title: Distribution and severity of weakness among patients with polymyositis, dermatomyositis and juvenile dermatomyositis.
abstract: OBJECTIVE
  To describe the distribution and severity of muscle weakness using manual muscle testing (MMT) in 172 patients with PM, DM and juvenile DM (JDM). The secondary objectives included characterizing individual muscle group weakness and determining associations of weakness with functional status and myositis characteristics in this large cohort of patients with myositis.
  
  
  METHODS
  Strength was assessed for 13 muscle groups using the 10-point MMT and expressed as a total score, subscores based on functional and anatomical regions, and grades for individual muscle groups. Patient characteristics and secondary outcomes, such as clinical course, muscle enzymes, corticosteroid dosage and functional status were evaluated for association with strength using univariate and multivariate analyses.
  
  
  RESULTS
  A gradient of proximal weakness was seen, with PM weakest, DM intermediate and JDM strongest among the three myositis clinical groups (P < or = 0.05). Hip flexors, hip extensors, hip abductors, neck flexors and shoulder abductors were the muscle groups with the greatest weakness among all three clinical groups. Muscle groups were affected symmetrically.
  
  
  CONCLUSIONS
  Axial and proximal muscle impairment was reflected in the five weakest muscles shared by our cohort of myositis patients. However, differences in the pattern of weakness were observed among all three clinical groups. Our findings suggest a greater severity of proximal weakness in PM in comparison with DM.
authors.affiliation: George Washington University, School of Medicine and Health Sciences, Washington, DC, USA.
authors.forename: M O
authors.initials: MO
authors.lastname: Harris-Love
authors.forename: J A
authors.initials: JA
authors.lastname: Shrader
authors.forename: D
authors.initials: D
authors.lastname: Koziol
authors.forename: N
authors.initials: N
authors.lastname: Pahlajani
authors.forename: M
authors.initials: M
authors.lastname: Jain
authors.forename: M
authors.initials: M
authors.lastname: Smith
authors.forename: H L
authors.initials: HL
authors.lastname: Cintas
authors.forename: C L
authors.initials: CL
authors.lastname: McGarvey
authors.forename: L
authors.initials: L
authors.lastname: James-Newton
authors.forename: A
authors.initials: A
authors.lastname: Pokrovnichka
authors.forename: B
authors.initials: B
authors.lastname: Moini
authors.forename: I
authors.initials: I
authors.lastname: Cabalar
authors.forename: D J
authors.initials: DJ
authors.lastname: Lovell
authors.forename: R
authors.initials: R
authors.lastname: Wesley
authors.forename: P H
authors.initials: PH
authors.lastname: Plotz
authors.forename: F W
authors.initials: FW
authors.lastname: Miller
authors.forename: J E
authors.initials: JE
authors.lastname: Hicks
authors.forename: L G
authors.initials: LG
authors.lastname: Rider
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D015415:Biomarkers / Q000097:blood; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D003882:Dermatomyositis / Q000097:blood / Q000503:physiopathology; D005260:Female; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000097:blood; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009220:Myositis / Q000097:blood / Q000503:physiopathology*; D017285:Polymyositis / Q000097:blood / Q000503:physiopathology; D012189:Retrospective Studies; D012720:Severity of Illness Index
chemical_list: D015415:Biomarkers; D007770:L-Lactate Dehydrogenase