title: Effect of Gender, Disease Duration and Treatment on Muscle Strength in Myasthenia Gravis.
abstract: BACKGROUND
  The aim of this observational, cross-sectional study was to quantify the potential presence of muscle weakness among patients with generalized myasthenia gravis (gMG). The influence of gender, treatment intensity and disease duration on muscle strength and disease progression was also assessed.
  
  
  METHODS
  Muscle strength was tested in 8 muscle groups by manual muscle testing and by hand-held dynamometry in 107 patients with gMG and 89 healthy age- and gender-matched controls. Disease duration, severity and treatment history were reviewed and compared with muscle strength.
  
  
  RESULTS
  Patients had reduced strength in all tested muscle group compared to control subjects (p<0.05). Women with gMG were stronger than men (decrease in strength 22.6% vs. 32.7% in men, P<0.05). Regional differences in muscle weakness were also evident, with proximal muscles being more affected. Interestingly, muscle strength did not correlate with disease duration and treatment intensity.
  
  
  CONCLUSIONS
  The results of this study show that in patients with gMG; 1) there is significant muscle weakness, 2) muscle weakness is more pronounced in men than women, 3) shoulder abductors, hip flexors, and neck muscles are the most affected muscle groups and 4) disease duration or treatment intensity alone are not predictors of loss of muscle strength in gMG.
authors.affiliation: Neuromuscular Research Unit, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Gülsenay
authors.initials: G
authors.lastname: Citirak
authors.affiliation: Neuromuscular Research Unit, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Sanja
authors.initials: S
authors.lastname: Cejvanovic
authors.affiliation: Department of Neurology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Henning
authors.initials: H
authors.lastname: Andersen
authors.affiliation: Neuromuscular Research Unit, Department of Neurology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
authors.forename: John
authors.initials: J
authors.lastname: Vissing
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000906:Antibodies / Q000097:blood; D002800:Cholinesterase Inhibitors / Q000627:therapeutic use*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D053581:Muscle Strength Dynamometer; D009157:Myasthenia Gravis / Q000188:drug therapy* / Q000503:physiopathology*; D011950:Receptors, Cholinergic / Q000276:immunology; D012720:Severity of Illness Index; D012737:Sex Factors; D055815:Young Adult
chemical_list: D000906:Antibodies; D002800:Cholinesterase Inhibitors; D011950:Receptors, Cholinergic