title: Reliability of SFEMG in diagnosing myasthenia gravis: sensitivity and specificity calculated on 100 prospective cases.
abstract: OBJECTIVE
  The study aimed to determine the utility of single-fibre electromyography (SFEMG) in the diagnosis of myasthenia gravis (MG) in subjects with a clinical suspicion of the disease.
  
  
  METHODS
  We performed a prospective, single-blinded study on 100 consecutive patients. SFEMG was not considered a criterion in making the MG diagnosis. For all cases, a different physician than the one performing SFEMG made the diagnosis of MG. All subjects underwent standard SFEMG of a single muscle, the orbicularis oculi.
  
  
  RESULTS
  SFEMG was abnormal in 67 of 100 patients. A final diagnosis of definite MG was made in 54 patients (30 men/24 women). SFEMG was positive in 53 of 54 patients diagnosed with MG. The sensitivity of SFEMG in diagnosing MG was 98% (95% CI: 0.94-1.02), while the specificity was 70% (95% CI: 0.54-0.86), with a positive predictive value of 79% (95% CI: 0.74-0.79) and a negative predictive value of 97% (95% CI: 0.94-0.99).
  
  
  CONCLUSIONS
  In this cohort of patients, normal SFEMG findings were unlikely to occur in patients with MG.
  
  
  CONCLUSIONS
  SFEMG is not a confirmatory test for the diagnosis of MG, but it has a high negative predictive value in identifying patients without MG.
authors.affiliation: Institute of Neurology, Catholic University, Rome, Italy; Don Carlo Gnocchi Onlus Foundation, Milan, Italy. Electronic address: lpadua@rm.unicatt.it.
authors.forename: L
authors.initials: L
authors.lastname: Padua
authors.affiliation: Institute of Neurology, Catholic University, Rome, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Caliandro
authors.affiliation: 1st Division of Neurology, Department of Neuroscience, Seconda Università, Napoli, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Di Iasi
authors.affiliation: Don Carlo Gnocchi Onlus Foundation, Milan, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Pazzaglia
authors.affiliation: Institute of Neurology, Catholic University, Rome, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Ciaraffa
authors.affiliation: Institute of Neurology, Catholic University, Rome, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Evoli
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001767:Blinking / Q000502:physiology; D015331:Cohort Studies; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000175:diagnosis*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D055815:Young Adult
keywords: Myasthenia gravis; Neuromuscular transmission; Single-fibre electromyography