title: Repetitive nerve stimulation of facial muscles in MuSK antibody-positive myasthenia gravis.
abstract: To better define electrophysiological abnormalities in myasthenia gravis (MG) patients with muscle-specific tyrosine kinase (MuSK) antibodies (Ab), we compared electrophysiological features of 14 MuSK Ab-positive, 73 acetylcholine receptor antibody (AChR Ab)-positive, and 22 MuSK and AChR Ab-negative (seronegative) patients with generalized disease. Repetitive nerve stimulation (RNS) abnormalities were observed in 86% of MuSK Ab-positive and 82% of AChR Ab-positive patients but in only 55% of seronegative patients. RNS decrements in the orbicularis oculi were more common and severe in the MuSK Ab-positive patients than the other two groups. Single-fiber electromyography (SFEMG) of the extensor digitorum communis was abnormal in 90% of MuSK Ab-positive patients. The high frequency of RNS abnormalities in facial muscles in the MuSK Ab-positive population reflects the propensity for facial muscle involvement in this form of MG and emphasizes the importance of including facial muscles in RNS protocols when evaluating these patients.
authors.affiliation: Department of Neurology, University of Alabama at Birmingham, Birmingham, Alabama, USA. shinjoh@uab.edu
authors.forename: Shin J
authors.initials: SJ
authors.lastname: Oh
authors.forename: Yuki
authors.initials: Y
authors.lastname: Hatanaka
authors.forename: Shoji
authors.initials: S
authors.lastname: Hemmi
authors.forename: Angela M
authors.initials: AM
authors.lastname: Young
authors.forename: Mia L
authors.initials: ML
authors.lastname: Scheufele
authors.forename: Sharon P
authors.initials: SP
authors.lastname: Nations
authors.forename: Liang
authors.initials: L
authors.lastname: Lu
authors.forename: Gwen C
authors.initials: GC
authors.lastname: Claussen
authors.forename: Gil I
authors.initials: GI
authors.lastname: Wolfe
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000328:Adult; D000906:Antibodies / Q000032:analysis; D004558:Electric Stimulation; D004594:Electrophysiology; D005152:Facial Muscles / Q000294:innervation* / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000294:innervation / Q000503:physiopathology; D009157:Myasthenia Gravis / Q000235:genetics* / Q000503:physiopathology; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics* / Q000276:immunology / Q000502:physiology; D011950:Receptors, Cholinergic / Q000235:genetics* / Q000276:immunology / Q000502:physiology
chemical_list: D000906:Antibodies; D011950:Receptors, Cholinergic; C095714:MUSK protein, human; D020794:Receptor Protein-Tyrosine Kinases