[Skeletal muscle MRI of lower limbs in patients with facioscapulohumeral dystrophy]

Objective: To investigate MRI features of lower limbs in patients with facioscapulohumeral dystrophy(FSHD). Methods: The clinical manifestations, myopathological findings and MRI images of 5 FSHD patients were studied retrospectively from June 2016 to December 2017 at Department of Neurology, Henan Provincial People's Hospital, 3 of which had a family history. Analysis of T(1)WI images enabled us to describe muscle fatty infiltration and STIR images to describe muscle edema. Each muscle was scored according to its fatty degeneration (fat replacement score range from 0-4). Results: The 5 patients were all asymmetrically involved. At the thigh level, the hamstrings were more affected than anterior muscles in 4 patients, and anterior muscles were more affected than hamstrings in only 1 patient. The most affected thigh muscles were usually the adductor magnus, semimembranosus, semitendinosus, femoral biceps long head and vastus medialis muscles (average fat replacement score of each muscle was more than 3). The calves were less affected than thighs.The average fat replacement score of the calf muscles was 1.0 for soleus, 0.9 for medial gastrocnemius, 0.8 for tibialis anterior, and 0.4 for lateral gastrocnemius. There was no fatty infiltration in peroneus and tibialis posterior. 4 out of 5 patients had edema in the lower limb muscles. Conclusion: Asymmetric involvement is a definitely helpful clue suggesting FSHD, and edema is a common phenomenon. At the thigh level, no unique imaging pattern can be highlighted in all the FSHD patients, overall, the hamstring, adductor magnus and vastus medialis are usually the most severely affected muscles. The calf muscles are less affected than the thigh muscles or spared. Soleus, medial gastrocnemius, and tibialis anterior are preferentially involved at the calf level.