title: Single-fiber electromyography of masseter muscle in myasthenia gravis.
abstract: Jitter after axonal microstimulation in the masseter muscle was studied in 30 consecutive patients (12 women) with myasthenia gravis (MG). Patients' mean age was 42.3 (12-75), median disease duration was 3 months (1-72), and onset was ocular (15 cases), oculobulbar (7), bulbar (6), or generalized (2). There were 23 newly-diagnosed patients. Nine cases developed purely ocular MG and 21 cases developed generalized MG. In the latter group, five subjects had a rapidly progressive course and 16 subjects had stable or well-controlled disease (MGFA grade 2-3). Six patients did not have circulating anti-acetylcholine receptor antibodies. Masseter single-fiber electromyography (SFEMG) was abnormal in 6 of 9 ocular MG patients and in all generalized cases (overall sensitivity 27 of 30 cases or 90%; confidence interval 79.3%-100.0% at P = 0.95). Masseter should be considered for SFEMG in diagnosis of MG, especially in cases with bulbar onset.
authors.affiliation: Department of Neurology, Ibn Sina Hospital, Safat, Kuwait City, Kuwait.
authors.forename: Adnan J
authors.initials: AJ
authors.lastname: Khuraibet
authors.forename: Rossen T
authors.initials: RT
authors.lastname: Rousseff
authors.forename: Raed
authors.initials: R
authors.lastname: Behbehani
authors.forename: Asmahan F K
authors.initials: AF
authors.lastname: al-Shubaili
authors.forename: Riyadh A
authors.initials: RA
authors.lastname: Khan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D004558:Electric Stimulation; D004576:Electromyography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008406:Masseter Muscle / Q000294:innervation* / Q000502:physiology*; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D009157:Myasthenia Gravis / Q000175:diagnosis* / Q000503:physiopathology*; D012680:Sensitivity and Specificity