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Kouyoumdjian J.A.,Neuromuscular Investigation Laboratory | Fanani A.C.S.,Neuromuscular Investigation Laboratory | Stalberg E.V.,Uppsala University
Muscle and Nerve | Year: 2011

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. © 2011 Wiley Periodicals, Inc. Source

Kouyoumdjian J.A.,Neuromuscular Investigation Laboratory | Stalberg E.V.,Uppsala University
Muscle and Nerve | Year: 2012

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 μs and 16.05 6 5.96 μs, respectively. The suggested limit for mean MCD is 22 μs and for outliers is 28 μs. © 2011 Wiley Periodicals, Inc. Source

Stalberg E.,Uppsala University | Sanders D.B.,Duke University | Ali S.,University of Birmingham | Cooray G.,Karolinska University Hospital | And 12 more authors.
Muscle and Nerve | Year: 2016

Introduction: The aim of this study was to create reference values for jitter measured with concentric needle electrodes. Methods: Operators worldwide contributed recordings from orbicularis oculi (OO), frontalis (FR), and extensor digitorum (ED) muscles in healthy controls. Criteria for acceptable signal quality were agreed upon in advance. Fifteen or 20 recordings of acceptable quality from each muscle were required for voluntary and electrical stimulation recordings, respectively. Results: Recordings from 59 to 92 subjects were obtained for each muscle and activation type. Outlier limits for mean consecutive difference and individual jitter data for voluntary activation were: OO, 31 and 45 μs; FR, 28 and 38 μs; ED, 30 and 43 μs; and for electrical stimulation they were: OO, 27 and 36 μs; FR, 21 and 28 μs; ED, 24 and 35 μs. Conclusion: Reference jitter values from concentric needle electrode recordings were developed from signals of defined quality while seeking to avoid creating supernormal values. © 2016 Wiley Periodicals, Inc. Source

Kouyoumdjian J.A.,Neuromuscular Investigation Laboratory | Stalberg E.,Uppsala University
Arquivos de Neuro-Psiquiatria | Year: 2013

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 μs (abnormal in 85.7%) and in frontalis 57.3 μs (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. Source

Naves T.G.,Neuromuscular Investigation Laboratory | Kouyoumdjian J.A.,Neuromuscular Investigation Laboratory
Arquivos de Neuro-Psiquiatria | Year: 2010

Objective: To establish nerve conduction parameters for carpal tunnel syndrome (CTS) electrodiagnosis in the elderly. Method: Thirty healthy subjects (65-86 years), 9 male and 21 female, were studied. Routine median and ulnar sensory and motor nerve conduction studies, median mixed palmar latency, comparative latency techniques median to ulnar (sensory, mixed and motor lumbrical-interossei), median to radial (sensory), and combined sensory index (CSI) were performed in both hands. results: The upper limits of normality (97.5%) were: median sensory distal latency 3.80 ms (14 cm); median motor distal latency 4.30 ms (8 cm); median palmar latency 2.45 ms (8 cm); lumbrical-interossei latency difference 0.60 ms (8 cm); comparative median to radial 0.95 ms (10 cm); comparative median to ulnar 0.95 ms (14 cm); comparative palmar median to ulnar 0.50 ms (8 cm); and CSI 2.20 ms. Sensory and mixed latencies were measured at peak. conclusion: Our results establish new nerve conduction parameters for mild CTS electrodiagnosis in the elderly and will be helpful to reduce the number of false positive cases in this age. Source

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