title: Diagnostic accuracy of concentric needle jitter in myasthenia: Prospective study.
abstract: 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.
authors.affiliation: Department of Neurology, Medical School, Universidade de São Paulo, São Paulo, Brazil.|Fleury Medicina e Saúde, São Paulo, Brazil.
authors.forename: Flavia
authors.initials: F
authors.lastname: C N Machado
authors.affiliation: Neuromuscular Investigation Laboratory, Faculdade Medicina São José do Rio Preto, São Paulo, Brazil.
authors.forename: João
authors.initials: J
authors.lastname: A Kouyoumdjian
authors.affiliation: Department of Neurology, Medical School, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Paulo
authors.initials: P
authors.lastname: E Marchiori
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001905:Botulinum Toxins / Q000494:pharmacology; D004558:Electric Stimulation; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D009157:Myasthenia Gravis / Q000175:diagnosis*; D009339:Needles; D009469:Neuromuscular Junction / Q000187:drug effects / Q000503:physiopathology*; D009498:Neurotoxins / Q000494:pharmacology; D011446:Prospective Studies; D012372:ROC Curve; D055815:Young Adult
chemical_list: D009498:Neurotoxins; D001905:Botulinum Toxins
keywords: ROC curve; SFEMG; concentric needle electrode; jitter; myasthenia gravis; voluntary contraction