title: Sensitivity of repetitive facial-nerve stimulation in patients with myasthenia gravis.
abstract: Repetitive stimulation of the facial nerve is commonly performed in cases of suspected myasthenia gravis (MG) because bulbar weakness is often present, but the most sensitive facial muscle is unknown. We compared the sensitivity of repetitive nerve stimulation (RNS) to the frontalis and nasalis muscles in 244 patients with suspected MG. We found no difference in sensitivity of RNS when recording from these muscles in both ocular and generalized MG. In addition, we confirmed the low sensitivity of RNS for ocular (18%) or generalized (47%) MG. The specificity of facial RNS for both muscles was 100% and, in certain circumstances, may obviate the need for further diagnostic testing.
authors.affiliation: Division of Neurology, 1382-13N, Toronto General Hospital, University Health Network, 585 University Avenue, Toronto, Ontario M5G 2N2, Canada.
authors.forename: Lorne H
authors.initials: LH
authors.lastname: Zinman
authors.forename: Paul W
authors.initials: PW
authors.lastname: O'Connor
authors.forename: Keith E
authors.initials: KE
authors.lastname: Dadson
authors.forename: Rita C M
authors.initials: RC
authors.lastname: Leung
authors.forename: Mylan
authors.initials: M
authors.lastname: Ngo
authors.forename: Vera
authors.initials: V
authors.lastname: Bril
mesh_terms: D000368:Aged; D004558:Electric Stimulation / Q000379:methods*; D004576:Electromyography / Q000379:methods; D005154:Facial Nerve / Q000503:physiopathology / Q000528:radiation effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000175:diagnosis* / Q000503:physiopathology; D012680:Sensitivity and Specificity