| 1. |
- Caliandro, Pietro, et al.
(author)
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Jitter of Corticospinal Neurons During Repetitive Transcranial Magnetic Stimulation : Method and Possible Clinical Implications
- 2014
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In: Brain Stimulation. - : Elsevier BV. - 1935-861X .- 1876-4754. ; 7:4, s. 580-586
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Journal article (peer-reviewed)abstract
- Background: Repetitive transcranial magnetic stimulation (rTMS) of the motor cortex activates corticospinal neurons mainly through the depolarization of cortico-cortical axons belonging to interneurons of superficial layers. Objective: We used single-fiber electromyography (SFEMG) to estimate the "central jitter" of activation latency of interneural pools from one pulse of TMS to another. Methods: We evaluated 10 healthy subjects and one patient with multiple sclerosis. By recording SFEMG evoked activity from the left first dorsal interosseous (FDI), we first used a standard repetitive electrical 3 Hz stimulation of the ulnar nerve at the wrist to calculate the mean consecutive difference from at least 10 different potentials. The same procedure was applied during 3 Hz repetitive TMS of the contralateral motor cortex. The corticospinal monosynaptic connection of the FDI and the selectivity of SFEMG recording physiologically justified the subtraction of the "peripheral jitter" from the whole cortico-muscular jitter, obtaining an estimation of the actual "central jitter." Results: All subjects completed the study. The peripheral jitter was 28 mu s +/- 6 and the cortico-muscular jitter was 344 mu s +/- 97. The estimated central jitter was 343 +/- 97 mu s. In the patient the central jitter was 846 mu s, a value more than twice the central jitter in healthy subjects. Conclusion: Current results demonstrate that the evaluation of the central component of the cumulative cortico-muscular latency variability in healthy subjects is feasible with a minimally invasive approach. We present and discuss this methodology and provide a "proof of concept" of its potential clinical applicability in a patient with multiple sclerosis.
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| 2. |
- Chroni, Elisabeth, et al.
(author)
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Usefulness of assessing repeater F-waves in routine studies
- 2012
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In: Muscle and Nerve. - : Wiley. - 0148-639X .- 1097-4598. ; 45:4, s. 477-485
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Journal article (peer-reviewed)abstract
- INTRODUCTION: Repeater F-waves are sometimes seen in routine studies.METHODS: We retrospectively reviewed the clinical significance of repeater F-waves in median, ulnar, and fibular nerve recordings in 50 healthy subjects and groups of 50 patients each with diabetic polyneuropathy, amyotrophic lateral sclerosis, carpal tunnel syndrome, ulnar mononeuropathy, and L5 root lesion. The number of identical F-waves and their repetitions in samples of 20 stimuli were estimated.RESULTS: Repeater F-waves occurred significantly more frequently in all nerves and patient groups than in healthy individuals. Their persistence was negatively correlated with that of non-repeater F-waves.CONCLUSIONS: Based on the presented material and recording condition it appears that repeater F-waves differentiate between health and disease but not between different types of pathology of motor neurons or their axons. Even in routinely recorded samples of 20 traces, the index of repeater all F-waves could be used as a sign of nerve pathology.
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| 3. |
- Higashihara, Mana, et al.
(author)
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Evaluation of spinal and bulbar muscular atrophy by the clustering index method
- 2011
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In: Muscle and Nerve. - : Wiley. - 0148-639X .- 1097-4598. ; 44:4, s. 539-546
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Journal article (peer-reviewed)abstract
- Introduction: A reliable electrophysiological marker for clinical trials is increasingly needed in spinal and bulbar muscular atrophy (SBMA). We previously developed a quantitative analysis method for surface electromyography (SEMG), the clustering index (CI) method. Our purpose was to test the utility of the CI method for evaluating lower motor neuron involvement in SBMA patients. Methods: Subjects included 29 SBMA patients and 27 healthy controls. The recording electrode was placed over the abductor digiti minimi (ADM) muscle with a proximal reference. The Z-score, based on the CI method, was compared with compound muscle action potential (CMAP) amplitude and motor unit number estimation (MUNE), with regard to sensitivity. Results: The Z-scores of the CI method, CMAP amplitude, and MUNE were abnormal in 100%, 72%, and 93% of the patients, respectively. Interrater reliability of the CI method was sufficiently high. Conclusion: The CI method is promising as a non-invasive electrophysiological marker in SBMA.
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| 4. |
- Hokkoku, Keiichi, et al.
(author)
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Electromyographs of the flexor digitorum profundus muscle are useful for the diagnosis of inclusion body myositis
- 2012
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In: Muscle and Nerve. - : Wiley. - 0148-639X .- 1097-4598. ; 46:2, s. 181-186
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Journal article (peer-reviewed)abstract
- Introduction: The frequent observation of high-amplitude and long-duration motor unit potentials (MUPs) in inclusion body myositis (IBM) is problematic, because it may lead to a misdiagnosis of amyotrophic lateral sclerosis (ALS).Objective: To document the diagnostic utility of EMG from the flexor digitorum profundus (FDP) muscle for IBM. Methods: Quantitative analyses of MUP parameters were performed in the FDP and biceps brachii (BB) muscles from 7 biopsy-confirmed IBM patients.Results: In the FDP muscle, all MUP parameters were significantly decreased in IBM patients, which indicated the predominance of low-amplitude and short-duration MUPs in this muscle. In the BB muscle, most parameters were increased, suggesting the frequent contamination of high-amplitude and long-duration MUPs.Conclusions: Low-amplitude MUPs in the FDP muscle indicate the presence of an advanced myopathy in this muscle that was extremely weak for all subjects. Examining the FDP muscle would reduce the chance of misdiagnosing IBM as ALS.
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| 5. |
- Kouyoumdjian, Joao A., et al.
(author)
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Concentric needle jitter in stimulated frontalis in 20 healthy subjects
- 2012
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In: Muscle and Nerve. - : Wiley. - 0148-639X .- 1097-4598. ; 45:2, s. 276-278
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Journal article (peer-reviewed)abstract
- Normative data for jitter parameters using a disposable concentric needle have been presented in a few studies. Jitter, expressed as the mean consecutive difference (MCD), was measured in the frontalis muscle in 20 subjects by percutaneous bar stimulation of the temporal nerve branch. The mean MCD for individual studies (20) and for all potentials (600) were 16.05 +/- 2.73 mu s and 16.05 +/- 5.96 mu s, respectively. The suggested limit for mean MCD is 22 mu s and for outliers is 28 mu s.
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| 6. |
- Kouyoumdjian, Joao Aris, et al.
(author)
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Concentric needle jitter on stimulated frontalis and extensor digitorum in 20 myasthenia gravis patients
- 2011
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In: Muscle and Nerve. - : Wiley. - 0148-639X .- 1097-4598. ; 44:6, s. 912-918
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Journal article (peer-reviewed)abstract
- Introduction: Our objective was to study jitter parameters using a concentric needle electrode (CNE) in the extensor digitorum (ED) and frontalis (FR) muscles. Methods: Twenty myasthenia gravis (MG) patients, mean age 44.5 years, were studied. Percutaneous (FR) and intramuscular needle (ED) stimulation approaches were used. Jitter was expressed as the mean consecutive difference (MCD). The filter settings were from 1000 HZ to 10 kHZ. Results: Abnormal MCD was found in 85% for both ED and FR and in 90% when combining the two muscles. An abnormal percentage of outliers was found in 90% for ED and 85% for FR. The mean MCD did not show a difference for ED and FR, but the percentage of outliers and blocking were higher in FR. Abnormality was found in 93.7% (generalized) and in 75% (ocular) of MG cases. For ED outliers abnormality was greater than the MCD. Conclusion: CNE jitter is reliable for investigation of MG, although borderline findings should be judged with caution.
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| 7. |
- Kouyoumdjian, Joao Aris, et al.
(author)
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Concentric needle jitter on stimulated Orbicularis Oculi in 50 healthy subjects
- 2011
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In: Clinical Neurophysiology. - : Elsevier BV. - 1388-2457 .- 1872-8952. ; 122:3, s. 617-622
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Journal article (peer-reviewed)abstract
- Objectives: The aim of this study was to estimate the jitter parameters in healthy controls in stimulated Orbicularis Oculi (OOc) muscle using concentric needle electrode (CNE). Methods: Fifty healthy subjects, 13 males and 37 females (21-56 years, mean age of 38 +/- 9.2 years) were studied. The zygomatic branch of facial nerve was stimulated with a bar electrode. Jitter was expressed as the mean consecutive difference (MCD). Filter settings 1000 Hz-10 kHz. Results: The mean MCD from individual studies (n = 50, Gaussian distribution) was 21.5 +/- 1.99 mu s (median = 21 mu s), ranging from 17.8 to 26 mu s (upper limit, 97.5%, 25.5 mu s). The mean and median MCD from all potentials (n = 1500, non-Gaussian distribution) were 21.6 and 21 mu s, ranging from 7.1 to 39 mu s (upper limit, 97.5%, 33.4 mu s). Conclusions: Suggested practical limits in the OOc for mean MCD was 26 mu s and for outliers 34 mu s. Significance: Stimulation jitter recordings with CNE could be used in practice but borderline findings should be judged with great caution until larger database obtained with uniform setting available.
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| 8. |
- Kouyoumdjian, Joao A., et al.
(author)
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Concentric needle jitter on voluntary activated frontalis in 20 healthy subjects
- 2013
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In: Muscle and Nerve. - : Wiley. - 0148-639X .- 1097-4598. ; 47:3, s. 440-442
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Journal article (peer-reviewed)abstract
- Introduction: Normative data for jitter parameters using a disposable concentric needle have been described in a few studies. Methods: Jitter, expressed as the mean consecutive difference (MCD), was measured in the frontalis muscle in 20 subjects by voluntary contraction. Results: Mean MCD for individual studies (20, Gaussian), all potentials (400, non-Gaussian), and 18th highest value (20, Gaussian) were 19.9 +/- 2.9 s, 19.9 +/- 6.6 s, and 26.9 +/- 4.4 s, respectively. Conclusion: The suggested upper normal limit for mean MCD is 26 s and for outliers is 36 s.
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| 9. |
- Kouyoumdjian, Joao Aris, et al.
(author)
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Stimulated jitter with concentric needle in 42 myasthenia gravis patients
- 2013
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In: Arquivos de Neuro-Psiquiatria. - 0004-282X .- 1678-4227. ; 71:4, s. 237-243
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Journal article (peer-reviewed)abstract
- Objective: To estimate jitter parameters in myasthenia gravis in stimulated frontalis and extensor digitorum muscles using the concentric needle electrode. Methods: Forty-two confirmed myasthenia gravis patients, being 22 males (aged 45.6 +/- 17.2 years-old) were studied. Jitter was expressed as the mean consecutive difference (MCD). Results: MCD in extensor digitorum was 61.6 mu s (abnormal in 85.7%) and in frontalis 57.3 mu s (abnormal in 88.1%). Outliers represented 90.5% for extensor digitorum and 88.1% for frontalis. At least one jitter parameter was abnormal in 90.5% of the combined studies. Acetylcholine receptor antibody was abnormal in 85.7% of the cases. Conclusions: Stimulated jitter recordings measured from muscles using concentric needle electrode can be used for myasthenia gravis diagnosis with high sensitivity. Extensive normative studies are still lacking and, therefore, borderline findings should be judged with great caution.
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| 10. |
- Loseth, Sissel, et al.
(author)
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Polyneuropathy in type 1 and type 2 diabetes : comparison of nerve conduction studies, thermal perception thresholds and intraepidermal nerve fibre densities
- 2010
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In: Diabetes/Metabolism Research Reviews. - : Wiley. - 1520-7552 .- 1520-7560. ; 26:2, s. 100-106
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Journal article (peer-reviewed)abstract
- Background To evaluate possible differences in distal polyneuropathy (PN) characteristics and degree of abnormalities for various small and large fibre parameters in diabetes type 1 (DM1) and type 2 (DM2). Methods Sixty-six DM1 and 57 DM2 patients with or without PN symptoms were included. Nerve conduction studies (NCS), quantitative sensory testing (QST) and quantification of intraepidermal nerve fibres (IENFs) were performed. Z-scores were calculated from reference materials. Results In both groups, 42% had abnormal NCS classification, 42% (DM1) and 39% (DM2) abnormal QST, as well as 40% (DM1) and 32% (DM2) abnormal IENF density. Seventy percent (DM1) and 65% (DM2) had one of the three tests abnormal (differences not significant). Correlations were found between most Z-score parameters and disease duration and HbAlc in DM1, but fewer in DM2. In multivariate analysis, some NCS and QST Z-scores were more abnormal in DM2. Symptom scoring correlated better with NCS and QST parameters in DM1. Conclusions The differences could be referred to disease duration, glycaemic control and possibly patient age. The various parameters from NCS, QST and IENF analysis contribute differently in the assessment of polyneuropathy. Copyright (C) 2009 John Wiley & Sons, Ltd.
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