Quantitative Assessment of Trunk Muscles Involvement in Patients with Myotonic Dystrophy Type 1 Using a Whole Body Muscle Magnetic Resonance Imaging

Abstract

Objective: The aim of this study was to analyze the pattern of trunk muscles involvement through a muscle MRI, in relation to the clinical data of patients diagnosed with myotonic dystrophy type 1 (DM1).

Materials and methods: Patients with DM1 who visited the neurology department were enrolled (n = 19). In all patients, the fatty degeneration of the muscle MRI in the lower cervical, upper thoracic, middle thoracic, and lumbosacral spine extensor muscle group and trunk flexor muscle group was evaluated. Clinical data, including CTG repeats, spinal deformity were analyzed to find the correlations with the fatty degeneration of trunk muscles in the muscle MRI.

Results: All DM1 patients who presented with very mild to severe functional status showed T1-weghted high intensity signals in the upper-thoracic spine extensor muscle group. The sum MRI score of the spine extensor muscle group showed a significant correlation with the 6-min walking test, and Cobb's angle.

Conclusions: DM1 frequently affects the trunk muscles, even in the early stage of disease progression, regardless of disease severity or age of onset. Among the para-vertebral muscles, the selective involvement of spine extensor muscles may explain the cause of spinal deformities, which mirrors the functional status of DM1.

Keywords: Fat infiltration; Magnetic resonance imaging; Myopathies; Scoliosis; Spinal deformity; Trunk muscle.