The purpose of this study was to investigate the relationship of muscle MRI findings and gait disturbance in myotonic dystrophy type 1 (DM1) patients. Thirteen patients with DM1 were evaluated by manual muscle strength test and muscle MRI of the lower limb. All DM1 patients presenting with foot drop showed high intensity signals in the tibialis anterior muscles on T1-weighted imaging (p < 0.001). The patients presenting with gait disturbance showed high intensity signals in the semimembranosus, vastus intermedius and gastrocnemius medialis muscles, too. Disturbance of the gastrocnemius lateralis muscles was mild in all DM1 patients. The patients without gait disturbance showed no abnormalities, especially in tibialis anterior muscles on muscle MRI. Muscle MRI is useful for the detection of pathological muscles in DM1 patients with gait disturbance.
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