Muscular involvement assessed by MRI correlates to motor function measurement values in oculopharyngeal muscular dystrophy

Oculopharyngeal muscular dystrophy (OPMD) is a progressive skeletal muscle dystrophy characterized by ptosis, dysphagia, and upper and lower extremity weakness. We examined eight genetically confirmed OPMD patients to detect a MRI pattern and correlate muscle involvement, with validated clinical evaluation methods. Physical assessment was performed using the Motor Function Measurement (MFM) scale. We imaged the lower extremities on a 1.5 T scanner. Fatty replacement was graded on a 4-point visual scale. We found prominent affection of the adductor and hamstring muscles in the thigh, and soleus and gastrocnemius muscles in the lower leg. The MFM assessment showed relative mild clinical impairment, mostly affecting standing and transfers, while distal motor capacity was hardly affected. We observed a high (negative) correlation between the validated clinical scores and our visual imaging scores suggesting that quantitative and more objective muscle MRI might serve as outcome measure for clinical trials in muscular dystrophies.