Qualitative and quantitative skeletal muscle ultrasound in late-onset acid maltase deficiency.

INTRODUCTION

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.