.B, it is difficult to measure jitter with CNE in the ED muscle, particularly with electrical stimulation This may reflect different organization of muscle fiber within the motor unit in larger muscles compared with facial muscles Thus, Stålberg E, Sander D.B not recommend measuring CN jitter in the ED in routine clinical practice But we think that stimulating SFEMG with new method makes it easier and can be done on more patients than in classic method To the best of our knowledge, 198 no previous studies practise stimulating SFEMG based on estimate an area - near terminal motor points - in which inject electrode for stimulated SFEMG in EDC muscle Because the number of patients in our study is small, we think that it needs to have larger data to conclude the efficacy of this new method CONCLUSION The findings of the study have revealed a new approach of stimulating SFEMG in EDC muscle Based on this approach, practitioners hope to improve technique of stimulated SFEMG in EDC muscle, which is one of the current challenges in clinical medicine [3] REFERENCES Safwat E.D, Abdel-Meguid E.M Distribution of terminal nerve entry points to the flexor and extensor groups of forearm muscles - an anatomical study Folia Morphol 2007, Vol 66, No 2, pp.83-93 Sander D.B Single fiber EMG In: Aminoff M., Daroff R.B.(eds) Encyclopedia of the Neurological Sciences Vol 4, 2nd Edition, Academic Press 2014, pp.169-171 Doi:10.1016/B978-0-12-385157-4.00543-1 Stålberg E, Sanders D.B, Ali.S, Cooray G, Leonardis L, Loseth S., Kouyoumdjian O.A Reference values for jitter recorded by concentric needle electrodes in healthy controls: a multicenter study Muscle Nerve 2016, 53, pp.351-362 Stålberg E, Tronjeli, J.V, Sanders D.B In: Single fiber Electromyography 3rd edition Edshagen Publishing House 2010 Yu Zhou Guanl, Li Ying Cui, Ming Sheng Liu, Jing Wen Niu Single fiber electromyography in the extensor digitorum communis for the predictive prognosis of ocular myasthenia Gravis: A retrospective study of 102 cases Chinese Medical Journal 2015, Vol 128, Issue 20 ... terminal motor points - in which inject electrode for stimulated SFEMG in EDC muscle Because the number of patients in our study is small, we think that it needs to have larger data to conclude the. .. of military pharmaco-medicine n08-2017 of the motor nerve branch into the epimysium of the muscle belly [1] If stimulating electrode is inserted closed to the terminal branch of motor nerve which. .. for injection of stimulating needle into the EDC muscles - In new method we use ruler to determine the area to insert stimulating needle-monopolar needle - into EDC This region is located on the