Concentric Needle Research Articles

Use of stimulated electromyography in the analysis of the neuromuscular junction in children.

A screening test is required to diagnose disorders of the neuromuscular junction (NMJ) in children. This Review describes the development of stimulation potential analysis with concentric needle electrodes (SPACE). This nomenclature was chosen to distinguish the technique from single-fiber methodology because of the difficulties in identifying single-fiber potentials in most studies, particularly those with the most severe abnormalities of the NMJ. Performed on orbicularis oculi in children with proven or probable disorders of the NMJ, it demonstrated a sensitivity of 84%, specificity of 71%, negative predictive value of 95%, and positive predictive value of 36%. It is well tolerated and within the capability of any clinical neurophysiologist. When combined with a full electrodiagnostic examination, SPACE provides invaluable information about children with NMJ disorders, whose diagnosis often is difficult. Muscle Nerve 56: 841-847, 2017.

Lip reconstruction using a functioning serratus anterior free flap: preliminary study

Reconstructive surgery to the lips requires the replacement of defective tissues with similarly functioning tissues. While non-dynamic free tissue transfers provide adequate lower lip reconstruction, improved benefits may be obtained with innervated free muscle flaps. This study reports the use of innervated serratus anterior muscle free flaps for lip reconstruction in five patients. All patients had squamous cell carcinoma of either the upper or lower lip. After resection of the tumours, the resultant defects comprised two-thirds of the lips. The innervated serratus anterior muscle free flap was transferred to the lip and an end-to-end vascular anastomosis on the facial artery was performed. The marginal mandibular branch of the facial nerve was preferred for nerve coaptation. The inner and outer surfaces of the flaps were grafted with a split-thickness skin graft. Concentric needle electromyography of the orbicularis oris and frontal muscles was performed for all patients in the preoperative, postoperative, and follow-up periods. All patients survived the surgical operation. Three patients achieved perfect oral sphincter function without drooling. Electromyography at 1 year postoperative demonstrated the successful reinnervation of the serratus anterior muscle. This study demonstrates that lip reconstruction using an innervated serratus anterior muscle free flap is a reliable method, providing a functional lower lip.

3-2-12. Size index revisited: Verification by increased number of subjects

Size Index (SI) is a motor unit potential (MUP) parameter in concentric needle EMG, which can sensitively discriminate between control and neurogenic MUPs. We also proposed the revised SI (rSI) using a logarithmic scale for area/amp. In this study, we greatly increased the number of patients, and investigated the utility of SI and rSI for both neurogenic and myogenic MUPs. The biceps brachii (BB) and tibialis anterior (TA) muscles were investigated. The study population was 1619 control MUPs (26 subjects), 340 neurogenic MUPs (10 subjects), and 498 myogenic MUPs (14 subjects) in BB, and 1245 control MUPs (23 subjects), 566 neurogenic MUPs (19 subjects), and 473 myogenic MUPs (13 subjects) in TA. The coefficient for area/amp was variously changed for SI and rSI. As results, the maximum sensitivity of SI for neurogenic MUPs was 84% for BB and 66% for TA. Similar sensitivity was achieved using rSI. That for rSI for myogenic MUPs was 9% for BB and 25% for TA. These were higher than any other conventional parameters. By choosing appropriate coefficients, SI (for neurogenic MUPs) and rSI (for both neurogenic and myogenic MUPs) will enhance the utility of MUP analyses.

3-2-07. Clinical application of the measurement of muscle fiber conduction velocity using direct muscle stimulation for critical illness myopathy (CIM)

Measurement of the muscle fiber conduction velocity (MFCV) using direct muscle stimulation has been considered to be useful for the evaluation of critical illness myopathy (CIM), although there are rather few reports on this issue. Subjects consisted of 2 normal volunteers, 4 patients with myositis, and 1 patient with CIM. Stimulation was given to the muscle using a monopolar needle and the muscle fiber action potentials (MFAPs) was recorded using a concentric needle electrode. MFCV was calculated based on the onset latencies of the MFAPs recorded at different intramuscular locations. As results, MFCV was 4–5 m/s in the CIM patient. It was 4.2 and 4.8 m/s on average in control subjects, and was 3.6–4.3 m/s in patients with myositis. The CIM patient presented with markedly prolonged duration of the compound muscle action potential (CMAP). Normal MFCV in the CIM patient may suggest that the prolonged CMAP duration in CIM may not be due to the slowed MFCV, but to other mechanisms. MFCV measurement is a difficult technique, and its diagnostic role is yet to be documented, including for CIM.

Single-fiber EMG with concentric electrodes in lambert-eaton myasthenia.

We analyzed jitter recordings made with concentric needle electrode (CNE) single-fiber electromyography (SFEMG) in Lambert-Eaton myasthenia (LEM). Fifteen subjects diagnosed with LEM were studied using CNE-SFEMG in the extensor digitorum (ED) and tibialis anterior (TA) muscles. CNE-SFEMG in the ED and TA was also used to evaluate 12 and 10 healthy controls (HCs), respectively. Ten men and 5 women were diagnosed with LEM based on an increase of 100% in compound muscle action potential amplitude during 50 Hz repetitive nerve stimulation. All patients exhibited markedly greater jitter in the ED (88.8 ± 23.2 µs) and TA (92.2 ± 30.2 µs) than HCs (28.3 ± 3.4 µs and 30.9 ± 5.1 µs, respectively). CNE-SFEMG is sensitive for discovering abnormalities in neuromuscular transmission in LEM. Muscle Nerve 56: 253-257, 2017.

Electrophysiological and neuromuscular stability of persons with chronic inflammatory demyelinating polyneuropathy

We assessed motor unit (MU) properties and neuromuscular stability in the tibialis anterior (TA) of chronic inflammatory demyelinating polyneuropathy (CIDP) patients using decomposition-based quantitative electromyography. Dorsiflexion strength was assessed, and surface and concentric needle electromyography were sampled from the TA. Estimates of MU numbers were derived using decomposition-based quantitative electromyography and spike-triggered averaging. Neuromuscular transmission stability was assessed from concentric needle-detected MU potentials. CIDP patients had 43% lower compound muscle action potential amplitude than controls, and despite near-maximum voluntary activation, were 37% weaker. CIDP had 27% fewer functioning MUs in the TA, and had 90% and 44% higher jiggle and jitter values, respectively compared with controls. CIDP had lower strength and compound muscle action potential values, moderately fewer numbers of MUs, and significant neuromuscular instability compared with controls. Thus, in addition to muscle atrophy, voluntary weakness is also due to limitations of peripheral neural transmission consistent with demyelination. Muscle Nerve 56: 413-420, 2017.

Motor unit potentials of the erector spinae muscle by concentric needle electromyography.

IntroductionThe needle electromyography (EMG) serves to supply additional information in patients with suspected neuromuscular disorders. We aimed to provide motor unit potential (MUP) data by concentric needle EMG in the erector spinae (ES) in comparison with biceps brachii (BB) and lateral vastus (LV).MethodsElectromyography MUP data (n) were obtained in ES (517), BB (539), and LV (627) in 32 healthy volunteers (16f).ResultsMotor unit potential data: amplitude (μV) 393 ± 174 (ES), 375 ± 162 (BB), and 577 ± 304 (LV); duration (ms) 10.4 ± 2.4 (ES), 10.1 ± 2.1 (BB), and 11.1 ± 2.3 (LV), area (μV × ms) 585 ± 327 (ES), 538 ± 267 (BB), and 881 ± 492 (LV); phase number 3.23 ± 0.94 (ES), 2.98 ± 0.76 (BB), and 3.19 ± 0.81 (LV); size index 0.60 ± 0.56 (ES), 0.51 ± 0.53 (BB), and 0.96 ± 0.55 (LV). LV displayed higher values (p at least <.001) for MUP amplitude, duration, area, and size index as compared to both, BB and ES.ConclusionConcentric needle EMG investigations in healthy adult human subjects revealed similar MUP parameters in the ES and BB muscles, while in the LV muscle MUP amplitude, duration, area, and size index were significantly larger. Different neuromuscular disorders display a predominant involvement of proximally located muscles such as truncal muscles. The present results given here may facilitate the diagnosis of neuromuscular disorders.

Jitter measurement with concentric needle in 133 patients with myasthenia gravis: a retrospective analysis

Jitter measurement with concentric needle in 133 patients with myasthenia gravis: a retrospective analysis

Neurophysiology of the pelvic floor in clinical practice: a systematic literature review.

Neurophysiological testing of the pelvic floor is recognized as an essential tool to identify pathophysiological mechanisms of pelvic floor disorders, support clinical diagnosis, and aid in therapeutic decisions. Nevertheless, the diagnostic value of these tests in specific neurological diseases of the pelvic floor is not completely clarified. Seeking to fill this gap, the members of the Neurophysiology of the Pelvic Floor Study Group of the Italian Clinical Neurophysiology Society performed a systematic review of the literature to gather available evidence for and against the utility of neurophysiological tests. Our findings confirm the utility of some tests in specific clinical conditions [e.g. concentric needle electromyography, evaluation of sacral reflexes and of pudendal somatosensory evoked potentials (pSEPs) in cauda equina and conus medullaris lesions, and evaluation of pSEPs and perineal sympathetic skin response in spinal cord lesions], and support their use in clinical practice. Other tests, particularly those not currently supported by high-level evidence, when employed in individual patients, should be evaluated in the overall clinical context, or otherwise used for research purposes.

Afterdischarges following M waves in patients with voltage-gated potassium channels antibodies

ObjectiveTo explore the correlation between afterdischarges in motor nerve conduction studies and clinical motor hyperexcitability in patients with voltage-gated potassium channels (VGKC) antibodies. MethodsSix patients with positive serum antibodies to contactin-associated protein-like 2 (CASPR2) or/and leucine-rich glioma-inactivated protein 1 (LGI1) were recruited, including 5 with autoimmune encephalitis, and 1 with cramp-fasciculation syndrome. Electromyography (EMG), nerve conduction studies (NCS) and F waves were performed, and afterdischarges were assessed. One patient was followed up. ResultsFive patients had clinical evidence of peripheral motor nerve hyperexcitability (myokymia or cramp), and four of them had abnormal spontaneous firing in concentric needle electromyography (EMG). Prolonged afterdischarges following normal M waves were present in all six patients, including the two patients who had no EMG evidence of peripheral nerve hyperexcitability (PNH). Afterdischarges disappeared after treatment with intravenous immunoglobulin (IVIG). ConclusionThe afterdischarges in motor nerve conduction study might be a sensitive indicator of peripheral motor nerve hyperexcitability in patients with VGKC antibodies. SignificanceAfterdischarges in motor nerve conduction study might be more sensitive than needle electromyography for detecting peripheral motor nerve hyperexcitability, and could disappear gradually in accordance with clinical improvement and reduction of antibodies.

Diagnostic accuracy of concentric needle jitter in myasthenia: Prospective study.

The aim of this study was to estimate jitter parameters in the orbicularis oculi muscle using a concentric needle electrode (CNE) in patients with myasthenia gravis (MG) and to determine its diagnostic accuracy for jitter analysis (CNEMG-jitter). CNEMG-jitter was performed in 20 healthy subjects and 33 MG patients using the voluntary contraction technique. Receiver operating characteristic (ROC) curves were constructed to determine cut-off points with the best sensitivity/specificity combination for jitter analysis. CNEMG-jitter yielded high positivity rates for ocular MG (92.3%) and generalized MG (100%). The ROC curve cut-off point that provided the highest sensitivity without false positives was 24.7 μs for mean jitter and 33.1 μs for the 18th highest value. Sensitivity was 93.9% for both parameters. Diagnostic accuracy of CNEMG-jitter was > 96%. CNEMG-jitter yielded high sensitivity and specificity rates. Our reference values were lower than previously published values, possibly due to less technical variation between the different recordings. Muscle Nerve 55: 190-194, 2017.

51. Reference data for quantitative motor unit potential and interference pattern analysis in the genioglossus muscle

Needle electromyography (EMG) of the genioglossus muscle is a useful tool in patients with swallowing problems, that are common in many muscle and nerve diseases. Characteristic changes in motor unit potentials (MUPs) can be distinguished with MUP and interference pattern (IP) analysis. The purpose of this study was to establish reference intervals for MUP parameters using template operated multi-MUP analysis and to evaluate the IP features in the genioglossus muscle (GM) of healthy adults. We studied 28 healthy volunteers (11 men, 17 women, mean age 39 ± 12 years) with standard disposable concentric EMG needles (recording area 0.07 mm2) and an EMG system with standard settings (filters: 5 Hz–10 kHz), using an inframandibular approach. For each MUP parameter (amplitude, duration, turns) mean values and outlier limits (5th and 95th percentile) were calculated from the first 20 sampled MUPs. Data from IP plots (turns/amplitude, activity/envelope and activity/NSS) were collected in order to build normal clouds which contain >90% of the data points. MUP parameters obtained from the GM are similar to those published in literature. IP analysis is not available for healthy GM to our knowledge and could be an objective tool to quantitate the degree of abnormality in muscle and nerve diseases.

Developing Normal Turns-Amplitude Clouds for Upper and Lower Limbs.

Turns and amplitude analysis (T&A) is a frequently used method for automatic EMG interference pattern analysis. The T&A normal values have only been developed for a limited number of muscles. Our objective was to obtain normal T&A clouds for upper and lower extremity muscles for which no normal values exist in the literature. The T&A normative data using concentric needle electrodes were obtained from 68 men and 56 women aged 20 to 60 years. Normal upper and lower extremity T&A clouds were obtained and presented in this article. The T&A normal values collected in this study maybe used to detect neurogenic and myopathic abnormalities in men and women at low-to-moderate muscle contractions. The effect of turns-amplitude data obtained at high force level of muscle contraction and its potential to falsely show neurogenic abnormalities are discussed.

EP 18. Normative values for motor unit potentials in the erector trunci muscle determined by concentric needle electromyography

Background Electromyography (EMG) may give important information in addition to clinical findings in various neuromuscular disorders. Beside spontaneous discharges, motor unit potential analysis is routinely used to assess the size of motor units. Normative values for motor unit potentials (MUP) have been reported for e.g. biceps brachii or vastus muscles. Hardly any information is, however, available about motor unit potential (MUP) parameters of paraspinal muscles. Such information might be of special value, since in patients with myopathies or with spinal muscular atrophy (SMA), a proximal pattern of muscular involvement is the rule. Therefore, the aim of the present investigation was to obtain normative values for MUP parameters of the erector trunci (ET) muscle. Methods Thirtytwo healthy volunteers gave informed consent (O 28.9 ± 9.9 years; 16 women) to investigate the left biceps brachii (BB), vastus lateralis (VL) and ET muscles. BB and VL were investigated for comparative purposes. All EMG investigations and MUP analyses were done by conventional technique by MEK. For the BB and VL, subjects rested in the supine position. For recording the ET, patients were positioned on the right side with their hips, trunk and head in a maximally bent position. The needle electrode was inserted between lumbar vertebrae 1 and 2, two fingers lateral to the midline at a depth of 2.5–4.5 cm. MUP were recruited by extending head and legs simultaneously. MUP data comprized: amplitude (peak-to-peak), duration, area, phase number and size-index. Statistics: Kruskall–Wallis test, Mann-Whitney-U test post hoc . Results A total of 1683 MUP from 96 muscles were available. No statistically significant differences were noted for MUP parameters were detected between females and males. Therefore, values were treated together. Statistical analyses revealed significantly higher values in the VL for amplitude (0.56 ± 0.13 mV), duration (11.9 ± 1.0 ms), area (0.86 ± 0.22 μVs) and size-index (0.94 ± 0.24) in relation to BB: amplitude 0.37 ± 0.05 mV, duration 10.2 ± 0.9 ms, area 0.54 ± 0.11 μVs, size-index 0.52 ± 0.24, and ET: amplitude 0.39 ± 0.07 mV; duration 10.6 ± 1.2 ms; area 0.59 ± 0.16 μVs; size-index 0.60 ± 0.25. For these parameters no significant differences were observed between BB and ET. However, phase numbers were significantly smaller in BB (2.96) as compared with VL (3.18) and ET (3.22). Discussion MUP values in BB and VL are well in line with previously reported values. Therefore, the MUP data given for the ET here may be regarded as valid, too. ET MUP display similar values like those of the BB. Significantly higher values have been measured in the VL, with the exception of phase numbers. Amplitude, duration, area and size-index all depend on the amount of muscle fibres of a motor unit in the close vicinity of the needle electrode. Therefore, it can be inferred that ET motor units have similar dimension like those of the BB, while VL motor units appear to be significantly larger. The smaller dimensions of BB motor units relative to those of the VL may be clear from differences in their functions. For ET, which serves simple and mainly static movements of the vertebral column, larger dimensions of the motor units might have been expected than actually found here. Our results on ET MUP parameters are important for routine clinical practice because they facilitate the diagnosis in patients with suspected neuromuscular disorders such as myopathy or SMA.

Chitosan–bacterial nanocellulose nanofibrous structures for potential wound dressing applications

The fabrication of nonwoven mats containing chitosan and bacterial nanocellulose by electrospinning were considered using two different approaches: (1) simultaneous spinning of chitosan and bacterial nanocellulose solutions using two separate syringes towards the same target and (2) coaxial electrospinning, where chitosan and bacterial nanocellulose were simultaneously electrospun through a spinneret composed of two concentric needles to produce core–shell structures. Co-spinning agents were required in both approaches. A direct blend of chitosan and bacterial nanocellulose and subsequent electrospinning was not feasible due to the incompatibility of their respective solvents. The first approach led to the production of mats containing both chitosan and bacterial nanocellulose nanofibers. However, few bacterial nanocellulose fibers were deposited on the collector. Addition of polylactide as a co-spinning agent and an increase in solution temperature (from 22 to 60 °C) during electrospinning was required to improve both fiber formation and collection. On the other hand, coaxial electrospinning showed the best results for the production of nanofibers containing both chitosan and bacterial nanocellulose. Nanofibers with a good yield were obtained by using a chitosan/poly(ethylene oxide) (2.4/0.6 wt/v%) aqueous solution as the inner layer, and a bacterial nanocellulose solution (0.6 wt/v%) as the outer layer. Co-electrospun nanofibers had a diameter of 85 nm in average, and a narrow size distribution. The core/shell nanostructure was validated by transmission electron microscopy whilst energy-dispersive X-ray spectroscopy analysis showed that the nanofibers contained both chitosan and bacterial nanocellulose along their structure. Finally, the mats obtained by the coaxial approach exhibited strong antimicrobial activity with a decrease of 99.9 % of an Escherichia coli population.

Electrophysiological findings in patients with low density lipoprotein receptor related protein 4 positive myasthenia gravis.

The aim was to determine the electrophysiological profile of our cohort of low density lipoprotein receptor related protein 4 (LRP4) positive myasthenia gravis (MG) patients. A repetitive nerve stimulation (RNS) test and jitter analysis using a concentric needle electrode were performed in 17 LRP4 positive MG patients. The results were compared to 31 muscle-specific tyrosine kinase (MuSK) positive and 28 acetylcholine receptor (AChR) positive MG patients. The RNS test was negative in almost all patients belonging to the LRP4/seronegative and LRP4/MuSK groups. It was positive most frequently in the AChR MG patients, especially those without anti-LRP4 antibodies. The presence of anti-LRP4 antibodies was connected to lower decrement values, whilst the independent presence of anti-AChR or anti-MuSK antibodies was connected to higher decrement values. Lowest jitter was recorded in patients with LRP4/seronegative MG. The highest percentage of pathological jitter analysis test results was present in MuSK and AChR MG patients. The isolate presence of anti-LRP4 antibodies did not influence the mean consecutive difference values, whilst mean consecutive difference values were higher in the presence of anti-AChR or anti-MuSK antibodies. Low density lipoprotein receptor related protein 4 positive patients make a distinct MG subgroup with rarely detected pathological electrophysiological test results. The lack of influence of anti-LRP4 antibodies on the different electrophysiological parameters brings into question the pathogenic role of anti-LRP4 antibodies in MG.

Electrical high-frequency stimulation of the human thoracolumbar fascia evokes long-term potentiation-like pain amplification.

Nociceptive long-term potentiation, a use dependent increase in synaptic efficacy in the dorsal horn of the spinal cord is thought to contribute to the development of persistent pain states. So far, no study has analyzed the effects of high-frequency stimulation (HFS) of afferents from deep tissues (muscle and fascia) on pain perception in the back in humans. In 16 healthy volunteers, the multifidus muscle and the overlying thoracolumbar fascia were stimulated with electrical high-frequency pulses (5 × 100 pulses at 100 Hz) through bipolar concentric needle electrodes placed at lumbar level (L3/L4). Electrical pain thresholds were lower (P < 0.001) and pain ratings were higher for fascia compared with muscle stimulation (P < 0.05). For both tissues, pain ratings increased significantly across the five 100 Hz trains (from 15 to 22 numerical rating scale for fascia, from 8 to 12 numerical rating scale for muscle; both P < 0.01). Fascia HFS increased fascia pain ratings 2.17 times compared with the unconditioned control site (P < 0.001), but had no significant effect on pain sensitivity of the muscle. The HFS in muscle had no significant effect on muscle pain, but decreased pain sensitivity of the overlying fascia by 20% (P < 0.05). In additional experiments using the same electrodes and followed over >60 minutes post-HFS, potentiation by fascia HFS was similar to that of skin HFS. These findings show that the spinal input from the fascia can induce long-term changes in pain sensitivity for at least 60 minutes making it a candidate potentially contributing to nonspecific low back pain.

Post Pelvic Radiotherapy Affectation of the Lower Urinary Tract Peripheral Innervation in Men

Introduction: The periurethral electromyography (EMGs) alterations in men who underwent pelvic radiotherapy (RT), either isolated or combined with surgery, have not been frequently described in the literature. Objective: The study aimed to compare the EMG's data in men undergoing RT versus the non-irradiated control group. Material and Methods: The study included 61 consecutive males, who had undergone RT (27 of them had been operated) and 99 control consecutive patients who underwent a retrospective assessment. The EMGs were performed using a concentric electrode needle perineally, localizing the sphincter by visual and auditory signal (electromyograph MMS Solar Active). Results: 14.8% denervation, 62.9% reinnervation, 14.9% denervation + reinnervation and 7.4% EMG normal. The age (p < 0.001) and neurogenic bladder data (p < 0.001) are risk factors. The smaller the prostate size (obtained by rectal examination) post-RT, the more the chance for an abnormal EMG (p < 0.001). The fact of having had received RT (p < 0.001) is the only risk factor. Conclusion: RT produces lesions over the pudendal nerve, showing denervation even in late periods. The surgery did not behave as a risk factor.

Jitter Values on Voluntary Active Periocular Muscles of Healthy Subjects with Conventional (37 mm) Concentric Needle Electrode.

The aim of this study was to re-evaluate jitter values of healthy subjects in whom pairs of single-fiber-like potentials were recorded from voluntary activated periocular muscles using a disposable 37-mm concentric needle electrode (CNE) with 2-kHz low-cut filtering. We reviewed the recordings of 129 subjects (85 women; 44 men; mean age, 43.8±15.3 years). The m. frontalis group included 116 subjects, and the m. orbicularis oculi group included 18 subjects. Jitter values were expressed as the mean consecutive difference (MCD) of 20 different pairs. The mean MCD (n=2680) was 22.5±9.7 μs (range, 5-121 μs), and the upper 95% confidence limit (CL) was 39 μs. The mean of 134 MCD values for each subject was 22.5±3.7 μs (range, 15-33 μs), and the upper 95% CL was 30 μs. The outer limit of the 18th highest MCD values out of 20 recordings for each subject was 31.3±6.5 μs (range, 18-53 μs), with an upper 95% CL of 43.3 μs. Using a conventional 37-mm CNE with 2-kHz low-cut filtering may be a cost effective alternative to a single-fiber electrode in periocular muscles if strict criteria are used for acceptable signals. Jitter values of >44 μs that were calculated from single-fiber-like action potential pairs should alert the physician regarding the possibility of neuromuscular junction disorders and constitute an indication for a further diagnostic investigation.

The diagnosis value of needle electrode electromyography in vaginismus

Summary Objective To investigate the contribution of needle electrode electromyography (EMG) in the diagnosis of vaginismus. Methods The electromyograhic activity of ischio-cavernosus and bulbo-cavernosus muscles was recorded by using a concentric needle EMG on 9 women with vaginismus, then compared to the EMG activity of no vaginismus women. The agreement between the needle electrode EMG and clinical exam was assessed by measuring the Cohen Kappa coefficient. Results The EMG was abnormal in 7 women presenting vaginismus by showing a significant reactivity after stimulating the vaginal introitus. A hyperexcitability was found in 4 cases. The EMG and clinical findings presented a high level of agreement. Conclusion The pelvic floor muscles in vaginismus patients showed an increased EMG activity at rest and on induction of vaginismus. The needle electrode EMG can be useful for the diagnosis of vaginismus.