title: Qualitative and quantitative skeletal muscle ultrasound in late-onset acid maltase deficiency.
abstract: BACKGROUND
  Acid maltase deficiency (AMD, or Pompe disease) is an inherited myopathic disorder of glycogen degradation. Diagnosis is often delayed. Muscle ultrasound could improve diagnosis.
  
  
  METHODS
  We compared skeletal muscle ultrasound images from adults with AMD (n = 10) to other myopathies (n = 81) and, in AMD, compared qualitative (Heckmatt) and quantitative (backscatter) ultrasound measurements with strength and function.
  
  
  RESULTS
  Qualitative ultrasound was abnormal in at least one muscle in all AMD subjects. Ultrasound patterns specific for AMD were: normal triceps brachii despite abnormalities in elbow flexors (89% vs. 17%, P < 0.0001); focal abnormalities affecting deep more than superficial biceps brachii (40% vs. 4%, P = 0.002); and more severe involvement of vastus intermedius than rectus femoris (40 vs. 11%, P = 0.03). In AMD, both qualitative (Heckmatt) and quantitative (backscatter) ultrasound measures increased with decreasing strength and function.
  
  
  CONCLUSIONS
  Muscle ultrasound identifies the presence and specific patterns of AMD pathology, measures disease severity, and can help in the diagnosis of AMD.
authors.affiliation: Department of Neurology, Washington University School of Medicine, 660 South Euclid Avenue, Box 8111, St. Louis, Missouri 63110, USA. zaidmanc@neuro.wustl.edu
authors.forename: Craig M
authors.initials: CM
authors.lastname: Zaidman
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Malkus
authors.forename: Catherine
authors.initials: C
authors.lastname: Siener
authors.forename: Julaine
authors.initials: J
authors.lastname: Florence
authors.forename: Alan
authors.initials: A
authors.lastname: Pestronk
authors.forename: Muhammad
authors.initials: M
authors.lastname: Al-Lozi
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D006009:Glycogen Storage Disease Type II / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging*; D009135:Muscular Diseases / Q000000981:diagnostic imaging; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D014463:Ultrasonography; D055815:Young Adult