Ultrasonography of abdominal muscles: Differential diagnosis of late-onset Pompe disease and myotonic dystrophy type 1

Abstract

IntroductionAxial muscles are involved earlier and to a greater extent in late-onset Pompe disease (LOPD) than in myotonic muscular dystrophy type 1 (DM1). We aimed to evaluate abdominal muscles in LOPD compared in DM1 using muscle ultrasonography.MethodsPatients with LOPD (n = 3), DM1 (n = 10), and age- and gender-matched healthy subjects (n = 34) were enrolled for muscle ultrasonography. Patients with LOPD and DM1 were 20 to 59 years of age with a disease duration ranging between 7 and 30 years. A multifrequency linear transducer was used to evaluate quality and thickness in the abdominal muscles and extremities.ResultsThe quantitative muscle echo score revealed a higher Z score in abdominal muscles in Patients with LOPD (scores were relatively normal for the biceps and flexor digitorum groups). Patients with LOPD had significantly lower abdominal muscle thickness than patients with DM1. Abdominal muscle strength was significantly correlated with the muscle echogenicity, trunk impairment scale, and trunk control test. The extremities' sum score was correlated with the total Medical Research Council score.DiscussionThe increased quantitative muscle score in abdominal muscles, sparing the biceps and flexor digitorum groups, may offer differential diagnosis between LOPD and DM1. Ultrasound can easily access abdominal muscles and investigate muscle echogenicity and thickness. A quantitative approach using muscle echogenicity rather than muscle thickness may provide a greater correlation with trunk muscle function.

Muscle ultrasound in patients with late-onset Pompe disease identified by newborn screening

“…Future studies may include ultrasonographic measurement of EI in the diaphragm, but technical difficulties of imaging such a thin muscle may complicate assessments. Recent work has identified that transversus abdominis is affected in LOPD to a greater extent than the biceps and flexor digitorum [ 25 ]. Future assessment should also examine classically affected muscles in LOPD such as hamstrings, hip adductors, and other abdominal muscles including obliques to assess if they also fit the pattern of involved muscles on ultrasonography.…”